Máy cán được sử dụng rộng rãi trong ngành công nghiệp cao su. Các tai nạn liên quan đến máy cán chủ yếu là bị cuốn vào trục cán đang quay trong lúc vận hành, sửa chữa, bảo trì. Nguy cơ xảy ra các tai nạn liên quan đến việc sử dụng máy cán được trình bày cụ thể sau đây.

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The problem of mill safety is not a simple one; there are several major issues involved:

·   mill height,

·   the size of the operator,

·   auxiliary equipment,

·   the way the mill is worked,

·   the tack or stickiness of the stock,

·   stopping distance.

Mill height makes a difference as to where the operator works the mill. For mills less than 1.27 m high, where the height of the operator is greater than 1.68 m, there is a tendency to work too high on the mill or too close to the nip. This allows for a very short reaction time for the automatic safety to stop the mill.

The size of the operator also dictates how close the operator needs to get to the mill face to work the mill. Operators come in many different sizes, and often must operate the same mill. The majority of the time on adjustment is made to the mill safety devices.

Auxiliary equipment such as conveyors or loaders can often conflict with safety cables and ropes. Despite codes to the contrary, often the safety rope or cable is moved to allow for the operation of the auxiliary equipment. This can result in the operator working the mill with the safety cable behind the operator’s head.

While the height of the mill and the auxiliary equipment have a part in the way a mill is worked, there are other factors which enter into the picture. If there is no mixing roll below the mixer to distribute the rubber evenly on the mill, the operator will have to physically move the rubber from one side of the mill to the other by hand. The mixing and moving of the rubber exposes the operator to increased risk of strain or sprain injuries in addition to the hazard of the mill nip.

The tack or stickiness of the stock poses an additional hazard. If the rubber sticks to the mill roll and the operator has to pull it off the roll, a body bar becomes a safety hazard. Operators of mills with hot rubber have to wear gloves. Mill operators use knives. Tacky stock can grab a knife, glove or bare hand and pull it toward the running nip of the mill.

Even an automatic safety device will not be effective unless the mill can be stopped before the operator reaches the running nip of the mill. Stopping distances must be checked at least weekly and the brakes tested at the beginning of each shift. Dynamic electrical brakes must be checked on a regular basis. If the zero switch is not adjusted properly, the mill will move back and forth and damage to the mill will result. For some situations, disc brakes are preferred. With electrical brakes a problem can arise if the operator has activated the mill stop button and then tried an emergency mill stop. On some mills the emergency stop will not work after the mill stop button has been activated.

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Trích đăng từ sách Health and Safety in the Rubber Industry, Naesinee Chaiear, Smithers Rapra Press, 2001, trang 11 – 13

(vtp-vlab-caosuviet)