Productive vibration

Productive vibration is the phenomenon in which an object moves back and forth around a center under the action of an external force. In the production process, vibrations generated by machine rotation, impacts, or the movement of vehicles and ships are known as productive vibrations. Vibration sources encountered in production include: (1) pneumatic tools such as rivet guns, rock drills, air hammers, pneumatic drills, tamping machines, etc ； (2) Power tools: electric drills, electric hammers, electric saws, grinding wheels, etc ； (3) Means of transport: cars, trains, airplanes, ships, motorcycles, etc ； (4) Agricultural machinery: tractors, threshers, harvesters, etc. The above are just a representative portion of vibration tools. As machinery becomes faster, larger, and more complex, there will be an increasing number of tasks that involve vibration. The hazards of vibration to the human body and protection measures: Vibration generated by production tools, equipment, etc. in manufacturing is known as occupational vibration. Vibration sources encountered in production include: (1) pneumatic tools such as riveting machines, rock drills, and air hammers ； (2) Power tools such as electric drills, electric saws, forestry chainsaws, grinders, polishers, grinding machines, and road compaction machines ； (3) Transport vehicles such as diesel locomotives, ships, and motorcycles ； (4) Agricultural machinery such as tractors, harvesters, and threshers. Vibration can affect various systems in the human body, and depending on the way it acts on the body, it can be divided into whole-body vibration and local vibration. A common occupational hazard in production is local vibration. Local vibration is also known as hand-transmitted vibration. It exhibits alternating compression and stretching of human tissues, spreading in all directions. The order of conductivity of vibrations in human tissues is: bone, connective tissue, cartilage, muscle, glands, and brain tissue. The effects of vibration on various systems in the human body are as follows: (1) It causes changes in the electroencephalogram ； Changes in conditioned reflex latency ； Sympathetic hyperactivity ； Unstable blood pressure, unstable heart rhythm, etc ； The sensory functions of the skin are reduced, such as touch, temperature sensation, and pain sensation; in particular, vibration sensitivity is the first to become impaired. (2) Vibrations in the range of 40–300 Hz can cause changes in the morphology and tension of surrounding capillaries, resulting in peripheral vascular spasm and abnormal cerebral blood flow patterns ； In terms of the heart, bradycardia, sinus arrhythmia, and atrial, intraventricular, and atrioventricular conduction block may occur. (3) Decreased grip strength. (4) Large-amplitude vibrations below 40Hz can cause changes in bones and joints; X-ray images of the bones may show bone spurs, osteoporosis, deformation of bone joints, and necrosis. (5) Hearing changes caused by vibration are characterized by a decline in hearing in the 125–250 Hz frequency range; however, in the early stages, hearing loss is primarily seen in the high-frequency range, with hearing loss in the low-frequency range appearing later. Vibration and noise have a combined effect. (6) Prolonged use of vibrating tools can cause local vibration disease. Local vibration disease is a disorder primarily characterized by impaired peripheral circulation, and it can also affect the nerves and motor functions of the limbs. The affected area is usually at the extremities of the upper limbs, with the typical manifestation being episodic whitening of the fingers (referred to as white finger). Our country classified local vibration disease as an occupational disease in 1957. The factors affecting vibration are vibration frequency, acceleration, and amplitude. The human body only perceives vibration at frequencies of 1–1000 Hz. Frequency plays an important role in the course of the disease. 30–300 Hz mainly causes spasm of the peripheral blood vessels, leading to white fingers. When the frequency is the same, the greater the acceleration, the greater the hazard. Vibrations with large amplitude and low frequency primarily affect the vestibular organs and can cause displacement of the internal organs. At a constant frequency, the greater the amplitude, the greater the impact on the body. Cold is one of the important external factors contributing to the development of vibration disease; it can cause a reduction in blood flow, alter blood circulation, lead to insufficient blood supply in certain areas, and thus promote the onset of vibration disease. The longer the exposure to vibration, the higher the incidence of vibration disease. Breaks during work are beneficial for preventing vibration disease. A person’s sensitivity to vibration depends on the position of their body. The human body is sensitive to vertical vibrations when in an upright position ； Sensitive to horizontal vibration in the supine position. Some tasks require maintaining a forced position, with the chest, abdomen, or lower limbs even pressed against the vibrating object, which increases the risks associated with vibration. When the hardness of the processed parts is high, the risk to workers also increases; vibrations with high impact forces can easily cause problems in bones and joints. To protect the health of workers, it is necessary to control the hazards associated with vibration. The main approaches to this are as follows: reforming manufacturing processes to eliminate or reduce tasks that involve using hand-held pneumatic tools, and replacing riveting with hydraulic methods, welding, or bonding ； Improve pneumatic tools by adopting effective vibration reduction measures and changing the location of the tool’s exhaust ports ； Automatic and semi-automatic control devices are used to reduce direct contact between the limbs and the vibrating body ； Those using hand-held vibrating tools should wear double-lined fingerless gloves or glove-lined with foam plastic, and take care to stay warm and protected from the cold ； New workers should undergo pre-employment medical examinations; those suffering from vasospasm, peripheral vascular disorders, and neuritis are prohibited from engaging in vibrating tasks ； Workers exposed to vibration should undergo regular medical examinations at intervals of 2 to 3 years ； Patients with vibration disease should receive necessary treatment, and those who experience recurrent episodes should be removed from vibration-related jobs. This post was last edited by lyhh9024 on 2009-3-13 14:05.]