Five steps for safety in the hottest automotive in

2022-08-11
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Five steps for safety in the automotive industry

in 2008, China produced 9.5 million vehicles, becoming the second largest automotive production country. Unfortunately, the top car manufacturing enterprises are still dominated by foreign brands and foreign technologies, and China still has a long way to go to become an automobile power. I have been working in the field of mechanical safety for more than ten years. I have noticed that Chinese enterprises generally focus on production first and put safety in a secondary position. The reason is not that our enterprises don't care about employees, but that China's machinery safety awareness is relatively backward, the safety standards are aging, and the standard age is too long. In this article, based on my own personal experience of more than ten years and familiar industry norms and standards, I will briefly introduce to you the five steps to realize the safety of the automotive industry, hoping to bring some thinking and help to the majority of users and peers, and looking forward to your joint contribution to the safety field of China's automotive industry, which is undoubtedly a huge business opportunity and your own strength

the first step is to conduct risk assessment

when designing a machine, engineers should first analyze where there is danger and whether some insurance measures are needed. For example, is there a pinch position, and is it necessary to add a cover? Whether there will be new dangers after installing the cover. Then eliminate the risk, and finally verify whether the risk has been reduced to an acceptable level. If the unfortunate risk cannot be reduced to a qualified level, the designer must redefine its functions for the machine, such as reducing its moving speed, canceling or limiting manual operation, etc. In addition, it is also necessary to consider whether the operator has the opportunity to use the machine incorrectly. For example, is it easy to start unexpectedly? Is the operation panel clearly visible? Whether the function key will be misunderstood and so on

the second step is safe design

the safest machine is the one that does not have the risk of converting the salty waste water produced by the polycarbonate plant into reused salt water. Safety design without photoelectric protection is the first step for designers to consider reducing risks, and it is also the most important and effective step. Find out the risks, and then eliminate the dangerous stations through various designs of the machine itself. For example, whether the mechanical design or the station where the operator is standing is far away from the danger point, and how the braking function is realized, etc

prevent dangerous points, such as avoiding sharp shear openings and punching points, limiting its function (speed and weight), and consider ergonomics to reduce the risks caused by factors such as overextension, bending or fatigue operation

statistical data shows that major or fatal accidents are relatively easy to occur during maintenance. We should minimize personnel exposure to hazardous areas. Consider using more automatic feeding and returning devices, set the maintenance or debugging work outside the "working area", use the workpieces with long trouble free life, and clearly mark the operation. For example, the emergency stop switch should be a red switch with a yellow background (EN) In electrical appliances, it is important to provide a stable and reliable power supply for safety related applications. Designers should consider connecting an independent protection system, such as three national standard approved systems tn/tt/it. When the maintenance is finished, the machine should not generate danger after power transmission, and the system should prevent accidental startup

in addition to the electrical appliances that stop working under normal standards, there should also be controls that may stop the machine in an emergency. According to the requirements of en, the machine should be equipped with a control precision ball screw pair transmission that stops working during normal operation. The zero level shutdown level is used to disconnect the main power supply and driving elements, which is necessary. Below level zero, level 1 or level 2 functions shall be provided, which shall be applied to stops related to safety functions. In addition, the stop command should take precedence over the start command (Level 1, 2 and 3 described in en60204 are completely different from the safety level described in en and EN). The emergency stop switch is only used in emergency situations. For example, if someone is clamped by the machine, it is necessary to disconnect the power of the machine to stop the action. The power includes power supply and any power in the form of non electric

source, pneumatic, hydraulic, etc., and the way of pressure release needs to be considered. The emergency stop switch should be accessible, and there should be no other danger when it is used. The color should be red with yellow background. The driving part can be in various forms, including mushroom type, no foot switch, etc

when the emergency stop switch is used, the machine should be in the stop state until a clear reset command is obtained. According to my previous experience in machine safety appraisal, the reset switch is easy to be ignored. For example, workers in the car body workshop usually wear thick gloves, so the reset switch is designed to be relatively large. At the same time, the emergency stop and reset are set on the same console for convenient arrangement. The emergency stop switch needs to be placed at a position within the reach of a worker, so the reset switch was accidentally placed at a position within the reach of a worker. As a result, another worker accidentally activated the reset switch when moving materials, which almost caused an accident. The elimination method is very simple. You only need to change the direction of the reset switch to reduce the chance of collision

the third step is to adopt technical protective measures

if the risk cannot be solved through the second step, technical protective measures must be adopted. There are many kinds of protective devices to realize machine safety, including cover doors, photoelectric protection, two handed buttons, etc. There are also some monitoring devices, including speed and position monitoring, which cooperate to achieve safety protection. Not all protective devices are integrated on the machine. The simplest and effective fixed mechanical guardrail is independent of the machine. As long as it is properly designed, it is very safe

how to eliminate a specific risk? According to the results of the first step of risk assessment, first determine the required safety level, and then calculate whether the safety protection function (device) can reach or exceed this level according to the level a to e defined in eniso13849. To determine whether the safety function has reached the required level, Enio stipulates three conditions. First, is the trauma caused by the accident serious? Article 2 is the duration and frequency of personnel exposure to risks long? Article 3 is there a big chance for personnel to avoid risks

after defining the required safety level requirements, it is necessary to build a safety protection function. A mechanical press has just been installed with a level 4 safety light curtain of an imported brand. Is there data backup: the test data can be saved in any hard disk partition to ensure a certain safety? The answer is No. Because the light curtain is just a sensor, we also need to consider whether the logic control and execution unit can respond correctly when it needs to respond

first is the system structure, single channel or dual channel? The second is whether the reliability is high or not. What is the trouble free life? Third, is there any fault diagnosis and alarm function? Fourth, is there a high probability of system failure caused by common causes? The fifth is whether the operation procedure is safe (including the comprehensive performance of software and hardware)

so is it better to use a safety light curtain or a mechanically fixed guardrail? If considering the cost of purchasing protective devices, mechanical guardrails should be selected, and if considering production efficiency, safety light curtains should be selected. There is no absolute answer, mainly considering factors such as the frequency of personnel entry and labor intensity. Basically, each protection device has corresponding safety standards, such as en for safety light curtain, en for laser scanner, en for safety camera, en1088 for safety door lock switch, en574 for two hand button, etc

how far should the safety light curtain be installed from the dangerous point? How high should it be from the ground? Eniso13855 replaces the old standard and provides a standard for everyone. Why does the light curtain have a safe distance and the fixed mechanical guardrail has no requirement for a safe distance? Because the light curtain does not produce obstacles, when it detects a person, it sends a brake signal, which is processed by the system and then sent to the execution unit. For example, the relay finally disconnects the power supply. The reaction time was replaced by the moving space. I checked that the calibration distance of a punching machine was 300mm, but the distance was shortened by 50mm due to the replacement of larger tools. I think this 50mm can cause people to be washed off 50mm long fingers in the worst case. Therefore, sufficient safety distance must be ensured. The above problems can be solved only by considering sufficient tools when formulating the distance

before there was no safety programming technology in the 1980s, there were only safety relays applied to electric shock, and the wiring was quite troublesome. Through the efforts of industry experts and the upgrading of standards, safety PLC has been widely used today. Generally, it needs to be applied to safety bus in automobile factories. Today, the popular traffic protocol is mainly profa safe, which is mainly Siemens. The DeviceNet safe protocol developed by three industry leaders, Rockwell, Germany and Omron, Japan, has greatly saved the installation cost. Unfortunately, it has caused another problem, that is, the reaction time is too long. We have discussed the importance of safety distance before. I believe no one wants personnel to take three steps to reach the station. Therefore, the industry has also developed a small safety PLC suitable for on-site installation, with IP67 level protection, waterproof and dustproof, which can react in only 7ms, greatly shortening the safety distance

step 4 safety management

eleven years ago, when I was a sales engineer, I sold a safety light curtain to a customer. He firmly replied that our factory was very safe. Every worker must introduce safety training before taking up his post, and there were warning slogans posted in an obvious position in front of the machine tool. But is it really safe? We cannot achieve 100% safety, but the warning slogan can only be applied when there is still residual danger after the first three steps. I agree that operation training and warning slogans are safety management modes that can effectively prevent accidents

the fifth step is the whole rest appraisal

when a new equipment has just been used, I believe the manufacturer has considered safety. But is an old device that has been used for several years still safe? In Germany, it is stipulated that dangerous machines such as mechanical presses must be identified by qualified inspectors after one year of use. This requires a sum of money, but insurance companies will charge relatively low insurance premiums for enterprises with authentication qualifications. Large enterprises attach great importance to their corporate image and hope to become enterprises respected by citizens. Therefore, the whole off appraisal is a necessary measure to achieve safety in production

With professional experience in the design, production and operation of safety equipment, sick has gradually become a leader in the field of industrial safety

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