Emergency inspection and judgment methods

As the public is aware, when printing and packaging equipment are in operation and use, due to various reasons, failures sometimes occur. The correct judgment of failures and causes of failures are conducive to timely resolution and troubleshooting; serious analysis of failure mechanisms It helps to take effective measures to control the occurrence of failures.
At the production site, when a failure occurs in the operation of the machinery and equipment, the mechanics should quickly and accurately determine the fault pens and take corresponding measures. They should be judged directly by asking, looking, smelling, listening, and touching. The question is to ask the operator when the fault has occurred, to figure out whether it was a sudden, gradual, or post-repair, as well as a previous treatment. Operators are familiar with the characteristics of their own operating machinery, use the machine to see when the fault occurs, and provide first-hand information on the analysis of faults, so it is helpful to analyze and determine the cause of the fault; see is to observe the parts when the fault occurs. The position and the type of workpieces and the surrounding environment at the time; sniffing is to use the olfactory organs to smell the smell of the scene to judge, for example: the insulation of the motor or the smell of the paint emitted by the motor winding overheating or the burning of the motor winding fault; Distinguish the parts of the transmission machinery that are not used by the party or the place where it is generated; the touch is whether the temperature or vibration of the hand touching the equipment is normal. In this way, judgments can be made quickly by asking, looking, smelling, listening, and touching the captured information.
When the above basic method is used to judge whether the fault location or the cause of the fault can be determined, it is necessary to consider the method of segmentation isolation or the step-by-step inspection. For example, the paper cutter, if the cutter or the paper press brake does not operate normally, if the pressure is not enough, check the oil pressure first, check the Other aspects normally, and check the oil level, the fuel tank or the tubing head joint when the party is not political; check the electromagnetic valve again. Normal, normal contactor and so on. Of course, for the inspection of this system, it is necessary to find out the principle of action and the sequence of actions, and then trace the faults one by one. The reasons for some failures of offset presses during printing are more complex, including equipment, materials, environmental factors, and operator's skill level. In this case, the “step-by-step method” is used to check for troubleshooting, and the effect is better. . For example, in the offset printing product, there is a ghosting failure. The following step-by-step inspections are used to check the cause. Generally, it is possible to find out why: Check whether the quality of the paper satisfies the quality standards, such as whether there are no flounces or curls; check the impression cylinder. Whether the paper grip force is normal, because the force is insufficient or inconsistent, the paper will be displaced in the imprint; whether the liner is suitable, because the liner status will affect the slippage between the rollers; plate, eraser The cloth cylinder produces axial displacement; the overall accuracy of the offset press is poor.
Through the above-mentioned step-by-step inspection, the purpose of identifying and troubleshooting can generally be achieved.
It is worth mentioning that, whether it is on-site production and management personnel, machine repair personnel or machine operators, it is also very important to be familiar with the fault phenomena of commonly used institutions. In printing and packaging machinery, belt drives, gear transmissions, bearings, and other mechanisms are usually set up. It is important to understand these common mechanism fault diagnosis methods to prevent the extension of machine failures and reduce losses.
The following examples illustrate some common institutional failure phenomena for reference.
First, gear transmission: When the gear meshes in the transmission, it will produce squeaky squeaks, and will increase with the increase of the rotation speed. Generally, the meshing clearance is too small; if the transmission produces a sound, and the sound decreases with the increase of the load, It is the gear meshing gap in the transmission that is too large; if the hum sound is intermittent, it is usually a tight half-circle loose half-circle, which is mostly due to the poor manufacturing accuracy of the gear or the bending deformation of one of the shafts. If a percussive sound is generated in the transmission, the center distance between the two axes is generally large or the gear tooth is thin and narrow.
Second, the belt drive: In the same group, the length of the belt or different groove depth, the pulley shaft bending will produce greater vibration, vibration may also be the source of those sophisticated equipment. If it is adjusted too loosely, a strange sound will be generated at the start, and the rotation will be slow, the driving wheel will be heated, the adjustment will be too tight, the buzzing will occur and the belt and the pulley will be heated, thus damaging the belt.
Third, the bearings, rolling bearings tuned too tight: with the shaft or bearing holes with large surplus, shaft and hole processing accuracy and poor lubrication, high-speed will produce screams and heat, smoke, high speed too loose not only noise Large, it will also damage the shaft and gear on the bearing. After a certain period of time, the bearing will wear out, the accuracy will be reduced, and the ball and roller groove will be damaged. Once this failure occurs, it will inevitably have a bad influence on the normal operation of the machine. Therefore, in machinery and equipment, when bearing assembly components fail and affect product quality, we must not neglect the inspection and treatment of bearing quality. (Chen Jinru) (From "China Packaging Newspaper and Print Weekly")