Printing machine repair and maintenance: the safe operation of printing machines and common troubleshooting


Published on:

2019-01-03

Abstract: In the repair and maintenance of printing equipment, we must adhere to the maintenance-oriented, prevention-oriented thinking, from the organizational form and system to take strong measures to protect the implementation of this work. The following are the printing machine repair and maintenance of common sense for the introduction. Printing machine repair and maintenance of printing machine safety operation and common troubleshooting printing machine safety operation 1, only under the permission and appropriate supervision to operate the machine. 2, published before the operation, all security measures and equipment should be ready. 3, if the machine stops for no reason, should avoid restarting. 4, before starting the machine, should check whether someone is making other adjustments.

Printing machine repair and maintenance: the safe operation of printing machines and common troubleshooting

Abstract: In the repair and maintenance of printing equipment, we must adhere to the maintenance-oriented, prevention-oriented thinking, from the organizational form and system to take strong measures to protect the implementation of this work. The following are the printing machine repair, maintenance of common sense for the introduction.

Printing machine repair and maintenance Printing machine safety operation and common troubleshooting

Safe operation of printing machines

1、Only under the permission and proper supervision can operate the machine.

2、Published before operation, all safety measures and equipment should be ready.

3、If the machine stops for no reason, should avoid restarting.

4、Before starting the machine, should check whether someone is making other adjustments.

5、All tools should be put back to the original place, while ringing the bell to notify other work partners.

6、If the noise is too loud, apply ear plugs.

7、You should avoid putting your hand on the part of the machine rotating digital printing, and your body should not be close to the machine.

8, when the machine is on, do not drill into the machine for some adjustment work.

9, do not try to print from the plate or ink rollers on the ink skin or paper dust coated.

10, do not wipe the roller or roller when the machine is running.

11、Do not salvage the paper.

12, the application of the cloth block, it should be folded to avoid being rolled into the machine term, if there is an accident, you should not try to pull back the cloth block.

13, often check whether the plate and rubber cloth is loose.

14, the application of the correct lubrication tools and lubricants for maintenance work.

15, lubrication work should be strictly and consistently.

16, in the maintenance and repair, the total power should be turned off, to ensure that all parts are locked to avoid the risk of sudden fall.

17、Invest in procurement during maintenance, should be placed at the power switch warning board to prevent others from opening the machine.

Maintenance of printing equipment

They can generally be divided into four categories:

① routine maintenance, also known as routine maintenance, that is, the equipment for cleaning, lubrication, tightening easy to loose fasteners, check the integrity of parts and components.

② primary maintenance, regular (such as once a week) on the equipment in general to check: cleaning the wetting system water bucket, water tank, twist and tighten easy to loose parts, internal and external cleaning of the machine, transmission system, lubrication system, pneumatic system and embossing parts.

③Second-level maintenance, mainly the internal cleaning (including water glue, ink glue) and lubrication of the equipment, targeted disassembly and inspection of key parts, adjustment of the machine and equipment (including the level, etc.), and replacement of wearing parts.

④ three-stage maintenance, the main part of the equipment for disassembly inspection and adjustment, including motor cleaning, check the technical status, replacement of lubricants, etc.; replacement of some parts that reach the specified wear limit, such as bearings key pins, electrical, pneumatic components, etc. To the air pump and maintenance to pay attention to the following points:

a) Clean the air pump inlet filter weekly? motor cooling casings and air pump regulator;

b) Oil the bearings every three months;

c) Every year of operation (or 2500 hours) for a major overhaul to check all major wear parts.

The following points should be noted for the maintenance of air compressors:

a) Check the oil level of the compressor daily, which cannot be lower than the safety mark level;

b) Daily discharge of condensate from the gas storage tank;

c) Clean the air inlet filter cartridge weekly;

d) Monthly inspection of drive belt tightness, clean motor and heat sink;

(e) every 3 months to change 1 oil, and thoroughly clean the oil chamber;

(f) every 1 year to check the decline in air pressure (leakage), if the pressure drop of more than 10%, we must promptly check the replacement of damaged compressor seals;

(g) every two years to overhaul, fold open a comprehensive inspection.

Each printing plant must be based on the actual situation of the existing equipment, from the actual production, to develop the best maintenance system and maintenance rules in line with the existing equipment and production requirements.

General knowledge of printing equipment maintenance

Equipment repair and maintenance of equipment, the content is different, the role is different, repair is mainly to find faults, troubleshooting, repair and replacement of damaged or worn, corroded parts, so that the equipment can operate normally. Repair of equipment is divided into electrical parts and mechanical parts.

①General knowledge of electrical part maintenance

In the daily repair work of printing equipment, the electrical part of the larger proportion, with the continuous development of printing technology and equipment, the degree of automation control is increasingly high, the control system is also more complex. Therefore, electrical maintenance personnel are required to have a high level of technical skills and quality, and understand the principles of computer, will operate. For printing maintenance of electrical personnel, in the daily maintenance work to pay attention to the following points:

(a) carefully read the electrical schematic diagram of the equipment and related documents, from the principle of mastering the electrical principle of the equipment, the principle of the control system. Figure out the location of the electrical components, wiring, piping and numbering, direction.

(b) for the machine and equipment failure, carefully analyze the possible parts of the failure, according to the electrical schematic diagram, wiring diagram, etc. to find the components and lines that may lead to failure, diagnosis, one by one to eliminate.

c) In the electrical repair, the first thing should check the power supply voltage? current is normal, the air pump pressure is up to standard, the lubrication system oil pressure is up to standard, etc. If necessary, the load can be disconnected to help determine whether the mechanical overload caused by electrical failure or protection.

(d) the web offset printing machine uses a pc machine for automatic control, which brings a lot of convenience to troubleshoot electrical problems. Generally in the control cabinet there are light-emitting diodes for fault tips, according to tips to find the parts of the fault. In the more advanced equipment, you can first find tips on the console display, or in the control cabinet with a laptop computer and industrial computer "dialogue" to find the fault system, parts, and then one by one to eliminate.

(e) commonly encountered electrical faults can be summarized as: fuse damage, contactor, relay contact damage, loose wiring, poor contact, button, limit switch failure, safety protection system in a position control switch is not reset, tension control system, paper break system in the photoelectric detection part of the failure, solenoid valve leakage, damage, etc..

f) The motor is the source of power in the printing equipment, the following is a brief introduction to the common faults of DC motor and AC motor respectively.

There are two common faults in DC electric operation: mechanical and electrical. Mechanical faults are mainly manifested as bearing heating, motor vibration, armature and stator core touching and abnormal noise. Generally caused by the rotation of the armature, in the inspection, manual rotation of the armature, observe whether the armature and stator touch, to determine whether the vibration is caused by the motor itself or due to poor transmission device. Motor vibration caused by its own dynamic balance is less likely, often occurring is the concentricity of the transmission device is not good and caused by vibration, this phenomenon occurs after the motor bearing damage, and even lead to armature output shaft deformation.

DC motor electrical fault is most common between the brush and commutator spark, normal operation, the brush and commutator spark is light blue, faint and fine, the brush contact surface is smooth and bright, commutator surface will form a layer of reddish-brown oxide layer film. When the motor does not run normally, the size and color of the spark will change. When the fault is slight, the spark is yellowish red and brighter, the surface of the commutator is black and burn marks appear. If the spark is serious, there will be a large number of red and green sparks, and mixed with flash fire, but also accompanied by a rattling sound, such as not timely shutdown inspection, will soon be commutator and brush, brush seat burned. When the brush position deviates from the geometric center line, the armature winding internal open circuit, short circuit may appear serious sparks. In addition, the brush brand, performance does not match, brush pressure is too large, too small, brush grinding is not good, too little contact area, etc., will cause failure.

The mechanical failure of AC three-phase asynchronous motor is basically the same as that of DC motor. Here is a brief introduction to the common electrical failure, one is a single-phase operation failure, that is, the motor three-phase winding in one phase winding disconnection, when the motor torque significantly reduced, the speed becomes slower, the sound is abnormal, a little longer motor will be burned out due to serious heat; Second, the motor is seriously hot, and even issued a paste odor, this failure may be due to the load is too heavy, may also be caused by the power supply voltage is too low, too high.

②General knowledge of mechanical part maintenance

Mechanical failure can generally be divided into two categories of accidental failure and natural failure, accidental failure is mostly caused by improper maintenance or adjustment, violation of operating procedures, etc., should be avoided as far as possible. Natural failure is difficult to avoid, but can be improved through the use and maintenance level, to extend the effective working time of machinery.

There are three main forms of failure of mechanical parts: fracture, deformation and surface failure, the following are introduced to the printing machinery parts wear, deformation, cleaning methods and folding and unloading assembly.

a)Wear and tear of printing machine parts

During the operation of machinery, if the surface of the parts in relative motion changes in size, shape and surface quality, it is called wear. The change in size, shape and surface quality is called wear.

The main causes of wear of parts are friction and molecular gravity. Wear and tear can be divided into abrasive wear, mechanical friction wear and adhesive wear. The reasons affecting the wear of mechanical parts are generally: speed, pressure, lubrication, temperature, material, processing and fit, etc.

b)Deformation of printing machine parts

In the maintenance process, wear and tear is one of the main factors of mechanical damage, but the parts of the trace deformation is easy to ignore, often after the repair of the worn parts assembled, the machine technical performance is not up to the requirements. This is related to metal deformation. In actual production, the base part deformation to pay special attention to, because if the base part deformation, will affect the interrelationship of all parts assembled on the base part and the mechanical properties of the mechanism. So in the process of repairing parts, both to check the mating surface wear, but also to check the parts (especially the base parts) mutual position accuracy? For the first overhauled mechanical deformation, be sure to keep an eye on it under the action of internal stress, 12 to 20 months later whether there is deformation. For the hot-processed parts, there should be appropriate measures to remove internal stress.

③Disassembly and assembly of printing machines

Mechanical repair personnel to repair printing machinery, are faced with disassembly and assembly problems, especially assembly, will directly affect the mechanical performance of good or bad, assembly quality is not high, will cause serious wear and tear of machinery.

a)Disassembly of machinery

Since there are many types of printing machines and different shapes of parts, it is difficult to describe them all. Here introduces the general principles of disassembly. First, before disassembly must understand the structure of machinery, role and principle, first consult the relevant technical information and instructions. From the practical point of view, determine the disassembly part, can not be disassembled part should not be disassembled as far as possible, but for not disassembled part, must be after the overall inspection to ensure the quality.

Second, in the disassembly process should be used from the table to the order of disassembly, first disassemble the external accessories, oil pipes, etc., and then disassemble in accordance with the order of the assembly after the parts, for the more important parts with the location, disassembly to make a mark, list the number, do not disorderly stacking. In the disassembly of reasonable use of tools is also very important, tools must be compatible with the parts being disassembled. Such as disassembly of threaded connections to use the appropriate wrench, disassembly of static fit parts to use special tools, do not hammer, pry indiscriminately, etc.. In addition, disassembly should create conditions for assembly, non-interchangeable parts, disassembly should also be well marked or placed in pairs, so that assembly reset, so as to ensure the accuracy of assembly and reduce unnecessary wear.

b)Assembly of machinery

Assembly must ensure the fit accuracy and dimensional accuracy, in order to ensure the fit accuracy, in the assembly can be used to match method, repair method and adjustment method. Dimensional accuracy mainly refers to the degree of error in the assembly of each part of the assembly size, that is, in the assembly, attention should be paid to the elimination of cumulative error, to avoid adverse effects on the machine due to the increase in cumulative error.

Sealing in the assembly is also very important, in the printing machine, the seal is mainly used in the air pump, gear box and other parts, seal failure will occur when the leakage of air, oil leakage phenomenon. Therefore, the seal material selected in the repair should be appropriate, assembly should be reasonable, the choice of liquid sealant for static seal storage, according to the nature of the use of different, respectively, dry adhesion type, dry peelable type, non-dry sticky type and semi-dry viscoelastic type and other varieties.

The preparation work before assembly must not be neglected, its content includes pre-assembly inspection, assembly cleaning and assembly of components. The last is the test run after assembly, its role is two, one is to check the quality of the assembly; the second is to adjust the machinery.

c)Cleaning of mechanical parts

The cleaning of mechanical parts is the indispensable part of the machine repair, cleaning content is mainly oil removal and rust removal. Degreasing cleaning methods are mainly alkali solution degreasing method, organic solvent degreasing method and metal cleaning Ji degreasing method three. Here the alkali solution, mainly added to the emulsifier alkali solution, it has a good effect for cleaning mineral grease. The so-called machine solvent generally refers to gasoline, kerosene, etc., which can dissolve a variety of grease, without damaging the parts, in addition to gasoline, kerosene, the precision of the fine parts, bonded parts, respectively, can use alcohol, acetone, ether and other organic solvents. Metal cleaning Ji is a new type of synthetic detergent, due to the base surface active substances to reduce the interfacial tension and produce wetting, penetration, emulsification, dispersion and other effects, so that it has a very strong decontamination ability. The use of this detergent non-toxic, non-corrosive, non-combustible, non-explosive, non-polluting, and a certain degree of rust prevention ability, the cost is also lower, and has been widely used.

Rust removal and cleaning methods are mainly mechanical and chemical methods. Mechanical rust removal is generally carried out with wire brushes, scrapers, abrasive cloths, etc. Sometimes, electric grinding wheels and wire wheels are also available. Mechanical rust removal is easy to leave scratch marks on the working surface and is only suitable for surface rust removal of unimportant parts. The chemical method of rust removal generally uses hydrochloric acid, sulfuric acid and phosphoric acid to remove alkaline metal oxides, which is a simple method with good rust removal effect. When using this method to remove rust, it is necessary to master the concentration ratio of solvents.