Discussion on the Overhaul of Multicolor Machines

It has been nearly 20 years since China imported the first Heidelberg multicolor offset presses from the late 1970s. Early introduction of equipment has entered the old age, and many companies are constrained by funds and other factors. In recent years, a large number of second-hand mobile phones have been introduced to increase the proportion of imported equipment used in the printing industry in China. This situation is expected to continue for a long time. time.
Due to the lack of technical support for maintenance of many enterprises and the lack of funds for equipment maintenance, it is difficult for these old equipment to maintain the high precision and high efficiency it deserves, and it is difficult to print fine products. How to do a good job in the post-management of these old equipment under the limited capital conditions and create the highest economic benefits for the company has become a major issue for many printing companies.
The first Heidelberg 102V four-color machine of our factory was introduced in 1981, and later we have introduced 102V, MOV, SORK (second-hand) equipment. In the long-term maintenance and management of equipment, we have made some efforts. We have successively developed and developed some domestic spare parts, and adopted some advanced technologies and patented technologies during the overhaul. We overhauled a 102V fee of more than 300,000 yuan, which is only 1/2 to 1/4 of the price quoted by professional maintenance companies. The purpose of our major repair is to repair the main, supplemented by the development of domestic spare parts, import the necessary key parts to supplement. After overhaul, the outlets of the 102V machine are well restored, overprinting is accurate, and the overall machine operating performance is good. According to the author's knowledge, some printing companies have spent a lot of money and the overhaul effect is not ideal. This article mainly talks about the work we have done in this area and the experience we have gained. We will start to talk about it and discuss it with our peers.
one. The wear-resistant repair imported brand-name printing equipment, with its high precision and high efficiency, has attracted many printing companies to pay a premium. However, due to the influence of many factors such as management mechanisms, funds, and technology, the long-term operation of equipment caused extensive wear and tear, which has greatly weakened the advantages of these devices. These problems are reflected in the operation, performance performance is poor, the ink balance is not easy to grasp; reflected in the quality of the print product is shown as overprint, mesh distortion, dirty version, paste version. In the long-term equipment maintenance practice, we found that the main causes of equipment overprint accuracy is mainly due to: the positioning roller, impression roller, transfer roller and paper storage roller tooth row shaft wear. If you re-machine the shaft, there are several problems:
1. Differences between domestic and imported materials;
2. Heat treatment fails to achieve the desired target, resulting in lack of comprehensive mechanical properties and surface wear resistance;
3. There are certain technical problems in transplanting nearly 20 boreholes to the new shaft on the original shaft.
Therefore, we mainly adopt repair methods and mainly use chrome-plated repairs. This not only makes full use of the good overall mechanical properties of the original shaft, but also has better wear resistance than other treatments after chrome plating. In this process, we encountered many difficulties and problems, such as the large amount of wear of the shaft, and the maximum wear of the shaft in the radial direction of 1.2 mm, far exceeding the plating thickness (0.4 mm) allowed by the conventional chrome plating technology. The bending deformation of the shaft after long-term stress has brought great difficulties to grinding and chrome plating. In particular, the positioning roller shaft length of 1100mm, the maximum diameter of 16mm, the minimum diameter of 12mm, the middle of 14 steps, the maximum wear of the relevant parts up to 1.05mm, the difficulty of repair is quite large. In the repair process of this type of shaft, we have adopted a patented chrome plating technology, an advanced bending correction system, and a three-dimensional positioning system. In grinding, we have improved the centering device for the grinding machine, using two closed center frames and an open center frame to center the thin shaft. In the chrome plating process, in order to avoid peeling, we use a special chrome plating process. After calibration, grinding, surface treatment, chrome plating and other processes to complete the repair of the shaft, in line with the original parts of the tolerance requirements.
To achieve the accuracy of the dental shaft must be equipped with a copper socket with the same accuracy and wear resistance. We have identified the original active dental braces and developed alternatives for replacement. After the repair... there have been no traces of wear. We have also adopted chrome-plated repair on the swing shaft of the movable roller frame, which is very effective. Through specific practices, we believe that chrome plating is an effective method for the repair of shaft parts.
For the wear of holes, we use the method of insert repair. The abrasion between the water roller bracket and the copper sleeve on the wall plate seriously affects the control and control of the ink balance of the machine. In this regard, we take the approach is to increase the original water roller bracket hole large, and then use ZQSnl0-1 material, according to the diameter of the sliding copper processing. In this way, only the copper bushings can be used to restore the entire set of water roller brackets that are on the verge of end-of-life, and the repair cost is only the material cost and processing fee of the copper bushes.
For the wear of the roller bracket bearing housing, we use the insert repair method, that is, for the worn bearing housing, the outer casing is turned to the root of the worm gear, and the bearing sleeve is machined according to the outer diameter of the bearing, tightly press-fitted into the original. As soon as there is wear, it can be replaced, repaired, and reused, greatly extending its service life and reducing maintenance costs.
Plane face wear can also be repaired by plating. Pulling the linear motion bearing in the gauge seat will cause the wear of the slide due to poor lubrication, which will change the height and movement trajectory of the pull gauge and affect the rules. In this regard, we use universal tool grinding to grind chrome on the wear surface of the gauge seat to restore the dimensions to the new part size. After such a repaired pull gauge seat is superior to the new pull gauge seat in terms of accuracy and wear resistance.
2. Spare parts imported from domestically-made imported spare parts are expensive, and it is imperative to go on the road to localization of military spare parts. However, due to the uneven quality of domestically manufactured parts, many small factories produce spare parts that only have the appearance of imported parts, and their internal quality is not at fault. This is the main reason why many printing companies cannot keep up with spare parts. In this regard, we use our brains to find ways to make use of the advantages of local scientific research and mechanical processing to conduct material identification, heat treatment analysis, and drawing and mapping on imported originals. We use high-precision equipment for processing and manufacturing, and we have improved on-machine testing. Through our efforts, we have successfully developed the CPC ink zone control dosing head, cylinder gripper tooth piece (with rubber), tooth pad, positioning roller tooth piece, pull gauge seat, stringing roller shaft head, feeder platen steel component , Piezoelectric eyes and circuit boards and other consumable parts, enriched the domestic spare parts, so as to improve the normal operation rate of equipment, reduce production and maintenance costs laid a good foundation. The 102V and MOV roller grippers (with rubber) we developed not only overcome the weakness of the original steel to the steel grip, but also greatly increase the grip force and avoid the relative displacement of the paper during the machine impression process. After a few years of wear, the rubber layer can be re-pressed and reused. The wear of the tooth pad is also greatly reduced.
Third, the scientific correction and debugging methods The precision of printing equipment can be compared with the accuracy of space equipment. Therefore, the debugging of Heidelberg machines, especially the transfer and transfer of paper must be completely in accordance with the design data. Any violation of the debugging procedures and data will certainly cause damage to the print quality and even the equipment. These must be prohibited. In this regard, we collected and translated many technical materials on the one hand, and used empirical data to calculate and sum up, summing up a set of effective debugging programs. Use the "fine, accurate, and prudent" three-character principle to ask yourself.
During the maintenance process, we also made bold improvements to the unreasonable parts of the original machine. The relative position between the paper-feeding plate and the positioning roller is the starting point and the reference of the paper from the front stationary positioning state to the mainframe printing, which is a key link that affects the printing accuracy. The flatness of the front end of the Heidelberg machine is less than 0.05mm. In many old equipment, the foreign material enters the front end of the transporter, which causes deformation of the paperboard. The severe partial settlement exceeds 2mm, which seriously affects the printing accuracy and stability. The paperboard material is very rigid and it is very difficult to level it to the specified flatness. To this end, we added 6 adjustable support points on the basis of the original support points, shortening the distance between the adjustment points, and solve this problem.
The main cause of abrasion of the water roller bracket is that the water roller bracket locking device is easy to fail. We have improved this part to make the locking reliable and stable, thus prolonging the service life of the water roller bracket.
In short, good post-management work can extend the service life of equipment, improve the accuracy of equipment, serve production, and increase efficiency; if it is not done well, it may cause old equipment to become a burden to the company and make it useless. It is a pity to give up. I hope that our work in this area and the experience gained will provide useful inspiration and help to our colleagues.