Analysis of the Test Questions of the Workers' Group (Single Sheet) in the Vocational Skills Competition
After repeated discussion and research, the technical expert group of the contest believed that the contest should not only identify the player's practical ability, but also the player's comprehensive business ability. Therefore, he decided to open the construction order, identify the printing plate, prepare the double color ink, and product printing , The use and calculation of density meters, quality detection and evaluation, fault analysis and elimination of seven aspects to assess the comprehensive skills of players.
1. Organizing the test questions
As early as 2007, the China Printing Technology Association started the preparations for the contest. First, it formulated and promulgated the new "Lithographic Printer" National Professional Standard. Then, for the 2008 competition to be successfully held, more than 100 technical backbones from various provinces and cities across the country were given the "Lithographic Printing Worker" national professional standards and national referee training. The assessment of the theoretical knowledge (should know) and skill operation (should be) of the contest are all closely focused on the national vocational standards of "Lithographer", especially the actual operation part, considering that most of the regions and enterprises currently have The introduction of foreign advanced multi-color lithographic printing machines, these devices have a high technical content, only rely on one product printing, there is a great chance, may not fully reflect the true level of players, for this reason, the technical expert group of the competition has repeated many times After discussion and research, it was considered that the contest should not only identify the player's practical ability, but also the player's comprehensive business ability. Seven aspects of quality inspection and evaluation, fault analysis and elimination are to assess the comprehensive skills of players.
Second, the selection of printed proofs
After the contest project is formulated, the selection of proofs is the primary task of the contest. The organizing committee organized a number of experts to put forward various plans. Finally, after careful review and demonstration by the expert group, a feasible plan was proposed: the proofs were both difficult and operable. It was decided to choose from the following 4 alternative proofs The picture serves as a competition proof.
The proofs adopt 880 × 590 large format, which is composed of two quadruple patterns, side by side with a calendar table, four sides with y30%, m27% and c40% network cable synthesis blue gray frame, the second background color is 95% magenta, 95 % Yellow (the right picture plus 30% blue) is the main color to set off the copper tripod and porcelain, and the main colors of these two paintings are different from the warm and cold, including the amount of ink used in the calendar next to the main image will affect the entire border Gray balance. The reason for choosing this pair of competition proofs is mainly to assess how the players can handle the color in the printing process, not only to restore the gradation level of the proof pattern, but also to deal with the uniformity of the border ink color gray balance. Judging from the internal layout of the sample in Figure 1, the following key difficulties need to be addressed:
(1) The main colors of the copper tripod and porcelain should be treated with their red background colors;
(2) The red background color of the two main bodies should be handled well with the frame, and the color cannot be cast;
(3) The calendars on the sides of the two main bodies use a relatively small amount of ink, and should be evenly processed with the gray balance of the surrounding borders;
(4) As the gray balance borders around the screen, how to prevent "ghosting" during operation;
(5) Maintenance and adjustment of equipment. Avoid "ghosting", "dark front and back light", "water and ink streaks", etc. affecting the printing quality.
(6) According to the contrast of the proofs, the gradation level and the intact state of the enterprise equipment, select and determine the best exposure time for printing to meet and achieve the best printing effect.
In this competition, the contestants need to first maintain and adjust the equipment used before the competition; then they can determine the exposure time according to the requirements of the proofs before printing, and finally deal with the "water-ink balance" when printing, in order to ensure the picture On the basis of the theme ink color conforming to the proof, it is also necessary to ensure that the ink color of the surrounding border and the middle frame line is uniform, and there must be no color drift. Dealing with the above problems does have certain skill requirements and difficulty for the contestants. It also fully reflects the contestants' equipment maintenance, adjustment level and actual operation ability in the competition before the competition.
3. Comprehensive quality assessment
1. Open construction order
The product construction order is to transfer the voucher of the customer's product instructions and requirements to the machine. The operator must fully understand and master the production requirements and process measures described in the construction order before printing. In this competition, participants are required to formulate basic process requirements for each production section based on the product samples provided.
(1) First determine the paper specifications, varieties and machine specifications, and printing extensions based on the provided samples of finished products; it is required to understand and write out the processes in the production process, such as the number of extensions, not only consider the extension of printing, Also consider the extension of post-press processing, such as glazing, laminating, bump bronzing, die cutting and paste box molding. At the same time, the quality of the cut paper requires support (such as upper and lower knife errors). According to the size of the sample sheet, it can be considered from the lowest cost, and indicate the best imposition on the machine for printing.
(2) Different products will have different requirements in the printing version. Therefore, according to the proofs, the printing quality requirements are made to the printing department. This construction single sample is a molded packaging box. There is a one-time printing or a second set of printing, which requires accurate specifications, status and size, all kinds of rules are in line, and indicates that the outlets are complete and full, and the field requires plain clothes, etc. .
(3) Printing process requirements, according to the proofs, confirm the printing color number and printing color sequence, this competition has three appearances, including front and back two-sided printing, also single-sided printing, there are local uv glazing, bump gold or stamping Silver, therefore, it is required to understand and consider the post-press processing technology during printing to prevent difficulties in post-press processing. For example, when making specifications, it is necessary to consider the position of the box overlap. When coating is required on the rear surface, the amount of powder sprayed and moisture control should also be taken into consideration during printing to avoid blistering and deformation of the coating. Some players can also write a clear logo after printing specifications are changed, indicating that these players are quite familiar with the entire product processing process.
(4) Printing quality, according to the requirements of printing proofs, we can put forward the quality requirements during printing and processing, regardless of overprinting, color reproduction, etc., we must meet customer requirements.
(5) Post-press processing requirements. Participants are required to accurately formulate post-print finishing processing procedures and processing technology requirements based on the proofs. A senior technical talent must have an understanding of the post-print finishing processes. From this competition, it can also be seen that some players in this area It is relatively weak and needs to be strengthened and improved.
(6) Finished product inspection. Most players have knowledge and support of the quality inspection requirements before leaving the factory.
(7) Others. Mainly in addition to the operation procedures of the entire production process from product proofs to printing to post-press processing and finished product delivery, and then to the packaging, boxing, loading and unloading transportation and other aspects of the delivery process after finished product inspection. Through this competition, it was reflected that many players lacked such comprehensive knowledge and only mastered the production technology requirements of the main production links, while ignoring the coordination between product production and the understanding and mastery of the entire product production process.
Contests are issued with construction orders to check how much knowledge the players have in practical aspects of product production and processing. Not only do they need to be able to understand and master, but they also need to be able to put forward their own opinions on the areas of the construction process that are not perfect in actual production. And amendments to fully demonstrate their technical talents.
2. Preparation before printing
(1) Identification of printing plate colors and shades
As a leader or a mature technical worker, the color of the printing plate and the quality of the printing plate must be reviewed before the product is put on the machine to avoid unnecessary errors and losses. As usual, four printing plates and prints of y, m, c, and k are generally used to identify colors, but this time, three colors are selected from the four colors of y, m, c, and k, so that one of the colors The printing plates are repeated, and the two repeated printing plate dots are divided into deep and shallow dots, which should be distinguishable.
This time, there are three sets of test versions a, b, and c in this project. The three sets of printing plate patterns are mainly high and low-grade outlets, and the middle level is relatively small. It is difficult to identify these three sets of printing plates. Players choose to draw. This item is mainly to check whether the players can identify the color of the printing plate and the printing plate's darkness according to the proofs.
(2) Identification of printing plate quality
Three sets of printing plates with quality defects were also prepared, and players were required to find and analyze the quality defects and causes according to the sample within the specified time. Among them, some of the layouts were in the wrong position of the printing specifications, color standards, and rules. The film is stained or scratched during printing, or the text or internal image is damaged when the stain is removed after printing, until the printing plate surface is scratched or has a concave phenomenon.
The identification of printing plate quality is to check whether the players are familiar with and master the quality requirements and process requirements of the previous printing process, and can also avoid unnecessary errors and losses.
(3) Preparation of spot color ink
The competition requires players to complete the preparation of two kinds of dark and light spot color (multicolor) ink within 15 minutes. The purpose of the assessment of this project is mainly to adjust the ink to see the player's mastery of color and the proficiency of color in printing. It is also how to master the color according to the proofs in production, especially when printing multi-color spot ink, it is particularly important to master the color. Although some enterprises have special personnel to adjust ink, many regions and enterprises rely on machine operators to adjust special inks themselves. Therefore, as a senior engineer and technician, you must master the principle of color and the ability to prepare spot color ink.
3. Implement printing
(1) Preparation before printing
This competition stipulates that players perform operations without proofs during printing, and requires players to observe and analyze the proofs for 15 minutes before printing, including memorization of signal bars, printing color sequence arrangement, ink volume control, gray balance Mastering and so on are all examining the true level of players. This is very difficult for many players, and it is also an important factor in the big score between players in this competition.
(2) Ink preset system
In this competition, the a and b versions are used, and the same film is used, but the bite and the drag are turned to the plate. In fact, the bite and the drag pattern are crossed and reversed. The printing plate used by the previous player and the next player are used. The printing plates are reversed. The printing plates are used in front and back. The layout of the ink volume is not the same. The ink flow of the printing plate is disrupted. The players should readjust the ink volume to ensure the fairness and justice of the competition. In the competition, many players pre-set the ink volume on the computer-controlled console based on the gradation level of the proofs and layout patterns, and basically reached the printing pattern before the official printing, which fully reflected that many players are still quite experienced and level.
(3) Printing
Product printing accounts for 50% of the entire skill practice. From the beginning of the competition to the end of printing, the contest stipulates that players should complete 1,000 (offset) printing within 30 minutes. Among them, there are three main assessments. First, the first printed sample (installed sample) after the version is installed, is used to investigate the preparation and proficiency of the competitors before the version is installed. Secondly, after the official opening of the press, one sample will be drawn for every 200 prints, and a total of 5 evaluation samples will be drawn for 1000 copies. From the first to the fifth appearance, the trend of ink color control during the printing process will be stable. How well, including water-ink balance control and product quality control in the printing process. In the end, the contestants will take a picture of themselves before the end of the printing. As a self-selected sample evaluation, this sample is very important, accounting for 32% of the total printing score. The color reproduction and control of the sample, the accuracy of the plate mounting and overprinting, the ink and ink balance The gray balance control of the frame is based on the evaluation of the optional samples, and the actual operation ability of the players can basically be seen.
4. Quality Evaluation
(1) According to the test areas, segments, and blocks with different functions on the third generation of Brunner's measurement and control strips, the signal strips are used to calculate the dot expansion value, overprint rate, and relative contrast of the dots through the data measured by the density meter on the color block. (Choose one out of three).
We know that the measurement and control strip is an important medium for the implementation of color printing quality data control. It can reflect the changes of dot expansion or contraction in product printing in time, the relative contrast of printing and the printing overprint rate, and also reflect the exposure control and plate map during printing. The resolution of the text. Therefore, players are required to correctly select the test area, segment, and block according to the requirements of the test questions, then accurately write the calculation formula of the dot expansion value, relative contrast, or overprint rate (one of them), and finally select the selected according to the requirements of the question. The data on the signal block is substituted into the formula to finally calculate the value.
The assessment of this project requires players to be proficient in using equipment and equipment, and accurately select test areas, segments, and signal blocks for quality detection and calculation. At present, many well-managed enterprises use digital data for scientific management in production management, and use data for product quality. Change the past to use visual inspection and experience to judge the quality of the product, so it puts forward new requirements for players and enterprises to strengthen scientific management in the new situation.
(2) Evaluation proofs. Players are required to check the density on the ground with a density meter or based on their own actual experience, to conduct quality analysis and evaluation of the self-selected sample control sample in practice. Many players can see the gap between the ink color control and the gray balance control in the operation through the sample comparison. Through such comparison and evaluation, the player has been greatly improved, and it is also the ultimate goal of the competition.
5. Failure analysis
In actual production, there are often process failures or mechanical equipment failures. The effect of timely resolution of the processing failures reflects the actual ability of the operator. However, in the past, troubleshooting assessments on the scene of the competition will be restricted by various conditions, and it is even more impossible to set the mechanical failure assessment player troubleshooting capabilities on the normally produced machines. Therefore, according to the opinions of experts, a written answer is used to complete the assessment of the ability to solve the fault.
This time there were 5 questions, of which 2 out of 5 were selected, only required to complete the 2 questions specified.
The first question: when the proofreading is not correct before printing, what aspects should be analyzed and solved.
The question is about the inaccuracy of the school after the last edition, mainly the inaccuracy of the internal map or the crosshair set, which is two different issues from the inaccuracy of the normal printing in normal production. In the investigation, it can be seen from the players' answer sheets that many people can consider the pre-press plate making (imposition, copying), plate-setting operation, materials and equipment, which basically meet the requirements of the question.
The second question: new equipment should be checked and accepted after entering the factory.
The question requires that after the new equipment enters the factory, the machine will be tested for the machine after the completion of the work such as the position of the machine and the power connection. Only the players are required to answer the acceptance items and acceptance requirements. In the past, there was a question: What kind of acceptance preparation work should enterprises do for new equipment? These two questions look similar. They also require installation, commissioning and acceptance of new equipment, but many preparations must be made before the new equipment enters the factory, such as the preparation of the host machine foundation, equipment power distribution, water pipe discharge, test version production, etc. , Must be completed before the new equipment enters the factory. This time I did not ask to answer all the preparations before the equipment entered the factory, but mainly the commissioning and acceptance after the equipment was installed. Through this exam, some started from the preparations before installation to the commissioning and acceptance of the project, and some Start debugging after the machine is installed and in place, and I don't really understand the problem.
Everyone's debugging projects are basically around the cross-printing (same speed and different speed), printed full version (with water full version), printed network cable and other items for debugging, but there is still no unified standard in the acceptance criteria. The printing business and product structure of each enterprise are related, and the quality requirements are different.
The first national printing industry vocational skill competition was successfully concluded years ago. The participating enterprises, contestants and referees have been learned and improved throughout the competition process or the results of the competition. At the same time, they also exposed the current industry-oriented theory Prejudice has attracted the attention of organizations at all levels and relevant leaders. It will set off a new upsurge of learning technology theories and exchange technology in the printing industry across the country. It will stimulate and promote the development of post-employees towards technical skills, knowledge skills, and compound skills. At the same time, it will also promote technical training for industry employees. The above are some personal experiences and feelings in the skill operation competition of the staff group (flat paper) of this competition, and we will discuss with you.
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