In order to properly evaluate the printing press, printing press manufacturers and printer users specifically request the following three aspects of the printing press.
Work performance
The correct evaluation of the printing machine's performance mainly includes three indicators of overprint accuracy, ink homogeneity and productivity.
1 Overprint accuracy
In the chroma printing process, the accuracy of the overlap of the print is one of the main technical indicators of the printing machine's work performance. In the color printing process, paper transport, transfer, printing, etc., should be guaranteed to be in the specified position at low speed or high speed. This is even more important for fine prints and color printing. This requires that the drive system of the printing press, the transfer position and time of the paper transfer, and the transmission accuracy of the printing plate and the imprinting mechanism should meet certain requirements. Therefore, when we analyze the printing press, we must focus on understanding the various links related to overprinting accuracy, grasp its characteristics and its role.
2 Ink color is uniform
Ink uniformity refers to the consistency of the ink layer thickness of the ink and the clarity of the ink. This is another indicator of the quality of the printed product, and is also an important content for evaluating the performance of the printing press. No matter which printing method is adopted, printing ink with clear and firm ink should not only require uniform ink color, but also need sufficient printing pressure. This requires that the printing device, including the inking system, should have high accuracy and performance. .
3 Productivity
The productivity of a printing press is generally expressed in terms of printing speed. The printing speed is expressed in sheets/hour for a sheet-fed printer and m/min for a web-fed printer. The structure and characteristics of the printing press and the technical level of the automatic control system are the main factors that determine the productivity. For example, the flattening press uses an impression cylinder. The printing speed of the flattening press has been significantly improved. However, the reciprocating motion of the platen has limited the further improvement of productivity. Therefore, it has gradually been printed in circular presses. Machine instead. At present, the printing press is developing toward large-scale, high-speed, and linkage, so as to maximize productivity.
Use performance
The performance of the printing press includes operational performance, safety, reliability, and durability.
1 Operational performance
While improving the printing speed and automation of the printing press, good operating performance must also be ensured.
The printing press generally covers a large area and several sets of operating panels should be provided to ensure that the operator can operate in every major working position. Each operating platter must conform to people's movement habits, the working position is easy to observe, and the adjustment parts are intuitive and easy to contact.
2 safety and reliability
In order to ensure the safety of the operator's personal and equipment, in addition to the safety protection device on the printing press, there must also be a safety protection device. In addition, a safety protection device should be provided to automatically stop the machine if it fails.
3 durable performance
The long-term use of printing presses can also maintain their original precision, that is, the machine has a long service life, which has important economic significance for both countries and enterprises. To achieve this, reasonable selection of parts materials and heat treatment process to ensure the wear resistance of the parts; in order to improve the movement accuracy of the transmission system, each fitting surface should have a reasonable number of body shape accuracy and good fit clearance and lubrication device Wait.
Process performance
Under the premise that the printing press satisfies the main work performance, it should strive for its simple and compact structure, good processability, reduced manufacturing cost, and ease of assembly and maintenance.
It should be pointed out that the above requirements are often restricted and contradictory to each other. For example, to improve the accuracy of overprinting, it is not easy to achieve under high-speed operation. Because the printing speed is further increased, it will bring some new problems: the rapid and accurate transfer and transfer of paper, the quick drying of ink and the smoothness of moving parts will be greatly affected, making it difficult to guarantee the accuracy of overprinting. The addition of a control device will increase the cost of manufacturing the machine. For another example, there is a certain contradiction between the simple structure and the increased degree of automation, between printing speed and service life. Therefore, we can only take the above requirements as the starting point of the analysis problem, according to the requirements of the printing process on the machine, grasp the main contradiction and weak links, weigh the whole from the overall point of view, and properly solve the minor contradiction on the premise of meeting the main requirements. This is also the way to study the design of printing presses should follow.
Work performance
The correct evaluation of the printing machine's performance mainly includes three indicators of overprint accuracy, ink homogeneity and productivity.
1 Overprint accuracy
In the chroma printing process, the accuracy of the overlap of the print is one of the main technical indicators of the printing machine's work performance. In the color printing process, paper transport, transfer, printing, etc., should be guaranteed to be in the specified position at low speed or high speed. This is even more important for fine prints and color printing. This requires that the drive system of the printing press, the transfer position and time of the paper transfer, and the transmission accuracy of the printing plate and the imprinting mechanism should meet certain requirements. Therefore, when we analyze the printing press, we must focus on understanding the various links related to overprinting accuracy, grasp its characteristics and its role.
2 Ink color is uniform
Ink uniformity refers to the consistency of the ink layer thickness of the ink and the clarity of the ink. This is another indicator of the quality of the printed product, and is also an important content for evaluating the performance of the printing press. No matter which printing method is adopted, printing ink with clear and firm ink should not only require uniform ink color, but also need sufficient printing pressure. This requires that the printing device, including the inking system, should have high accuracy and performance. .
3 Productivity
The productivity of a printing press is generally expressed in terms of printing speed. The printing speed is expressed in sheets/hour for a sheet-fed printer and m/min for a web-fed printer. The structure and characteristics of the printing press and the technical level of the automatic control system are the main factors that determine the productivity. For example, the flattening press uses an impression cylinder. The printing speed of the flattening press has been significantly improved. However, the reciprocating motion of the platen has limited the further improvement of productivity. Therefore, it has gradually been printed in circular presses. Machine instead. At present, the printing press is developing toward large-scale, high-speed, and linkage, so as to maximize productivity.
Use performance
The performance of the printing press includes operational performance, safety, reliability, and durability.
1 Operational performance
While improving the printing speed and automation of the printing press, good operating performance must also be ensured.
The printing press generally covers a large area and several sets of operating panels should be provided to ensure that the operator can operate in every major working position. Each operating platter must conform to people's movement habits, the working position is easy to observe, and the adjustment parts are intuitive and easy to contact.
2 safety and reliability
In order to ensure the safety of the operator's personal and equipment, in addition to the safety protection device on the printing press, there must also be a safety protection device. In addition, a safety protection device should be provided to automatically stop the machine if it fails.
3 durable performance
The long-term use of printing presses can also maintain their original precision, that is, the machine has a long service life, which has important economic significance for both countries and enterprises. To achieve this, reasonable selection of parts materials and heat treatment process to ensure the wear resistance of the parts; in order to improve the movement accuracy of the transmission system, each fitting surface should have a reasonable number of body shape accuracy and good fit clearance and lubrication device Wait.
Process performance
Under the premise that the printing press satisfies the main work performance, it should strive for its simple and compact structure, good processability, reduced manufacturing cost, and ease of assembly and maintenance.
It should be pointed out that the above requirements are often restricted and contradictory to each other. For example, to improve the accuracy of overprinting, it is not easy to achieve under high-speed operation. Because the printing speed is further increased, it will bring some new problems: the rapid and accurate transfer and transfer of paper, the quick drying of ink and the smoothness of moving parts will be greatly affected, making it difficult to guarantee the accuracy of overprinting. The addition of a control device will increase the cost of manufacturing the machine. For another example, there is a certain contradiction between the simple structure and the increased degree of automation, between printing speed and service life. Therefore, we can only take the above requirements as the starting point of the analysis problem, according to the requirements of the printing process on the machine, grasp the main contradiction and weak links, weigh the whole from the overall point of view, and properly solve the minor contradiction on the premise of meeting the main requirements. This is also the way to study the design of printing presses should follow.
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