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Large format flatbed printing machine can it be used after modification?

Most of the large format flatbed printing machines are modified from EpsonPro4800 inkjet printers. In this article, we will talk about the principles of flatbed printer conversion and what problems need to be paid attention to 
during the conversion process based on practical experience!

Digital printing machine

1. Modification principle

Lead the digital printing machine drive signal of the pickup motor, and then add a power amplifier to drive a larger stepper motor. Then move the position of this motor to another platform, and move the working platform or printer 
body through the screw, timing belt, and steel wire. In fact, the pickup motor is converted into a Y-axis motor (control machine, ink cart e Move back and forth) only. The paper pick-up mechanism of the modified machine itself is basically useless. Without affecting the structural strength of the printer, the shaft stick can be removed or sawed to make the lower space available for the working platform. When the printer starts to work, a photoelectric sensor is used to check whether there is paper. When the flatbed printer is simply modified, this sensor needs to be moved to the working platform to detect whether the platform is close to the printer. Similar to the printer detecting the paper can be printed, this time, the printer will work. This sensor can be replaced with a proximity switch, which makes it easier to handle the installation position of the sensor. A more complicated modification is 
to process some things through the single-chip microcomputer, for example, you can send a virtual paper sensor signal to the printer, trick the printer to print directly, and control whether the printer is "offline" or "online" with the 
host computer (similar EpsonLQ1600K's old-style printer's panel operation mode) can also control the independent work of the Y-axis motor, move the platform or the printer separately, so this function is needed in certain debugging states.

2. Modification accuracy

Regarding the existing modification methods and conditions, the accuracy that everyone can talk about is limited to the static dot matrix accuracy of the nozzle. After the modification, the only thing that can guarantee the accuracy on the machine is the dragging part of the ink cart on the original machine. We can regard it as the X-axis part (controlling the left and right movement of the machine and ink cart). Because the printer usually has plastic grating tape for position feedback, this accuracy is still very high. There are also some old machines that use an open-loop stepper motor to drive the ink cart. This accuracy can only be guaranteed by the stepper motor itself. However, because the accuracy of each step angle of the stepper motor is relatively high, and the error does not accumulate, although this kind of drive is worse than the accuracy with feedback, it is also quite good. The accuracy of the horizontal movement of the Y-axis part can be guaranteed because the stepper motor is also used. The least guarantee is the accuracy of the up and down position of the platform. We can regard this position as the Z axis (moving up and down relative to the machine and the ink cart). Generally speaking, everyone adjusts the position of the platform away from the printer manually, and it is basically visually inspected. This error is very large. Therefore, you should not be fooled by the figure of precision when you modify a flatbed printer. What can be guaranteed is that the X-axis ink cart dragging part that everyone does not move in the printer itself, and the horizontal moving part of the Y axis, the Z axis cannot be used to talk about accuracy. The concept of accuracy should also be viewed from many aspects. If the Y axis after modification is very long, then the accuracy will be relatively low. Some friends said that the accuracy is guaranteed to be 0.02mm, then the error is ±0.01mm, this accuracy is very high, this It is the level that high-precision industrial machine tools can achieve! If the machine frame is a high-rigidity machine tool frame, which has passed the aging treatment and passed a high level of debugging, it may be possible to install it in a constant temperature and humidity workshop. However, as far as everyone is now in the way of modification, this number is artificially high, and it is not practical. There is a suspicion of commercial hype. Saying such accuracy can only show that everyone does not know much about the mechanical knowledge.

3. Modification method

Everyone is now refitted with two methods: printer fixing, work platform moving, printer moving, and work table fixing. Now let's compare the characteristics of these two methods. In the first way, the printer is fixed. In order to ensure the printable length of the platform in the direction of the Y axis moving forward and backward, the platform will be much longer than the platform used in the second way. Looking at the distance between the two rail sliders used to fix the platform, in general, it will grow about half the length. If the rigidity of the rail and the platform is sufficient, this size can be appropriately reduced. Therefore, the area of the machine modified by the first method will be larger than that of the second method, which is mainly reflected in the space for the Y-axis platform to expand and contract. This movement method of platform movement is widely used in industrial machines. The 
main reason is that this method can ensure high body strength and processing accuracy, while the method of printer movement is not required for high accuracy and requires space. There are many applications on civilian 
products. As for the small-sized machine (A4), it is simpler to modify it by using the platform movement method. You can use a light platform, and use the printer's pickup motor to directly drive the platform to move, so the 
workload of the modification is much smaller and grows by one. The space occupied by double the platform is basically negligible. If the room space is not very large, I tend to use the printer to move, which can save space. In 
the case of retrofitting flatbed printers, the accuracy requirements are very low relative to the accuracy of industrial machine tools! The two methods have no effect on the printing accuracy, youcan choose according to the actual 

Large format flatbed printing machine

4. Drive modification details

The Y-axis driving part of digital inkjet printer is the signal from the pickup motor. Whether it is platform movement or printer movement, the speed of this linear movement must be thoroughly guaranteed, so as to ensure that the length of the printed graphics does not change. This needs to calculate the speed ratio of the original pickup mechanism, and then reflect it on the modified Y axis through various deceleration methods. The ways to change the gear ratio are roughly: gear shifting, synchronous belt shifting, worm gear shifting, rack and pinion shifting, etc., ball screw shifting is a kind of gear shifting, which is the most common way, but the cost is the highest. And its transmission ratio is fixed, if it does not meet the requirements, you need to add a timing belt or gear set to adjust the transmission ratio. The modified Y-axis torque transmission methods are usually: screw drive, steel wire drive, synchronous belt drive, rack and pinion drive. In general, the cost of the ball screw drive in the screw drive is the most expensive and accurate It is the highest, because the precision requirements of the machine modification are not very high, do you have to choose this ball screw, you can choose according to your own economic situation. The above are from the mechanical point of view to consider the problem of variable speed, and the variable speed can be considered from the electrical point of view. This is to use a stepper motor with feedback or a more advanced servo motor. Both types of motors have feedback. It is plc to adjust the speed of the motor, which can completely achieve the effect of speed change. Of course, this requires a relatively high level of knowledge for those who are converted.