Real-time monitoring system and method for ink ejection amount of 3D printing device

Abstract

The application discloses a kind of 3D printing equipment ink-jet quantity real-time monitoring system, belong to the field of additive manufacturing, to solve the problem of real-time monitoring inaccuracy of ink-jet quantity of additive manufacturing equipment in printing process, including printing mechanism, ink storage mechanism, data acquisition device and host computer, the printing mechanism is arranged on the 3D printing equipment, to realize the ink-jet printing of the 3D printing equipment;The ink storage mechanism is arranged below the printing mechanism and is in the operating range of the printing mechanism;The data acquisition device is arranged on the ink storage mechanism, and there is also communication connection between the ink storage mechanism, the host computer is connected with the data acquisition device, the printing mechanism and the ink storage mechanism between communication connection.The application detects the weight of each nozzle ink-jet in unit time periodically in printing process, realizes the monitoring of nozzle ejection rate in printing process, and the ink addition ratio of current 3D printing part can be indirectly calculated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of additive manufacturing technology, in particular to an additive manufacturing device. BACKGROUND

[0002] An inkjet 3D printer is a special equipment that realizes powder material bonding forming through binder jetting technology. The change of inkjet amount (such as ejection rate, ink droplet volume) of the printer nozzle is crucial to the forming effect of the 3D printed part. Generally, large and medium-sized 3D printers adopt array type nozzle structure, that is, multiple nozzles are assembled into a whole large-width nozzle through splicing. However, in the actual printing process, when a certain nozzle fails to jet ink normally or has a low ejection rate, it is often difficult to find out, resulting in the final printed product being scrapped due to the ink jetting problem of the individual nozzle.

[0003] The addition ratio of the binder in the 3D printed part directly affects the strength of the 3D printed part. The proportion of ink in the unit weight of the product to be printed is called the ink addition ratio. At present, the calculation methods of the ink addition ratio of the 3D printer mainly include offline calculation and online detection. The offline calculation method assumes that the ink droplet volume of the nozzle remains unchanged, and calculates the ink addition ratio of the 3D printed part through a theoretical formula; the online detection method generally installs a flow meter or other detection unit on the ink supply pipeline of the printer to detect the total ink consumption of the printer, and then calculates the ink addition ratio according to the total mass of the product to be printed. However, in the above two methods, the offline calculation method cannot solve the real-time resin addition ratio detection problem caused by the change of ink droplet volume due to changes in the environment or printing parameters; the online detection method cannot accurately detect the small amount of ink consumption when printing small parts. SUMMARY

[0004] In view of the above problems that the online detection of inkjet amount is not convenient and inaccurate for products with small volume or weight, it is necessary to propose a real-time monitoring system and method for inkjet amount of 3D printing equipment to realize online real-time monitoring of inkjet amount of any product.

[0005] A real-time monitoring system for inkjet amount of 3D printing equipment, comprising a printing mechanism, an ink storage mechanism, a data acquisition device and an upper computer, wherein the printing mechanism is arranged on the 3D printing equipment to realize inkjet printing of the 3D printing equipment; the ink storage mechanism is arranged on the 3D printing equipment and is below the printing mechanism in the monitoring state; the data acquisition device is arranged on the ink storage mechanism and has a communication connection with the ink storage mechanism to transmit the data of the ink storage mechanism to the upper computer; the upper computer is in communication connection with the data acquisition device, the printing mechanism and the ink storage mechanism to receive or issue relevant information or instructions.

[0006] Preferably, the ink storage mechanism comprises an ink storage box, a weight detection unit and a mounting platform, the mounting platform is arranged on the 3D printing device, the weight detection unit is arranged on the mounting platform, and the ink storage box is arranged on the weight detection unit, and the weight detection unit is used to weigh the weight of the ink storage box.

[0007] More preferably, the ink storage box and the weight detection unit can be one-to-one correspondence, that is, one weight detection unit is arranged below each ink storage box to weigh the weight of each ink storage box; alternatively, several ink storage boxes share one weight detection unit, that is, one weight detection unit is arranged below several ink storage boxes, thereby reducing the amount of weight detection unit and the manufacturing cost of the real-time monitoring system.

[0008] More preferably, the accuracy of the weight detection unit can distinguish 1% of the ink increase; at the same time, the maximum range of the weight detection unit is not less than the total weight of the ink flashed during the printing of the largest product by the 3D printing device, and the ink storage box can accommodate all the ink flashed during the printing of the largest product by the 3D printing device.

[0009] More preferably, the connection relationship between the weight detection unit and the ink storage box can be that the ink storage box is directly placed on the weight detection unit, or a clamping, magnetic or other connection mode is used between the two. Specifically, the distance between the upper edge of the ink storage box inlet and the nozzle outlet of the printing mechanism is equal to the distance between the nozzle of the printing mechanism and the powder laying surface, or the inlet of the ink storage box is in the same horizontal plane as the powder laying surface or the plane where the inlet of the ink storage box is in the same horizontal plane as the working surface of the printing mechanism.

[0010] More preferably, the mounting platform is further provided with a level measurement unit, the weight detection unit is arranged on the surface of the mounting platform facing the printing mechanism, and the level measurement unit is used to adjust and detect the levelness of the mounting platform to ensure that the weight detection unit is in a horizontal position and ensure the accuracy of ink weight detection.

[0011] More preferably, the ink storage box corresponds to each nozzle of the printing mechanism one by one, that is, each nozzle of the printing mechanism is provided with one ink storage box, or each nozzle corresponds to one ink storage box to collect the ink flashed by an independent nozzle; alternatively, several nozzles are provided with one ink storage box to save the space occupied by the ink storage mechanism and facilitate the arrangement of the ink storage mechanism on the 3D printing device.

[0012] A real-time monitoring method for ink ejection amount of a 3D printing device, comprising,

[0013] 1) the printing mechanism normally prints the job according to the printing data;

[0014] 2) a flash ejection job is performed at the ink storage mechanism according to a set frequency;

[0015] 3) the weight detection unit weighs the weight of the ink storage box after the current flash ejection;

[0016] 4) in the case of each nozzle being provided with an independent ink storage box, the weight difference between the weight m2 of the ink storage box after the current flash ejection and the weight m1 of the ink storage box before the current flash ejection is obtained, and the difference result is the ink ejection amount of the current flash ejection, denoted as Δm = m2-m1;

[0017] 5) if the difference or ratio between the ink ejection amount Δm of the current flash ejection and the set ink ejection amount Δm0 is within the set variation range, the ink ejection amount of the corresponding nozzle of the printing mechanism is within the normal operation range, and the printing mechanism continues the next printing job; if the difference or ratio between the ink ejection amount Δm of the current flash ejection and the set ink ejection amount Δm0 exceeds the set variation range, the ink ejection amount of the corresponding nozzle of the printing mechanism exceeds the normal operation range, and the printing mechanism performs automatic adjustment;

[0018] 6) after the automatic adjustment, the printing mechanism is started again for flash ejection, and the difference between the weight of the ink storage box after the current flash ejection after the automatic adjustment and the weight of the ink storage box before the flash ejection before the automatic adjustment is compared again, i.e. the ink ejection amount of the printing mechanism after the automatic adjustment is Δm', if the difference or ratio between the Δm' and the Δm0 is within the set variation range, the ink ejection amount of the corresponding nozzle of the printing mechanism is within the normal operation range, and the printing mechanism continues to print the job according to the product printing data; if the difference or ratio between the Δm' and the Δm0 exceeds the set variation range, the printing job is paused, and an alarm prompt is issued for manual intervention to check the printing mechanism.

[0019] Preferably, the automatic adjustment method can be to clean the printing mechanism by using the ink drop cleaning method, or to clean the printing mechanism by using the positive pressure ink cleaning method.

[0020] As an extension of the present technical solution, the 3D printing device ink ejection amount real-time monitoring system and its monitoring method can also be applied to planar inkjet drawing devices and other inkjet printers, such as office printers, copiers, etc.

[0021] The beneficial effects of the technical scheme of the present application are: through the detection of the ink weight of each nozzle in unit time during the printing process, the monitoring of the ink ejection rate of the nozzle during the printing process is realized, and the current 3D printing part ink addition ratio can be indirectly calculated. In addition, by setting the ink storage mechanism on the 3D printing device and comparing the ink weight in the ink storage box before and after the flash ejection, whether the ink ejection amount still meets the set change range of the printing needs after the printing mechanism works for a period of time is monitored, so that the real-time monitoring of the ink ejection amount of the printing mechanism is realized. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the case that the nozzle corresponds to the ink storage box one by one;

[0023] Figure 2 is a schematic diagram of the case that several nozzles correspond to one ink storage box;

[0024] Figure 3 is a schematic diagram of the printing mechanism nozzle;

[0025] Figure 4 is a schematic diagram of the real-time monitoring method flow;

[0026] Among them, 1-printing mechanism; 101-nozzle; 2-ink storage box; 3-weight detection unit; 4-mounting platform; 5-horizontal detection unit; 6-data acquisition device; 7-upper computer. DETAILED DESCRIPTION

[0027] In order to more clearly illustrate the technical scheme of the present application, the technical scheme of the content of the application is described in detail in combination with the drawings. Obviously, the following description is some typical embodiments of the present application, and other solutions can be obtained by those skilled in the art without creative labor.

[0028] In order to solve the real-time monitoring accuracy of the ink ejection amount of the 3D printing device during the printing process, and improve the convenience of the real-time monitoring place, a 3D printing device with a flash ejection function is adopted, which means that the printing mechanism moves to a specific position, such as the ink storage mechanism position described in the present application, after printing a set number of layers or a set working time, so that all nozzles eject ink according to the set ink ejection frequency and time length, and the ink is stored in the ink storage mechanism corresponding to the nozzle. In this embodiment, in order to facilitate the control of the printing mechanism, the ink ejection frequency of the flash ejection is the same as the ink ejection frequency of the printing operation of the printing mechanism.

[0029] As shown in Figure 1 , it is the implementation mode of the present application that the nozzle corresponds to the ink storage box one by one.

[0030] In the present embodiment, the 3D printing device uses an ink ejection amount real-time monitoring system, which comprises a printing mechanism 1, an ink storage box 2, a weight detection unit 3, a mounting platform 4, a data acquisition device 6 and an upper computer 7. The printing mechanism 1 and the mounting platform 4 are both arranged on the frame of the 3D printing device, and the mounting platform 4 is arranged below the printing mechanism 1. The weight detection unit 3 is arranged on the surface of the mounting platform 4 facing the printing mechanism 1, and the ink storage box 2 is arranged on the weight detection unit 3. The weight detection unit 3 is used to detect the weight of the ink storage box 2. The data acquisition device 6 is used to acquire various types of data of the working site of the 3D printing device, such as the data of the weight detection unit 3 in the present embodiment, and transmit the acquired data of the weight detection unit 3 to the upper computer 7. The upper computer 7 analyzes various types of acquired data of the working site, and sends relevant instructions to the 3D printing device. The upper computer 7 is electrically connected with the data acquisition device 6 and the weight detection unit 3 to realize the transmission of information, instructions or data among each other. For example, in the present embodiment, the upper computer 7 is communicatively connected with the data acquisition device 6 and the weight detection unit 3 to realize the sending of instructions and / or the transmission of data among each other.

[0031] As a supplement to the present embodiment, one ink storage box 2 corresponds to one weight detection unit 3, that is, the ink storage box 2 corresponds to the weight detection unit 3 one by one, and one weight detection unit 3 only weighs the weight of one ink storage box 2. The weight difference or ratio of the two times of weighing can be used to determine whether the ink ejection amount of the subsequent flash ejection meets the set change range. In this case, the calculation of the ink ejection amount is simple, the ink ejection amount change monitoring accuracy is high, but more ink storage boxes 2 and weight detection units 3 are consumed.

[0032] As another supplement to the present embodiment, several ink storage boxes 2 share one weight detection unit 2, that is, one weight detection unit 3 weighs the weight of several ink storage boxes 2. In this case, the number of weight detection units 3 is saved, but the calculation amount of the upper computer is increased, and the accuracy of ink ejection amount change monitoring is also reduced, because the weight of single ink ejection amount is increased, so that the change of small amount and single ink ejection cannot be well monitored.

[0033] As a supplement to the present embodiment, the ink storage box 2 is directly placed on the weight detection unit 3 to realize the purpose and effect of weighing the weight of the ink storage box 2 by the weight detection unit 3. Or, the ink storage box 2 is clamped or magnetically connected on the weight detection unit 3 to realize the fixed connection between the two, so as to avoid the problem of inaccurate weighing caused by the instability of the ink storage box 2.

[0034] As another supplement of the present embodiment, the distance between the upper edge of the ink storage box 2 arranged on the weight detection unit 3 and the printing mechanism 1 is equal to the distance between the printing mechanism 1 and the powder laying surface; that is, the upper edge of the ink storage box 2 entrance is in the same horizontal plane as the powder laying surface; or, the upper edge of the ink storage box 2 entrance is in the same horizontal plane as the printing work surface of the printing mechanism 1 of the 3D printing equipment. The position of the ink storage box 2 is thus arranged, so that after the printing mechanism 1 prints the set number of layers or time, it does not need to adjust the position in the height direction, but directly travels to the ink storage mechanism to perform the flash spraying operation, realizing the continuity of the printing operation and the monitoring operation of the printing mechanism 1, and improving the operation efficiency of the 3D printing equipment.

[0035] As another supplement of the present embodiment, in order to accurately weigh the ink increase or decrease rate before and after the flash spraying of the ink storage box 2, the accuracy of the weight detection unit 3 is not less than 1% of the ink weight change rate; at the same time, the maximum range of the weight detection unit 3 is the ink weight of the full ink storage box 2, which should be able to accommodate all the ink sprayed during the printing of the largest product by the 3D printing equipment, that is, according to the set flash spraying frequency and time, the ink amount sprayed during the whole printing process of the product.

[0036] As another supplement of the present embodiment, the installation platform 4 is also provided with a level detection unit 5, which is used to detect the levelness of the installation platform 4, so as to ensure that the weight detection unit 3 can be in a horizontal state, thereby ensuring the accuracy of the ink weight measurement.

[0037] As a supplement of the present embodiment, the printing mechanism 1 is composed of a plurality of independent nozzles 101 arranged in a matrix, each independent nozzle 101 corresponding to an ink storage box 2, that is, the nozzle 101 and the ink storage box 2 are in a one-to-one correspondence, or each ink storage box 2 is used to store the ink sprayed by the nozzle 101, and each ink storage box 2 is used to store or accommodate the ink sprayed by the corresponding nozzle 101 for a set number of times during the whole product printing process. In this case, the nozzle 101 and the ink storage box 2 are in one-to-one correspondence, which realizes the accurate detection of the amount of ink sprayed by each independent nozzle 101, and realizes the real-time and accurate monitoring of the ink spraying amount of the 3D printing equipment.

[0038] The real-time monitoring method of the ink spraying amount of the 3D printing equipment in the present embodiment comprises,

[0039] 1) setting the number of layers of the printing mechanism 1 performing flash spraying in the corresponding control module of the upper computer 7;

[0040] 2) the printing mechanism 1 performs a printing operation according to printing data of a product to be printed;

[0041] 3) if the number of layers printed by the printing mechanism 1 reaches a set number of layers, the printing mechanism 1 travels to the ink storage mechanism;

[0042] 4) the printing mechanism 1 performs a flash operation according to a set flash frequency and duration;

[0043] 5) the weight detection unit 3 detects the weight of the ink storage box 2 after the current flash;

[0044] 6) it is determined whether the ink ejection amount of the current flash is within a set variation range, if yes, the printing mechanism 1 continues to perform a printing operation; if no, the ink ejection amount of the printing mechanism 1 is abnormal, and the ink ejection amount of the printing mechanism 1 needs to be automatically adjusted;

[0045] 7) after the automatic adjustment, the printing mechanism 1 performs a flash operation again, and it is determined again whether the ink ejection amount of the flash after the automatic adjustment is within the set variation range, if yes, the printing mechanism 1 continues to perform a printing operation; if no, a stop command is issued and an alarm is given.

[0046] As another supplement of the present embodiment, the determination step of whether the ink ejection amount is normal specifically includes:

[0047] 1) the data acquisition device 6 uploads the weight m2 of the ink storage box 2 after the current flash weighed by the weight detection unit 3 to the upper computer 7;

[0048] 2) the upper computer 7 obtains the ink ejection amount Δm of the current flash by comparing the weight m2 of the ink storage box 2 after the current flash with the weight m1 of the ink storage box 2 before the current flash;

[0049] 3) the ink ejection amount Δm of the current flash is compared with a set ink ejection amount Δm0, if the difference or ratio of the two is within a set variation range, the ink ejection amount of the printing mechanism 1 is normal, and a printing operation can be continued; if the difference or ratio of the two exceeds the set variation range, it indicates that the ink ejection amount of the corresponding ink ejection head 101 of the printing mechanism 1 is abnormal, and the ink ejection amount of the printing mechanism 1 needs to be automatically adjusted.

[0050] After performing the automatic adjustment once, the determination step of whether the ink ejection amount is normal specifically includes:

[0051] 1) the data acquisition device 6 uploads the weight m2 of the ink storage box 2 after the current flash weighed by the weight detection unit 3 to the upper computer 7;

[0052] 2) The host computer 7 calculates the difference between the weight m3 of the ink collection box 2 after the current flash spray after automatic adjustment and the weight m1 of the ink collection box 2 before the current flash spray before automatic adjustment, and obtains the ink spray volume △m′ of the current flash spray.

[0053] 3) Compare the ink volume Δm′ of the current flash print after automatic adjustment with the set ink volume Δm0. If the difference or ratio between the two is within the set range, the ink volume of the printing mechanism 1 is normal and the printing job can continue. If the difference or ratio exceeds the set range, a stop command is issued and an alarm is triggered, and manual intervention is required to check the printing mechanism 1.

[0054] As a supplement to this implementation, the automatic adjustment method can be to clean the printing mechanism using either the drip ink cleaning method or the positive pressure ink cleaning method.

[0055] In the case where each printhead 101 corresponds to one ink collection box 2, △m, △m′, and △m0 are all the ink ejection volume of a single flash of a single printhead 101. By comparing the ink ejection volume of a single printhead 101 in a single flash, the ink ejection volume of the printing mechanism 1 throughout the entire printing process is accurately monitored, thereby achieving precise control of the ink ejection volume during the printing process. This improves the stability of the product printing quality and avoids the waste of production costs and high quality costs caused by the failure to detect abnormal ink ejection of the printhead 101 in a timely manner.

[0056] As another supplement to this implementation, the real-time ink jet monitoring system of the 3D printing equipment can also achieve precise control of the amount of ink used in the product to be printed, avoid ink waste, and effectively control printing costs. Specifically, it calculates the ink addition ratio ф of the product to be printed, Ф=∑△m / (v*t*b*h*ρ), where v is the printing speed of the printing mechanism 1, t is the duration of the flash spray operation, b is the printing width of the printhead 101, h is the thickness of the powder layer, ρ is the density of the product to be printed, and ∑△m is the total amount of ink jetted by a single printhead during the entire printing process.

[0057] like Figure 2 The diagram illustrates an implementation of the present invention where multiple printheads share a single ink collection container. In this implementation, only technical features differing from the one-to-one correspondence scenario are described to avoid excessive repetition.

[0058] For the case of single ink ejection amount is large or the control of ink ejection amount is not very accurate, several ink ejection heads 101 can share one ink storage box 2. This not only solves the problem of high cost of the real-time monitoring system, but also solves the problem of high difficulty of manufacturing. At this time, the △m, △m' and △m0 are the sum of ink ejection amounts of several ink ejection heads 101 in the corresponding state.

[0059] As an extension of the technical solution, the 3D printing device ink ejection amount real-time monitoring system and the monitoring method thereof can also be applied to planar inkjet drawing devices and other inkjet printers, such as office printers, copiers, etc.

[0060] The above examples are only a description of a typical application of the technical solution of the present application, and reasonable expansion can be made on the basis of reasonable and without creative labor.

Claims

1. A system for real-time monitoring of ink ejection volume of a 3D printing device, comprising a printing mechanism, characterized in that, Also include ink storage mechanism, data acquisition device and host computer; The printing mechanism is arranged on the 3D printing equipment to realize inkjet printing of the 3D printing equipment; The ink storage mechanism is arranged on the 3D printing equipment and below the printing mechanism in the monitoring state; The data acquisition device is arranged on the ink storage mechanism and has a communication connection with the ink storage mechanism to transmit the data of the ink storage mechanism to the host computer; The host computer is in communication connection with the data acquisition device, the printing mechanism and the ink storage mechanism to receive or issue relevant information or instructions; The ink storage mechanism includes an ink storage box, a weight detection unit and a mounting platform, the mounting platform is arranged on the 3D printing equipment, the weight detection unit is arranged on the mounting platform, and the ink storage box is arranged on the weight detection unit, and the weight detection unit is used to weigh the weight of the ink storage box; The distance from the upper edge of the ink storage box inlet on the weight detection unit to the printing mechanism is equal to the distance from the printing mechanism to the powder laying surface.

2. The system for real-time monitoring of ink ejection volume of a 3D printing device of claim 1, wherein, Each ink storage box is below a weight detection unit to weigh the weight of each ink storage box.

3. The system for real-time monitoring of ink ejection volume of a 3D printing device of claim 1, wherein, Several ink storage boxes share one weight detection unit.

4. The system for real-time monitoring of ink ejection volume of a 3D printing device of claim 1, wherein, The mounting platform is also provided with a level detection unit to detect the levelness of the mounting platform.

5. The system for real-time monitoring of ink ejection volume of a 3D printing device of claim 1, wherein, The printing mechanism is composed of several independent nozzles arranged in a matrix, and each independent nozzle corresponds to an ink storage box, or several independent nozzles share one ink storage box.

6. A method for real-time monitoring of ink ejection amount of a 3D printing device, using the system for real-time monitoring of ink ejection amount of a 3D printing device according to claim 5, characterized in that, The monitoring method comprises: Setting the number of layers of the printing mechanism to perform flash printing in the corresponding control module of the host computer; The printing mechanism performs printing operation according to the printing data of the product to be printed; If the number of layers of the printing mechanism reaches the set number of layers, the printing mechanism moves to the ink storage mechanism; The printing mechanism performs flash printing operation according to the set flash printing frequency and time length; The weight detection unit detects the weight of the ink storage box after the current flash printing; Determine whether the ink ejection amount of the current flash printing is within the set variation range, if yes, the printing mechanism continues to perform printing operation, if not, the ink ejection amount of the printing mechanism is abnormal, and the ink ejection amount of the printing mechanism needs to be automatically adjusted; After automatic adjustment, the printing mechanism performs flash printing operation again, and determines whether the ink ejection amount of the flash printing after automatic adjustment is within the set variation range, if yes, the printing mechanism continues to perform printing operation, if not, a stop command is issued and an alarm is given.

7. The method of claim 6, wherein the method further comprises: determining the amount of ink ejected from the nozzle based on the determined distance between the nozzle and the substrate. The specific content of determining whether the ink ejection amount of the current flash printing is within the set variation range comprises: The data acquisition device uploads the weight m2 of the ink storage box after the current flash printing weighed by the weight detection unit to the host computer; The host computer obtains the ink ejection amount△m of the current flash printing by comparing the weight m2 of the ink storage box after the current flash printing with the weight m1 of the ink storage box before the current flash printing. The ink jet amount of the current flash jet is compared with the set ink jet amount Δm0. If the difference or ratio of the two is within the set variation range, the ink jet amount of the printing mechanism is normal, and the printing job can be continued. If the difference or ratio of the two exceeds the set variation range, the ink jet amount of the nozzle corresponding to the ink storage box is abnormal, and the ink jet amount of the printing mechanism needs to be automatically adjusted.

8. The method of claim 7, wherein the method further comprises: determining the amount of ink ejected from the nozzle based on the determined distance between the nozzle and the substrate. The ink addition ratio f can also be calculated, where f = ∑△m / (v*t*b*h*ρ), v is the printing speed of the printing mechanism, t is the length of the flash jet job, b is the printing width of the nozzle 101, h is the thickness of the powder layer, p is the density of the product to be printed, and ∑△m is the total weight of the ink jet of all nozzles in the current flash jet job.

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