Patent Application
20240033828
The present invention relates to an additive manufacturing apparatus, a multi-tasking apparatus, a method for controlling the additive manufacturing apparatus, and a computer-readable storage medium storing a control program for the additive manufacturing apparatus.
U.S. Pat. No. 7,045,738 describes an additive manufacturing apparatus that detects the flow rate of powder using an optical sensor. To calibrate the accuracy of the optical sensor, a weigher is placed below a nozzle, and the weigher is removed after calibration work.
According to one aspect of the present invention, an additive manufacturing apparatus includes a powder feeder, a head, a first flow passage, a flow passage switching valve, a reservoir tank, a second flow passage, a first sensor, and a second sensor. The powder feeder is configured to feed powder using a carrier gas. The head is configured to discharge the powder. The first flow passage connects the powder feeder and the head. The flow passage switching valve is provided in the first flow passage. The reservoir tank is configured to receive the powder fed from the powder feeder. The second flow passage connects the flow passage switching valve to the reservoir tank. The first sensor is provided in the first flow passage between the flow passage switching valve and the head to detect a first flow rate of the powder flowing to the head. The second sensor is provided in the second flow passage to detect a second flow rate of the powder flowing to the reservoir tank. The flow passage switching valve is configured to take a first position and a second position alternatively. The powder feeder is connected to the head via the first flow passage in the first position to supply the powder to the head. The powder feeder is connected to the reservoir tank via the second flow passage in the second position to supply the powder to the reservoir tank.
According to another aspect of the present invention, a multi-tasking apparatus includes the above-described additive manufacturing apparatus and a cutting device configured to perform a cutting process.
According to further aspect of the present invention, a method for controlling an additive manufacturing apparatus includes supplying powder from a powder feeder that is operated under a predetermined operating condition to a first flow passage, which connects the powder feeder to a head, to discharge the powder from the head. The powder flowing through the first flow passage is detected using a first sensor. A first flow rate of the powder flowing to the head is calculated based on an output of the first sensor. A flow passage through which the powder is to be fed from the powder feeder is switched from the first flow passage to a second flow passage, which connects the powder feeder to a reservoir tank. The powder is fed from the powder feeder that is operated under the predetermined operating condition to the reservoir tank through the second flow passage. The powder flowing through the second flow passage is detected using a second sensor. A second flow rate of the powder flowing to the reservoir tank is calculated based on an output of the second sensor.
According to further aspect of the present invention, a computer-readable storage medium storing a control program for causing an additive manufacturing apparatus to execute a process. The process includes operating a powder feeder under a predetermined operating condition to supply powder to a first flow passage, which connects the powder feeder to a head, to discharge the powder from the head. The process includes acquiring an output of the first sensor that detects the powder flowing through the first flow passage. The process includes calculating a first flow rate of the powder flowing to the head based on the output of the first sensor. The process includes switching a flow passage through which the powder is to be fed from the powder feeder from the first flow passage to a second flow passage, which connects the powder feeder to a reservoir tank. The process includes operating the powder feeder under the predetermined operating condition to feed the powder to the second flow passage. The process includes acquiring an output of a second sensor that detects the powder flowing through the second flow passage. The process includes calculating a second flow rate of the powder flowing to the reservoir tank based on the output of the second sensor.
A more complete appreciation of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The present invention will now be described in detail with reference to the drawings illustrating embodiments of the present invention. Like reference numerals designate corresponding or approximately identical elements throughout the drawings.
The first movement mechanism 107 can move the cutting device 106 in an X-axis direction and a Y-axis direction in addition to a Z-axis direction in
The second movement mechanism 108 can move the additive manufacturing apparatus 10 in the X-axis direction and the Y-axis direction in addition to the Z-axis direction in
The additive manufacturing apparatus 10 discharges the powder through the head 12 as described above. The first flow passage 15 is part of the transporting mechanism 14 described above and connects the powder feeder 11 to the head 12. The powder is supplied from the powder feeder 11 to the head 12 through the first flow passage 15. The flow passage switching valve 16 is located in the middle of the first flow passage 15. The reservoir tank 17 is configured to receive the powder fed from the powder feeder 11. The additive manufacturing apparatus 10 may further include a measurement instrument SC1 that is capable of measuring the amount of powder that accumulates in the reservoir tank 17. For example, the measurement instrument SC1 is a weight scale that measures the weight of the powder that accumulates in the reservoir tank 17.
The second flow passage 18 connects the flow passage switching valve 16 to the reservoir tank 17. The powder flows from the powder feeder 11 to the reservoir tank 17 through the second flow passage 18. The flow passage switching valve 16 is capable of alternatively selecting whether to supply the powder from the powder feeder 11 to the head 12 or to the reservoir tank 17. It is to be noted that
The first sensor 13 is located in the first flow passage 15 between the flow passage switching valve 16 and the head 12. The first sensor 13 is configured to detect a first flow rate of the powder flowing to the head 12. The second sensor 19 is located in the second flow passage 18 and is configured to detect a second flow rate of the powder flowing to the reservoir tank 17. The first sensor 13 and the second sensor 19 are preferably optical sensors. It is to be noted, however, that the first sensor 13 and the second sensor 19 may be other kinds of sensors that can measure the flow rate of the powder. For example, the first sensor 13 and the second sensor 19 may be an ultrasonic flow meter, an impeller flow meter, or other flow meters. When the first sensor 13 and the second sensor 19 are optical sensors, transmissive windows are preferably provided at a position in the first flow passage 15 where the first sensor 13 is located and a position in the second flow passage 18 where the second sensor 19 is located. The light from the optical sensors passes through the transmissive windows. It is to be noted that the first flow passage 15 and the second flow passage 18 may be pipes made of material that allows the light to pass through. In this case, the section of the pipe corresponding to the position in the first flow passage 15 where the first sensor 13 is located and the section of the pipe corresponding to the position in the second flow passage 18 where the second sensor 19 is located are equivalent to the transmissive windows described above.
As illustrated in
The third transmissive window W3 is configured to allow a light beam LR1 inside the first flow passage 15 to be transmitted to the outside of the first flow passage 15. The fourth transmissive window W4 is configured to allow a light beam LR2 inside the second flow passage 18 to be transmitted to the outside of the second flow passage 18. The third transmissive window W3 and the fourth transmissive window W4 may be anything as long as the light beam LR1 and the light beam LR2 are allowed to pass through. It is to be noted, however, that the third transmissive window W3 preferably has a high transmittance for the light beam LR1. The fourth transmissive window W4 preferably has a high transmittance for the light beam LR2. The first transmissive window W1 is preferably made of approximately the same material as the third transmissive window W3. The first transmissive window W1 preferably has approximately the same thickness as the third transmissive window W3. The second transmissive window W2 is preferably made of approximately the same material as the fourth transmissive window W4. The second transmissive window W2 preferably has approximately the same thickness as the fourth transmissive window W4. Furthermore, the first transmissive window W1, the second transmissive window W2, the third transmissive window W3, and the fourth transmissive window W4 are preferably made of the same material and have a high transmittance for the light beam LO1, the light beam LO2, the light beam LR1, and the light beam LR2. For example, the first transmissive window W1, the second transmissive window W2, the third transmissive window W3, and the fourth transmissive window W4 are preferably made of material that has a transmittance of 90% or more for the light beam having the wavelength corresponding to the light beam LO1, the light beam LO2, the light beam LR1, and the light beam LR2. Furthermore, the first transmissive window W1, the second transmissive window W2, the third transmissive window W3, and the fourth transmissive window W4 preferably have approximately the same thickness and are preferably thin. Thus, the first flow passage 15 and the second flow passage 18 may be formed of light transmissive pipes of the same product. In this case, the section of the light transmissive pipe corresponding to the position in the first flow passage 15 where the first sensor 13 is located and the section of the light transmissive pipe corresponding to the position in the second flow passage 18 where the second sensor 19 is located are equivalent to the first transmissive window W1, the second transmissive window W2, the third transmissive window W3, and the fourth transmissive window W4.
Next, the measurement principle of the optical sensors will be described. As illustrated in
Thus, the relationship between the output of the first sensor 13 and the first flow rate of the powder flowing through the first flow passage 15 can be described using a mathematical model. In the following description, the mathematical model is referred to as a first mathematical model MD1. Similarly, the relationship between the output of the second sensor 19 and the second flow rate of the powder flowing through the second flow passage 18 can be described using a mathematical model. In the following description, the mathematical model is referred to as a second mathematical model MD2. More strictly, the first mathematical model MD1 is the model that describes the relationship between the value obtained by filtering the output of the first sensor 13 and the first flow rate of the powder flowing through the first flow passage 15. The second mathematical model MD2 is the model that describes a relationship between the value obtained by filtering the output of the second sensor 19 and the second flow rate of the powder flowing through the second flow passage 18.
Specifically, the processor 31 is configured to execute the control program PG to calculate the first flow rate from the output of the first sensor 13 based on the first mathematical model MD1 and calculate the second flow rate from the output of the second sensor 19 based on the second mathematical model MD2. That is, the method for controlling the additive manufacturing apparatus 10 includes calculating the first flow rate from the output of the first sensor 13 based on the first mathematical model MD1, which describes the relationship between the output of the first sensor 13 and the first flow rate of the powder, and calculating the second flow rate from the output of the second sensor 19 based on the second mathematical model MD2, which describes the relationship between the output of the second sensor 19 and the second flow rate of the powder. The control program PG causes the processor 31 to execute processes of calculating the first flow rate from the output of the first sensor 13 based on the first mathematical model MD1, which describes the relationship between the output of the first sensor 13 and the first flow rate of the powder, and calculating the second flow rate from the output of the second sensor 19 based on the second mathematical model MD2, which describes the relationship between the output of the second sensor 19 and the second flow rate of the powder.
Furthermore, the processor 31 is configured to determine whether there is an abnormality in the additive manufacturing apparatus 10 by comparing the output of the first sensor 13 when the powder is supplied from the powder feeder 11, which is operated under a predetermined operating condition, to the first flow passage 15 with the output of the second sensor 19 when the powder is supplied from the powder feeder 11, which is operated under the predetermined operating condition, to the second flow passage 18 through the execution of the control program PG. That is, the method for controlling the additive manufacturing apparatus 10 includes determining whether there is an abnormality in the additive manufacturing apparatus 10 by comparing the output of the first sensor 13 when the powder is supplied from the powder feeder 11, which is operated under the predetermined operating condition, to the first flow passage 15 with the output of the second sensor 19 when the powder is supplied from the powder feeder 11, which is operated under the predetermined operating condition, to the second flow passage 18. The control program PG causes the processor 31 to execute a process of determining whether there is an abnormality in the additive manufacturing apparatus 10 by comparing the output of the first sensor 13 when the powder is supplied from the powder feeder 11, which is operated under the predetermined operating condition, to the first flow passage 15 with the output of the second sensor 19 when the powder is supplied from the powder feeder 11, which is operated under the predetermined operating condition, to the second flow passage 18.
The controller CL further includes, for example, a first input/output interface 33, a second input/output interface 34, a bus 35, and a non-illustrated power supply. The first input/output interface 33 is connected to the notification device 103. The first input/output interface 33 is, for example, a video output interface or a sound output interface. The second input/output interface 34 is connected to the first sensor 13, the second sensor 19, the measurement instrument SC1, and an additional measurement instrument SC2, which will be discussed below, and receives output signals from these devices. The second input/output interface 34 is, for example, a serial interface such as USB or a parallel interface such as RS-232C or SCSI. The bus 35 connects the processor 31, the memory 32, the first input/output interface 33, and the second input/output interface 34 with each other. The bus 35 transmits output signals from the first sensor 13, the second sensor 19, the measurement instrument SC1, and the additional measurement instrument SC2 to the processor 31, transmits signals between the processor 31 and the memory 32, and transmits signals output from the processor 31 to the first input/output interface 33. The signals output from the processor 31 indicate, for example, the first flow rate, the second flow rate, and an abnormality in the additive manufacturing apparatus 10. In
Next, the first mathematical model MID and the second mathematical model MD2 will be described. As described above, experience shows that when the signals from the light receiver 132 and the light receiver 192 are filtered through, for example, a movement-average filter, the processed signals generally change linearly with respect to the flow rate of the powder flowing through the first flow passage 15 and the flow rate of the powder flowing through the second flow passage 18. Thus, the first mathematical model MD1 representing the relationship between the first flow rate F1 of the powder flowing through the first flow passage 15 and a signal S1 obtained by filtering the output of the light receiver 132 is expressed by a mathematical expression S1=K1×F1+A1. Similarly, the second mathematical model MD2 representing the relationship between the second flow rate F2 of the powder flowing through the second flow passage 18 and a signal S2 obtained by filtering the output of the light receiver 192 is expressed by a mathematical expression S2=K2×F2+A2. It is to be noted that the first mathematical model MID and the second mathematical model MD2 do not necessarily have to be expressed by such a linear function. Additionally, when the first sensor 13 and the second sensor 19 are the same products, A1≈A2. Furthermore, experience shows that A1≈A2≈0.
The first mathematical model MD1 is generated as follows. The flow passage switching valve 16 is in a first position such that the powder from the powder feeder 11 flows through the first flow passage 15. As illustrated in
The second mathematical model MD2 is generated as follows. The flow passage switching valve 16 is in a second position such that the powder from the powder feeder 11 flows through the second flow passage 18. At the same time as when the powder is discharged to the reservoir tank 17 at two or more flow rates by changing the rotational speed of the rotatable measurement disk of the powder feeder 11, the output of the second sensor 19 at that time and the changes over time in the weight on the measurement instrument SC1 are measured. Based on the value obtained by filtering the output of the second sensor 19 and the corresponding changes over time in the weight on the measurement instrument SC1, K2 and A2 can be estimated by maximum likelihood estimation such as a least-square method. That is, the mathematical model MD2 is generated based on the correspondence relationship between the changes in the amount in the reservoir tank 17 per unit time and the output of the second sensor 19 corresponding to the changes in the reservoir tank 17. That is, the method for controlling the additive manufacturing apparatus 10 includes measuring the amount of powder accumulated in the reservoir tank 17 and generating the second mathematical model MD2 based on the correspondence relationship between the changes in the amount in the reservoir tank 17 per unit time and the output of the second sensor 19 corresponding to the changes in the reservoir tank 17. The control program PG causes the processor 31 to execute processes of acquiring a measured value of the amount of powder accumulated in the reservoir tank 17 and generating the second mathematical model MD2 based on the correspondence relationship between the changes in the amount in the reservoir tank 17 per unit time and the output of the second sensor 19 corresponding to the changes in the reservoir tank 17. It is to be noted that, for a periodic calibration process, which will be discussed below, the processor 31 preferably obtains a ratio β between K2 and K1, that is, β=K1/K2 and stores the ratio β in the memory 32. The difference between K1 and K2 occurs due to the individual differences between the first sensor 13 and the second sensor 19 or the influence on the discharge by connecting the head 12 to the first flow passage 15. However, in broad terms, the ratio β does not change after long use of the additive manufacturing apparatus 10. On this premise, the additive manufacturing apparatus 10 performs the following processes.
During normal operation of the additive manufacturing apparatus 10, the flow passage switching valve 16 is set so that the powder from the powder feeder 11 flows through the first flow passage 15, and the processor 31 obtains the first flow rate of the powder flowing to the head 12 by substituting the detected value of the first sensor 13 into the first mathematical model MD1. The obtained first flow rate is output to the notification device 103 and displayed on, for example, a display of the operation panel 102. The periodic calibration process illustrated in
Next, at step S13, the processor 31 executes an updating process of acquiring the output of the second sensor 19 that has detected the powder flowing through the second flow passage 18 after the flow passage switching valve 16 has switched the flow passage through which the powder is to be fed from the powder feeder 11 to the second flow passage 18, and updating the first mathematical model MD1 using the output, the first mathematical model MD1, and the second mathematical model MD2. That is, the method for controlling the additive manufacturing apparatus 10 includes the updating process of acquiring the output of the second sensor 19 that has detected the powder flowing through the second flow passage 18 after the flow passage switching valve 16 has switched the flow passage through which the powder is to be fed from the powder feeder 11 to the second flow passage 18, and updating the first mathematical model MID using the output, the first mathematical model MID1, and the second mathematical model MD2. The control program PG causes the processor 31 to execute the updating process of acquiring the output of the second sensor 19 that has detected the powder flowing through the second flow passage 18 after the flow passage switching valve 16 has switched the flow passage through which the powder is to be fed from the powder feeder 11 to the second flow passage 18, and updating the first mathematical model MD1 using the output, the first mathematical model MID1, and the second mathematical model MD2.
At step S13, specifically, at step S131, the processor 31 acquires the output of the second sensor 19 that has detected the powder flowing through the second flow passage 18 after the flow passage switching valve 16 has switched the flow passage through which the powder is to be fed from the powder feeder 11 to the second flow passage 18. At the same time, the processor 31 also acquires the changes over time in the weight on the measurement instrument SC1 mounted on the reservoir tank 17 and updates the parameter of the second mathematical model MD2 using the acquired changes over time as the flow rate of the powder. That is, the method for controlling the additive manufacturing apparatus 10 includes acquiring the output of the second sensor 19 that has detected the powder flowing through the second flow passage 18 after the flow passage switching valve 16 has switched the flow passage through which the powder is to be fed from the powder feeder 11 to the second flow passage 18. Furthermore, the controlling method also includes simultaneously acquiring the changes over time in the weight on the measurement instrument SC1 mounted on the reservoir tank 17 and updating the parameter of the second mathematical model MD2. The control program PG causes the processor 31 to execute the process of acquiring the output of the second sensor 19 that has detected the powder flowing through the second flow passage 18 after the flow passage switching valve 16 has switched the flow passage through which the powder is to be fed from the powder feeder 11 to the second flow passage 18. Furthermore, the control program PG causes the processor 31 to execute the processes of also simultaneously acquiring the changes over time in the weight on the measurement instrument SC1 mounted on the reservoir tank 17 and updating the parameter of the second mathematical model MD2. It is to be noted that the parameter of the second mathematical model MD2 is the above-mentioned parameter K2. In the following description, the updated parameter K2 is referred to as K2′.
At step S132, the processor 31 updates the parameter of the first mathematical model MD1 based on the correspondence relationship between the first mathematical model MD1 and the second mathematical model MD2. More specifically, the processor 31 updates the parameter K1 of the first mathematical model MD1 using the above-described ratio β. That is, the method for controlling the additive manufacturing apparatus 10 includes updating the parameter of the first mathematical model MD1 based on the correspondence relationship between the first mathematical model MD1 and the second mathematical model MD2. More specifically, the method for controlling the additive manufacturing apparatus 10 includes updating the parameter K1 of the first mathematical model MD1 using the above-described ratio β. The control program PG causes the processor 31 to execute the process of updating the parameter of the first mathematical model MD1 based on the correspondence relationship between the first mathematical model MD1 and the second mathematical model MD2. More specifically, the control program PG causes the processor 31 to execute the process of updating the parameter K1 of the first mathematical model MD1 using the above-described ratio β. It is to be noted that when the updated K1 is referred to as K1′, K1′=β×K2′.
Since the above-described updating process is executed at periodic points in time, the processor 31 is configured to repeat the updating process at a predetermined cycle. The method for controlling the additive manufacturing apparatus 10 repeats the updating process at a predetermined cycle. The control program PG causes the processor 31 to execute the process of repeating the updating process at a predetermined cycle. The above updating process allows the first mathematical model MD1 to be updated without removing the workpiece W from the additive manufacturing apparatus 10.
The processor 31 is capable of determining an abnormality in the additive manufacturing apparatus 10 by comparing the output of the first sensor 13 with the output of the second sensor 19 when the powder feeder 11 is operated under the same operating condition. The operating condition of the power feeder 11 is defined by the rotational speed of the rotatable measurement disk and the flow rate of the carrier gas. It is to be noted that, in terms of determining the location of the abnormality in the powder feeder 11, the pipe cross-sectional shape of the first flow passage 15 and the pipe cross-sectional shape of the second flow passage 18 are preferably approximately the same. This is because when the operating condition of the powder feeder 11 is the same, the first flow rate of the powder flowing through the first flow passage 15 and the second flow rate of the powder flowing through the second flow passage 18 are approximately equal. Although a variety of methods may be used to determine whether there is an abnormality, two abnormality determining methods will be described below as examples.
At step S15, the processor 31 switches the flow passage through which the powder is to be fed to the first flow passage 15 and acquires the output of the first sensor 13 when the powder feeder 11 is operated under the operating condition that is the same as the operating condition that achieves the flow rate of the powder measured by the measurement instrument SC1 at step S131. That is, the method for controlling the additive manufacturing apparatus 10 includes switching the flow passage through which the powder is to be fed to the first flow passage 15 and acquiring the output of the first sensor 13 when the powder feeder 11 is operated under the operating condition that is the same as the operating condition that achieves the flow rate of the powder measured by the measurement instrument SC1 at step S131. The control program PG causes the processor 31 to execute the processes of switching the flow passage through which the powder is to be fed to the first flow passage 15 and acquiring the output of the first sensor 13 when the powder feeder 11 is operated under the operating condition that is the same as the operating condition that achieves the flow rate of the powder measured by the measurement instrument SC1 at step S131.
At step S16, the processor 31 executes a determining process of determining whether there is an abnormality in the additive manufacturing apparatus 10 by comparing the predicted output with the output of the first sensor 13 that has detected the powder flowing through the first flow passage 15 after the flow passage switching valve 16 has switched the flow passage through which the powder is to be fed from the powder feeder 11 to the first flow passage 15. The method for controlling the additive manufacturing apparatus 10 includes the determining process of determining whether there is an abnormality in the additive manufacturing apparatus 10 by comparing the predicted output with the output of the first sensor 13 that has detected the powder flowing through the first flow passage 15 after the flow passage switching valve 16 has switched the flow passage through which the powder is to be fed from the powder feeder 11 to the first flow passage 15. The control program PG causes the processor 31 to execute the determining process of determining whether there is an abnormality in the additive manufacturing apparatus 10 by comparing the predicted output with the output of the first sensor 13 that has detected the powder flowing through the first flow passage 15 after the flow passage switching valve 16 has switched the flow passage through which the powder is to be fed from the powder feeder 11 to the first flow passage 15. For example, when an absolute value of the difference between the output of the first sensor 13 and the predicted output is greater than a predetermined threshold value, it is determined that an abnormality has occurred in the additive manufacturing apparatus 10.
In response to determining that no abnormality has occurred in the additive manufacturing apparatus 10 (NO at step S16), the operation of the additive manufacturing apparatus 10 is continued at step S17, and the process returns to step S11. That is, the processor 31 is configured to repeat the determining process at a predetermined cycle. The method for controlling the additive manufacturing apparatus 10 repeats the determining process at a predetermined cycle. The control program PG causes the processor 31 to execute the process of repeating the determining process at a predetermined cycle.
In response to determining that an abnormality has occurred in the additive manufacturing apparatus 10 (YES at step S16), at step S18, the processor 31 controls the notification device 103 to raise an alarm or brings the additive manufacturing apparatus 10 to an emergency stop. That is, the method for controlling the additive manufacturing apparatus 10 includes, in response to determining that there is an abnormality, controlling the notification device 103 for providing information to a user to raise an alarm or bringing the additive manufacturing apparatus 10 to an emergency stop. The control program PG causes, in response to determining that there is an abnormality, the processor 31 to execute the process of controlling the notification device 103 for providing information to a user to raise an alarm or bringing the additive manufacturing apparatus 10 to an emergency stop.
With the above processes, it can be periodically determined whether the additive manufacturing apparatus 10 is operating properly using a spare time such as when the workpiece W is replaced without stopping the production of the workpiece W by the additive manufacturing apparatus 10. Besides the above-mentioned spare time, the determination may be made in every step of the additive manufacturing.
At step S22, the processor 31 acquires the output of the first sensor 13 that detects the powder flowing through the first flow passage 15. That is, the method for controlling the additive manufacturing apparatus 10 includes detecting the powder flowing through the first flow passage 15 using the first sensor 13. The control program PG causes the processor 31 to execute the process of acquiring the output of the first sensor 13 that detects the powder flowing through the first flow passage 15. At step S23, the processor 31 calculates the first flow rate of the powder flowing to the head 12 based on the output of the first sensor 13. That is, the method for controlling the additive manufacturing apparatus 10 includes calculating the first flow rate of the powder flowing to the head 12 based on the output of the first sensor 13. The control program PG causes the processor 31 to execute the process of calculating the first flow rate of the powder flowing to the head 12 based on the output of the first sensor 13.
At step S24, the processor 31 determines whether the output of the first sensor 13 has deviated from a normal fluctuation range while the powder is supplied to the head 12 from the powder feeder 11 operated under a regular operating condition. That is, the method for controlling the additive manufacturing apparatus 10 includes determining whether the output of the first sensor 13 has deviated from the normal fluctuation range while the powder is supplied to the head 12 from the powder feeder 11 operated under a regular operating condition. The control program PG causes the processor 31 to execute the process of determining whether the output of the first sensor 13 has deviated from the normal fluctuation range while the powder is supplied to the head 12 from the powder feeder 11 operated under a regular operating condition. The normal fluctuation range refers to a range in which the output of the first sensor 13 can be deemed normal from the first mathematical model MD1 and the operating condition of the powder feeder 11. The normal fluctuation range is obtained at the same time as when the first mathematical model MID is generated and is stored in the memory 32. For example, the powder feeder 11 is activated multiple times under the same operating condition when the first mathematical model MD1 is generated, and the normal fluctuation range may be set so that a value obtained by adding an offset to the maximum output of the first sensor 13 serves as the upper limit and a value obtained by subtracting an offset from the minimum output of the first sensor 13 serves as the lower limit. When the output of the first sensor 13 is within the normal fluctuation range (NO at step S24), the process returns to step S21.
When the output of the first sensor 13 deviates from the normal fluctuation range (YES at step S24), at step S25, the processor 31 switches the flow passage through which the powder is to be fed from the powder feeder 11 from the first flow passage 15 to the second flow passage 18, which connects the powder feeder 11 to the reservoir tank 17. That is, the method for controlling the additive manufacturing apparatus 10 includes switching the flow passage through which the powder is to be fed from the powder feeder 11 from the first flow passage 15 to the second flow passage 18, which connects the powder feeder 11 to the reservoir tank 17. The control program PG causes the processor 31 to execute the process of switching the flow passage through which the powder is to be fed from the powder feeder 11 from the first flow passage 15 to the second flow passage 18, which connects the powder feeder 11 to the reservoir tank 17.
At step S26, the processor 31 causes the powder feeder 11 that is set to the predetermined operating condition to feed the powder to the second flow passage 18. That is, the method for controlling the additive manufacturing apparatus 10 includes feeding the powder from the powder feeder 11 that is set to the predetermined operating condition to the reservoir tank 17 through the second flow passage 18. The control program PG causes the processor 31 to execute the process of making the powder feeder 11 that is set to the predetermined operating condition to feed the powder to the second flow passage 18. It is to be noted that the operating condition of the powder feeder 11 at step S21 is the same as the operating condition of the powder feeder 11 at step S26.
At step S27, the processor 31 acquires the output of the second sensor 19 that detects the powder flowing through the second flow passage 18. That is, the method for controlling the additive manufacturing apparatus 10 includes detecting the powder flowing through the second flow passage 18 using the second sensor 19. The control program PG causes the processor 31 to execute the process of acquiring the output of the second sensor 19 that detects the powder flowing through the second flow passage 18. At step S28, the processor 31 calculates the second flow rate of the powder flowing to the reservoir tank 17 based on the output of the second sensor 19. That is, the method for controlling the additive manufacturing apparatus 10 includes calculating the second flow rate of the powder flowing to the reservoir tank 17 based on the output of the second sensor 19. The control program PG causes the processor 31 to execute the process of calculating the second flow rate of the powder flowing to the reservoir tank 17 based on the output of the second sensor 19.
At step S29, the processor 31 determines whether an abnormality is in the powder feeder 11 or in at least one of the first flow passage 15 and the first sensor 13 based on the output of the first sensor 13 and the output of the second sensor 19. That is, the method for controlling the additive manufacturing apparatus 10 includes determining whether an abnormality is in the powder feeder 11 or in at least one of the units including the first flow passage 15 and the first sensor 13 based on the output of the first sensor 13 and the output of the second sensor 19. The control program PG causes the processor 31 to execute the process of determining whether an abnormality is in the powder feeder 11 or in at least one of the units including the first flow passage 15 and the first sensor 13 based on the output of the first sensor 13 and the output of the second sensor 19.
When the absolute value of the difference between the first flow rate and the second flow rate is greater than the predetermined threshold value (YES at step S291), at step S292, the processor 31 determines that an abnormality has occurred in at least one of the first sensor 13 and the first flow passage 15. That is, the method for controlling the additive manufacturing apparatus 10 includes determining that an abnormality has occurred in at least one of the first sensor 13 and the first flow passage 15 when the absolute value of the difference between the first flow rate and the second flow rate is greater than the predetermined threshold value. The control program PG causes the processor 31 to execute the process of determining that an abnormality has occurred in at least one of the first sensor 13 and the first flow passage 15 when the absolute value of the difference between the first flow rate and the second flow rate is greater than the predetermined threshold value.
When the absolute value of the difference between the first flow rate and the second flow rate is less than or equal to the predetermined threshold value (NO at step S291), at step S293, the processor 31 determines that an abnormality has occurred in the powder feeder 11. That is, the method for controlling the additive manufacturing apparatus 10 includes determining that an abnormality has occurred in the powder feeder 11 when the absolute value of the difference between the first flow rate and the second flow rate is less than or equal to the predetermined threshold value. The control program PG causes the processor 31 to execute the process of determining that an abnormality has occurred in the powder feeder 11 when the absolute value of the difference between the first flow rate and the second flow rate is less than or equal to the predetermined threshold value.
The additive manufacturing apparatus 10, the multi-tasking apparatus 100, the method for controlling the additive manufacturing apparatus 10, and the control program PG for the additive manufacturing apparatus 10 according to the present embodiment switch from the first flow passage 15, which connects the powder feeder 11 to the head 12, to the second flow passage 18, which connects the powder feeder 11 to the reservoir tank 17, and calculate the first flow rate of the powder flowing to the head 12 and the second flow rate of the powder flowing to the reservoir tank 17. Thus, even if an abnormality occurs in the additive manufacturing apparatus 10, the cause of the abnormality can be investigated without removing the workpiece W from the additive manufacturing apparatus 10. Additionally, in the additive manufacturing apparatus 10, the powder feeder 11 can be checked for proper operation or the first sensor 13 can be calibrated while the workpiece W is not machined such as during transferring.
The abnormality determining method according to the present embodiment is not intended as limiting and may be other methods as long as the abnormality determining method utilizes the configuration of the additive manufacturing apparatus 10 described in the embodiment. Additionally, the measurement instrument SC1 and the additional measurement instrument SC2 are not limited to a weight scale and may be one that measures the volume of the powder. In this case, the flow rate of the powder may be the volume of the powder that flowed through each of the first flow passage 15 and the second flow passage 18 per unit time.
When the method that expresses the periodic calibration process and the abnormality determining process illustrated in the present embodiment in a more generic concept is referred to as the method for controlling the additive manufacturing apparatus 10, the method for controlling the additive manufacturing apparatus 10 includes at least steps S21 to S23 and steps S25 to S27 of
The control program PG described above does not necessarily have to be the one stored in the memory 32 integrated in the controller CL but may be the one that is stored in a storage medium removable from the controller CL and readable by the controller CL including, for example, disks such as a floppy disk, an optical disk, a CD-ROM, or a magnetic disk, an SD card, a USB memory, or an external hard disk.
As used herein, the term “comprise” and its variations are intended to mean open-ended terms, not excluding any other elements and/or components that are not recited herein. The same applies to the terms “include”, “have”, and their variations.
As used herein, a component suffixed with a term such as “member”, “portion”, “part”, “element”, “body”, and “structure” is intended to mean that there is a single such component or a plurality of such components.
As used herein, ordinal terms such as “first” and “second” are merely used for distinguishing purposes and there is no other intention (such as to connote a particular order) in using ordinal terms. For example, the mere use of “first element” does not connote the existence of “second element”; otherwise, the mere use of “second element” does not connote the existence of “first element”.
As used herein, approximating language such as “approximately”, “about”, and “substantially” may be applied to modify any quantitative representation that could permissibly vary without a significant change in the final result obtained. All of the quantitative representations recited in the present application shall be construed to be modified by approximating language such as “approximately”, “about”, and “substantially”.
As used herein, the phrase “at least one of A and B” is intended to be interpreted as “only A”, “only B”, or “both A and B”.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present disclosure may be practiced otherwise than as specifically described herein.
The present application is a continuation application of International Application No. PCT/JP2020/041584, filed Nov. 6, 2020. The contents of this application are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2020/041584 | Nov 2020 | US |
| Child | 18307811 | US |
