Title of Invention: Powder Mixing System and Powder Mixing Method
Technical field
[0001]
　The present invention relates to a powder mixing system and a powder mixing method for mixing multiple types of powder.
Background technology
[0002]
　For example, in the fields of powder metallurgy, pharmaceutical formulations, food, etc., powders, which are aggregates of particulate solids, are used as mixtures of various types of materials, compositions, and particle sizes. . The mixed state of a mixture composed of multiple types of powders affects the final quality of the product manufactured using the mixture. should reach a sufficiently homogeneous mixture. Therefore, as an index for judging whether a homogeneous mixed state has been reached, the degree of mixing, which expresses the mixed state numerically, is measured, and quality optimization and quality control of the final product are performed based on this degree of mixing. .
[0003]
　For example, in the abstract column of Patent Document 1, in order to "present a stable evaluation index for the uniformity in the mixed state of the mixture", "a uniformity evaluation device for a mixture in which a plurality of types of substances are mixed, an input unit for inputting input information indicating the physical quantity of each of the plurality of types of substances constituting the mixture or the number of each of the plurality of types of substances; and based on the input information, the plurality of types of substances used for mixing. and a second mixing ratio of each substance constituting an inspection region that is part of a mixture in which the plurality of substances are in a mixed state, the first a calculator that calculates entropy indicating the degree of difference between the mixture ratio and the second mixture ratio; and an output unit that outputs the calculation result calculated by the calculator.
prior art documents
patent literature
[0004]
Patent Document 1: JP-A-2018-72158
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0005]
　In the uniformity evaluation apparatus disclosed in Patent Document 1, part of the powder in the mixing process is taken out from the mixing container, and then the image of the taken out powder is measured to determine the quantity and mass of the powder. Since it is measured, it takes time to complete the mixing, and there is a problem that the productivity of the final product is low.
[0006]
　SUMMARY OF THE INVENTION An object of the present invention is to provide a powder mixing system and a powder mixing method in which the time required for the completion of mixing is shortened and the productivity of the final product is enhanced.
Means to solve problems
[0007]
　In order to achieve the above object, the powder mixing system of the present invention comprises a mixing container having a rotating shaft for mixing a plurality of types of powder, and a rotating machine for rotating the mixing container via the rotating shaft. , an image capturing device for capturing an image of the powder during the mixing process, and a computer, wherein the mixing container has a window for capturing the image of the powder, and the computer includes , the mixing container has a function of detecting that it is in a predetermined position, the imaging device acquires the powder image through the window of the mixing container at the predetermined position, and the computer acquires The mixing state of the powder is estimated based on the obtained powder image.
[0008]
　Further, the powder mixing method of the present invention comprises a mixing container having a rotating shaft for mixing a plurality of types of powder, a rotating machine for rotating the mixing container via the rotating shaft, and a powder image in the mixing process. and a computer, wherein when the computer detects that the mixing container being rotated by the rotating machine is at a predetermined position, mixing The image capturing device acquires a digital RGB color image of the powder in the process, the computer extracts an image of the specific powder from a plurality of types of powder, and uses the position information of the extracted specific powder. and calculating the mixing degree based on the existence probability of the specific powder in the mixed powder whole image, and ending the mixing when the mixing degree satisfies a predetermined condition.
Effect of the invention
[0009]
　According to the present invention, by directly estimating the mixed state of powders in the mixing process on the spot, the overall mixing time can be shortened, and the productivity of the final product is improved. A mixing method can be provided.
Brief description of the drawing
[0010]
1 is a cross-sectional view of a powder mixing system according to Example 1 of the present invention; FIG.
2 is a cross-sectional view when the mixing container in the powder mixing system according to Example 1 of the present invention is rotated; FIG.
3 is a cross-sectional view showing communication between an image capturing device and a computer in the powder mixing system according to Example 1 of the present invention; FIG.
4 is a flowchart showing a powder mixing method; FIG.
[Fig. 5] An image of the mixed powder photographed by an image photographing device.
[Fig. 6] A graph showing the degree of mixing of copper powder with respect to mixing time.
[Fig. 7] A graph showing the degree of mixing of graphite powder with respect to mixing time.
8 is a cross-sectional view of a powder mixing system according to Example 2 of the present invention; FIG.
9 is a cross-sectional view showing communication between an image capturing device and a computer in a powder mixing system according to Example 2 of the present invention; FIG.
MODE FOR CARRYING OUT THE INVENTION
[0011]
　An embodiment of the present invention will be described below with reference to FIGS. 1 to 9. FIG.
Example 1
[0012]
FIG. 1 is a cross-sectional view of a powder mixing system according to this embodiment.
[0013]
　The powder mixing system of this embodiment has a rotating shaft 2, a mixing container 1 for mixing a plurality of types of powders 7, and a rotating machine (not shown) for rotating the mixing container 1 via the rotating shaft 2. , an image capturing device 5 for acquiring powder images during the mixing process, and a computer 8 .
[0014]
　The mixing container 1 has a substantially V-shape, and has a powder discharge port 4 formed at the bottom thereof, a powder inlet 3 formed at the upper end of one of the two branches, and a powder inlet 3 formed at the upper end of the other branch. An observation window and window frame 6 are attached to the upper end. The window frame 6 supports the outer periphery of an observation window for taking an image of the powder 7 and is detachable from the mixing container 1 . Further, the powder inlet 3 is detachably provided with a lid for opening and closing the inlet. Therefore, in the powder mixing system of this embodiment, the lid at the powder input port 3 on one end side and the window frame 6 on the other end side can be exchanged with each other. For example, if the work space on one end side is limited and it is difficult to charge the powder 7 from the one end side, an observation window is arranged at the upper end of the one end side and the powder charge is placed at the upper end of the other end side. A mouth 3 can also be arranged. In addition, since the powder input port 3 and the observation window are provided at the bifurcated upper end where a relatively wide opening can be formed, the powder can be easily input and a wide range of observation is possible.
[0015]
　When the powder 7 is introduced from the powder inlet 3, the mixing container 1 is kept stationary with the powder inlet 3 positioned upward as shown in FIG. After the powder 7 is put in and the lid is closed, the mixing container 1 is rotated by the rotating machine, so that the powder discharge port 4 is positioned upward or downward, and the upside down reversal is repeated. Meanwhile, the powder 7 in the mixing container 1 is gradually mixed. An imaging device 5 can be fixed to the window frame 6, and when the imaging device 5 is fixed, the mixed powder in the mixing container 1 is photographed through the observation window.
[0016]
　Here, when the inside of the mixing container 1 is photographed from above with the imaging device 5 positioned upward as shown in FIG. Not only are the particles separated from each other, but the vicinity of the upper surface is covered with the lightest particles of the powder 7, so that the measurement accuracy of the mixed state is lowered. Therefore, as shown in FIG. 2, by photographing the inside of the mixing container 1 when the image photographing device 5 is positioned downward, it is possible to photograph the inside of the mixing container 1 from a position close to the powder 7, thereby improving the measurement accuracy.
[0017]
　Further, as shown in FIG. 3, the image capturing device 5 can communicate with the computer 8 by transmission. Since the image capturing device 5 of this embodiment rotates together with the mixing container 1 in order to make the whole powder mixing system compact, wireless communication is required. The computer 8 has a function of detecting that the mixing container 1 is at a predetermined position, more specifically, that the imaging device 5 is positioned below. As for the timing of photographing by the image photographing device 5, the image may be photographed at the moment when the image photographing device 5 passes under the mixing container 1 while the mixing container 1 is being rotated. The rotation of the container 1 may be stopped before photographing. Further, the computer 8 estimates the mixed state of the powder 7 based on the powder image received from the image capturing device 5 .
[0018]
　Next, a method of mixing the powder 7 will be described with reference to FIG. FIG. 4 is a flow chart showing a method of mixing the powder 7. As shown in FIG.
[0019]
　First, a predetermined weight of powder 7 made of a plurality of kinds of raw materials is weighed, and the powder 7 is charged into the mixing container 1 through the powder inlet 3 . When mixing is started in step S100, the mixing container 1 rotates. Next, when the computer 8 detects in step S101 that the mixing container 1 being rotated by the rotating machine is at a predetermined position, the imaging device 5 captures a digital RGB color image of the powder 7 in the mixing process through the observation window. to get through. The acquired RGB color image information is sent to the computer 8 by wireless transmission, and the computer 8 performs image processing for extracting an image of a specific powder from a plurality of types of powder. Specifically, first, in step S102, the RGB (red, green, blue) color information of the entire image of the mixed powder is converted to HSV (hue, saturation, brightness) color information or CIE-L*a*b* color information. converted into information. Next, by extracting HSV color information and the like specific to the specific powder 7 in step S103, the pixel position of the specific powder 7 in the entire image is extracted (step S104). After that, the whole image is divided into an arbitrary number (step S105), and the mixing degree is calculated using the number of pixels of the specific powder 7 existing in one divided image (step S106). Note that the accuracy of estimating the mixed state improves as the number of divisions increases.
[0020]
　Here, the mixing degree of the powder 7 based on the existence probability of the specific powder 7 in the whole image is calculated by the following formula.
[0021]
[Number 1]

[0022]
Note that S indicates the mixing degree of the powder 7, C the number of pixels related to the specific powder 7 in the whole image, M the number of divisions of the whole image, and Pj,c the existence probability for j and C.
[0023]
　As the mixing progresses, the randomness of the powder 7 in the overall image increases, and the degree of mixing gradually increases, approaching unity. However, the upper limit of the degree of mixing, that is, the degree of mixing in a homogeneous mixed state that can actually occur is less than one.
[0024]
　In step S107, it is determined whether or not the degree of mixing satisfies a predetermined condition. As a specific determination method in step S107, for example, when the difference from the degree of mixing calculated last time becomes equal to or less than a predetermined value, it is determined that the mixing state has stabilized and that the mixing has ended.
[0025]
　As described above, in this embodiment, even if there is no initial information such as the proportion of the powder 7 before mixing, only the image information of the powder 7 in the mixing process can be used to determine the powder 7. can be estimated. In addition, even if part of the powder 7 in the mixing process is not taken out from the mixing container 1, it can be directly estimated on the spot using the image capturing device 5, so the overall mixing time can be shortened and the powder is completed after mixing. The production efficiency of the final product to be manufactured is improved.
[0026]
　Next, the results of actual mixing using the powder mixing system of this embodiment will be described. Here, an example of calculating the degree of mixing by photographing the mixed state of iron powder-based mixed powder used for powder metallurgy applications of iron alloy materials will be shown. As the iron powder-based mixed powder, a mixed powder composed of four kinds of powders of atomized iron powder, electrolytic copper powder, graphite, and zinc stearate was used. The atomized iron powder is grayish, the electrolytic copper powder is reddish, the graphite is blackish, and the zinc stearate is whiteish.
[0027]
　First, 97% iron, 1% electrolytic copper powder, 1% graphite powder, and 1% zinc stearate are weighed and put into the V-shaped mixing vessel 1 in the powder mixing system to start mixing. Then, an image of the mixed powder in the mixing process was taken with respect to the mixing time.
[0028]
　FIG. 5 shows an image of the mixed powder photographed 0.03 minutes after the start of mixing by the image photographing device 5 with a pixel size of 3.5 μm. As shown in FIG. 5, at a mixing time of 0.03 minutes, the four mixed powders are in a mixed state with segregation.
[0029]
　First, the calculation of the mixing degree focusing on the electrolytic copper powder will be described. The computer 8 extracts the image of the copper powder by extracting the reddish color information peculiar to the copper powder from the entire image converted into the color information such as HSV, and mixes the copper powder. Calculate degrees. FIG. 6 is a graph showing the degree of mixing of copper powder with respect to mixing time. As shown in FIG. 6, the degree of mixing increases depending on the mixing time, and the mixing process leading to saturation of the degree of mixing can be determined.
[0030]
　Next, the calculation of the degree of mixture focusing on graphite powder will be described. Calculator 8 extracts the image of graphite powder by extracting color information with saturated luminance from the entire image converted into color information such as HSV, and calculates the degree of mixture of graphite powder. FIG. 7 is a graph showing the degree of mixing of graphite powder with respect to mixing time. Here, the graphite powder is pulverized into fine particles during the mixing process and adheres to the surfaces of the iron powder and the copper powder. Therefore, as the mixing progresses, the bright areas decrease. Therefore, with regard to graphite powder, it is possible to calculate the degree of mixture even without hue information.
Example 2
[0031]
FIG. 8 is a cross-sectional view of the powder mixing system according to this embodiment. In the powder mixing system of this embodiment, the window frame 16 is replaceable with the cover of the powder outlet. Further, the image capturing device 15 of this embodiment is arranged on a straight line that intersects the rotary shaft 12 perpendicularly and passes through the powder outlet. As described above, in this embodiment, since an image can be taken at the center of the bottom of the mixing container 1 where the powder outlet is located, the accuracy of estimating the mixed state is improved. Further, unlike the first embodiment, the imaging device 15 of the present embodiment does not rotate integrally with the mixing container 1, so that it can communicate with the computer 18 by wire transmission as shown in FIG. However, it is of course possible to communicate with the computer 18 by wireless transmission.
[0032]
　In the powder mixing system of this embodiment, the inside of the mixing container 11 is photographed when the window frame 16 is positioned facing the imaging device 15, that is, when the window frame 16 is positioned vertically downward. In addition, powder inlets 13 are formed at both of the two-forked upper ends. According to this embodiment as well, the mixed state can be estimated simply by photographing the image of the powder 7 while mixing without removing the powder 7 from the mixing container 11 .
[0033]
　In addition, the present invention is not limited to the first and second embodiments described above, and includes various modifications. The first and second embodiments described above have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described above. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.
Code explanation
[0034]
DESCRIPTION OF SYMBOLS 1, 11... Mixing container, 2, 12... Rotating shaft, 3, 13... Powder inlet, 4, 14... Powder outlet, 5, 15... Image photographing device, 6, 16... Window frame, 7... Powder body, 8, 18... calculator
The scope of the claims
[Claim 1]
　A mixing container having a rotating shaft for mixing a plurality of types of powder, a rotating machine for rotating the mixing container via the rotating shaft, an image capturing device for acquiring an image of the powder during the mixing process, a computer, wherein the mixing container has
　a window for photographing the powder image, the
　computer has a function of detecting that the mixing container is at a predetermined position,
　At the predetermined position, the image capturing device acquires the powder image through the window of the mixing container, and the
　computer estimates the mixing state of the powder based on the acquired powder image. A powder mixing system characterized by:
[Claim 2]
　2. The powder mixing system according to claim 1,
　wherein the window frame including the window of the mixing container has a shape replaceable with a lid of a powder inlet provided in the mixing container, and the
　imaging device . A powder mixing system characterized in that it can be fixed to the window frame and can communicate with the computer by wireless transmission.
[Claim 3]
　2. The powder mixing system according to claim 1,
　wherein the window frame including the window of the mixing container has a shape that is replaceable with a lid of a powder discharge port provided in the mixing container, and the
　rotating shaft and the A powder mixing system, wherein the imaging device is arranged on a straight line that intersects perpendicularly and passes through the powder outlet.
[Claim 4]
　4. The powder mixing system according to claim 3,
　wherein said image capturing device is capable of communicating with said computer by wire transmission.
[Claim 5]
　4. The powder mixing system according to claim 3,
　wherein said image capturing device can communicate with said computer by wireless transmission.
[Claim 6]
　A mixing container having a rotating shaft for mixing a plurality of types of powder, a rotating machine for rotating the mixing container via the rotating shaft, an image capturing device for acquiring an image of the powder during the mixing process, a computer,
　When the computer detects that the mixing container being rotated by the rotating machine is in a predetermined position, a digital RGB color image of the powder in the mixing process is generated . Acquired by the image capturing device, the
　computer extracts an image of the specific powder from a plurality of types of powders, and uses the extracted positional information of the specific powder to determine the specific powder in the mixed powder whole image. calculating a mixing degree based on the existence probability of the powder, and ending the mixing when the mixing degree satisfies a predetermined condition.
[Claim 7]
　7. The powder mixing method according to claim 6,
　wherein the computer converts the RGB color information of the mixed powder whole image into HSV color information or CIE-L*a*b* color information, and converts the HSV color information or Based on the CIE-L*a*b* color information, extract the pixel position of the specific powder in the mixed powder whole image, divide the mixed powder whole image, and calculating the degree of mixing using the number of pixels of the specific powder present in the powder mixing method, and ending the mixing when a difference from the previously calculated degree of mixing becomes equal to or less than a predetermined value.