Powder supply system

Abstract

To feed alloy powder of predetermined weight to a vibration bowl feeder from a plurality of take-out ports to a pressing machine.SOLUTION: A powder feed system according to the present disclosure comprises: a vibration bowl feeder comprising a spiral conveyance truck for conveying powder via vibration, and a plurality of discharge openings provided on an outer peripheral surface; a plurality of powder weighing devices allocated to the plurality of discharge openings, respectively; a plurality of gate opening / closing devices that branch the powder conveyed by the vibration bowl feeder from above the conveyance truck and feed the powder to the respective powder weighing devices corresponding thereto from the plurality of gate opening / closing devices; and a control device for controlling the plurality of gate opening / closing devices and the plurality of powder weighing devices. The powder is fed to the plurality of powder weighing devices from the plurality of discharge openings, and the powder is fed to a pressing machine from the plurality of powder weighing devices, with a gate opening degree of each gate opening / closing device controlled by the control device based on weight of the powder measured by each powder weighing device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to a powder feeding system. [Background technology]

[0002] RTB type sintered magnets (R is a rare earth element and must contain at least one selected from the group consisting of Nd, Pr, and Ce, T is at least one transition metal and must contain Fe, and B is boron) are 2 Fe 14 It is composed of a main phase of a compound having a B-type crystal structure, a grain boundary phase located at the grain boundaries of this main phase, and a compound phase formed by the influence of trace additive elements and impurities. RTB-based sintered magnets have a high residual magnetic flux density B r and high coercive force H cJ It is known as the most highly efficient permanent magnet.

[0003] For this reason, RTB sintered magnets are used in a variety of motors in the automotive sector, including electric vehicles (EVs, HVs, PHVs), renewable energy sectors such as wind power generation, home appliances, and industrial sectors. RTB sintered magnets are an essential material for making these motors smaller, lighter, more efficient, and more energy-efficient (improved energy efficiency). RTB sintered magnets are also used in the drive motors of electric vehicles, and the replacement of internal combustion engine vehicles with electric vehicles contributes to preventing global warming by reducing greenhouse gases such as carbon dioxide (reducing fuel and exhaust gases). In this way, RTB sintered magnets are making a significant contribution to the realization of a clean energy society.

[0004] RTB sintered magnets are manufactured through processes such as preparing powder (alloy powder), press-molding the alloy powder in a press to produce a powder compact, and sintering the powder compact.

[0005] US Patent No. 5,399,633 describes a vibratory bowl feeder that feeds alloy powder to a press. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] China Patent Application Publication No. 106743183 Summary of the Invention [Problem to be solved by the invention]

[0007] In order to supply a predetermined weight of alloy powder into the die cavity of the press, it is necessary to accurately extract powder having a target weight from the alloy powder supply source. If the weight of the alloy powder varies, the density of the compact powder produced in the pressing process may become non-uniform, which may deteriorate the properties of the sintered magnet.

[0008] Patent Document 1 describes a technique for removing powder from a single removal port of a vibratory bowl feeder.

[0009] An embodiment of the present disclosure provides a powder feeding system in which a vibratory bowl feeder is provided with multiple outlets, and a predetermined weight of powder can be fed to a press from each outlet. [Means for solving the problem]

[0010] In an exemplary embodiment, the powder supply system of the present disclosure includes a vibratory bowl feeder having a spiral transport track that transports powder by vibration and a plurality of discharge openings provided on an outer peripheral surface, a plurality of powder measuring devices each assigned to the plurality of discharge openings, a plurality of gate opening / closing devices that branch the powder transported by the vibratory bowl feeder from the transport track and supply it to a corresponding powder measuring device from the plurality of discharge openings, and a control device that controls the plurality of gate opening / closing devices and the plurality of powder measuring devices, and the control device controls the gate opening degree of each of the plurality of gate opening / closing devices based on the weight of the powder measured by each of the plurality of powder measuring devices.

[0011] In one embodiment, each of the multiple gate opening and closing devices is a gate movable member that opens and closes the discharge opening, and in a gate open state, moves the powder moving in a region of a predetermined width on the transport track radially outward of the transport track to drop from the discharge opening into the powder measuring device, and in a gate closed state, moves the powder moving on the transport track in a circumferential direction of the transport track, and an actuator that drives the gate movable member to adjust the gate opening degree determined by the width. The control device controls the gate opening degree of each of the multiple gate opening and closing devices based on the weight of the powder measured by each of the multiple powder measuring devices, so that the powder is supplied from the multiple discharge openings to the multiple powder measuring devices, and the powder is supplied from the multiple powder measuring devices to the press machine.

[0012] In one embodiment, in a gate open state, the control device drives the corresponding gate movable member to reduce the gate opening degree as the weight of the powder measured by each of the plurality of powder measuring devices increases.

[0013] In one embodiment, the control device gradually reduces the gate opening as the weight of the powder increases.

[0014] In one embodiment, the control device discharges the powder in each powder measuring device from the powder measuring device when the weight of the powder measured by each powder measuring device reaches a target weight.

[0015] In one embodiment, the control device measures a weighing time until the weight of the powder measured by the powder measuring device reaches a target weight, and changes the gate opening based on the difference between the target weighing time and the measured weighing time.

[0016] In one embodiment, when the difference is within a predetermined range, the control device maintains the current gate opening as the gate opening, and when the difference is not within the predetermined range and predetermined conditions are satisfied, the control device adopts a value obtained by multiplying the current gate opening by a correction value as the gate opening.

[0017] In one embodiment, the predetermined condition is that the number of weighings in which the difference is not within the predetermined range reaches a set value.

[0018] In one embodiment, the correction value has a different value depending on the difference.

[0019] In one embodiment, the correction value has a first value greater than 1 when the difference is in a first range higher than the predetermined range, a second value greater than the first value when the difference is in a second range higher than the first range, a third value less than 1 when the difference is in a third range lower than the predetermined range, and a fourth value less than the third value when the difference is in a fourth range lower than the third range. Effect of the Invention

[0020] According to an embodiment of the present disclosure, it is possible to supply powder from multiple discharge openings (outlets) of a vibratory bowl feeder to multiple powder measuring devices, and to supply a predetermined weight of powder from the multiple powder measuring devices to a press machine. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a plan view that diagrammatically illustrates a portion of an example configuration of a powder supplying system 100 according to the present embodiment. [Diagram 2] FIG. 2 is a schematic side view of the powder feeding system 100 of FIG. 1 taken along the negative Z axis. [Diagram 3] FIG. 3 is a schematic side view of the powder feeding system 100 of FIG. 1 taken along the negative X-axis. [Figure 4]FIG. 4 is a schematic diagram showing how the conveying track 2 of the vibratory bowl feeder 10 forms a spiral slope within the bowl. [Diagram 5] FIG. 5 is a schematic plan view showing the gate opening and closing device 30 in more detail. [Figure 6] FIG. 6 is a plan view showing the position and orientation of the gate movable member 32 in the gate closed state. [Figure 7] FIG. 7 is a plan view showing the position and orientation of the gate movable member 32 in the gate open state. [Figure 8] FIG. 8 is a graph showing a schematic relationship between the gate opening degree and the weight of powder measured by each powder measuring device 20. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a powder feeding system according to the present disclosure;

[0023] First, a configuration example of a powder supply system according to an embodiment of the present disclosure will be described with reference to Figs. 1 to 3. For reference, mutually orthogonal X, Y, and Z axes are shown in the figures. Fig. 1 is a plan view showing a schematic part of a configuration example of a powder supply system 100 according to the present embodiment. Fig. 2 is a schematic side view of the powder supply system 100 of Fig. 1 as viewed from the negative direction of the Z axis, and Fig. 3 is a schematic side view of the powder supply system 100 of Fig. 1 as viewed from the negative direction of the X axis.

[0024] The powder feeding system 100 in this embodiment includes a vibratory bowl feeder 10, a plurality of powder metering devices 20, a plurality of gate opening and closing devices 30, and a controller 40. In the illustrated example, the vibratory bowl feeder 10, the powder metering devices 20, and the gate opening and closing devices 30 are disposed within a housing 12.

[0025] The vibrating bowl feeder 10 has a spiral conveying track (vibrating rail) 2 that conveys powder by vibration, and a plurality of discharge openings 6 provided on the outer circumferential surface 4. More specifically, the vibrating bowl feeder 10 has a cylindrical container (bowl) 11 having a bottom for storing powder, and a vibrator device 7 (see FIG. 3) that vibrates the bowl 11. The shape of the bowl 11 is not limited to a cylindrical shape, and may have a stepped shape so that the upper part expands. The bottom of the bowl 11 has a conical shape with a raised center. Therefore, the powder (see FIG. 3) supplied from above to the bowl 11 tends to spread along the incline to the outer circumferential side of the bowl 11 without concentrating in the center of the bottom. The conveying track 2 forms a slope that draws two spirals along the inner wall surface of the bowl 11 from the outer circumferential side area at the bottom of the bowl 11. The conveying track 2 is vibrated by the vibrator device 7, and the powder on the conveying track 2 is gradually moved in the ascending direction of the slope. 1 indicates the circumferential direction of the conveying track 2. In this embodiment, the powder supplied to the center of the vibrating bowl feeder 10 can move on the conveying track 2 in a clockwise direction along the "circumferential direction" indicated by the arrow P. During this movement, if all the gate opening / closing devices 30 arranged in the vicinity of each discharge opening 6 are closed (gate closed state), the alloy moving on the conveying track 2 falls from the upper end of the conveying track 2 to the bottom of the bowl 11 and circulates.

[0026] In this embodiment, six discharge openings 6 are provided on the outer peripheral surface 4 of one vibratory bowl feeder 10. Six powder measuring devices 20 are assigned to the six discharge openings 6, respectively. Each of the six discharge openings 6 is provided with a gate opening / closing device 30. The numbers of the discharge openings 6, the powder measuring devices 20, and the gate opening / closing devices 30 are not limited to six, and may be two to five, or seven or more.

[0027] FIG. 4 is a diagram showing a state in which the conveying track 2 of the vibratory bowl feeder 10 forms a spiral slope inside the bowl 11. In FIG. 4, the dotted line shows the position of the upper surface of the conveying track 2. The position of the lower end of the discharge opening 6 is aligned with the position of the upper surface of the conveying track 2. The number of revolutions of the spiral is not limited to two. The track width and inclination angle (slope angle) of the conveying track 2, and the amplitude and frequency of the applied vibration are arbitrary.

[0028] In this embodiment, the gate opening / closing device 30 serves to divert the powder transported by the vibrating bowl feeder 10 from the transport track 2, and supplies the powder from the multiple discharge openings 6 to the corresponding powder measuring devices 20. The size of the discharge openings 6, i.e., the circumferential length of the discharge openings, is not particularly limited and may be any size.

[0029] As shown in FIG. 1, each of the gate opening / closing devices 30 includes a gate movable member 32 and an actuator 34. The gate movable member 32 is a member that opens and closes the discharge opening 6. The gate movable member 32 can be made of a metal material such as stainless steel. In the illustrated example, the gate movable member 32 is a thin plate (having a thickness of, for example, 5 to 15 mm) having a triangular tip portion, and the direction of the tip portion can be freely adjusted by an actuator 34 such as a motor. In the gate open state, the gate movable member 32 moves the powder moving in a region of a predetermined width W on the transport track 2 to the radial outside of the transport track 2, causing it to drop from the discharge opening 6 to the powder measuring device 20 (FIG. 5). In addition, in the gate closed state, the gate movable member 32 moves the powder moving on the transport track 2 in the circumferential direction (arrow P) of the transport track 2.

[0030] The actuator 34 is configured to drive the gate movable member 32 to adjust the gate opening degree, which is determined by the magnitude of the width W.

[0031] FIG. 5 is a schematic plan view showing the gate opening / closing device 30 in more detail. In FIG. 5, the gate movable member 32 does not close the discharge opening 6, and the gate is in an open state. The gate movable member 32 is supported rotatably around a fulcrum position, and an actuator 34 can change the direction of the gate movable member 32. Of the powder moving on the conveying track 2 in the direction of the arrow A, a portion of the powder moving within the region of width W is guided by one side of the gate movable member 32 and pushed outward in the radial direction of the conveying track 2 to fall. On the other hand, of the powder moving on the conveying track 2 in the direction of the arrow A, a portion of the powder moving in a region radially inward from the region of width W is guided by the other side of the gate movable member 32 and pushed outward in the radial direction of the conveying track 2, but can pass by the side of the gate movable member 32 as it is. As is clear from FIG. 5, the weight of the powder falling from the discharge opening 6 can be controlled by adjusting the width W and adjusting the time of the gate open state.

[0032] Fig. 6 is a plan view showing the position and orientation of the gate movable member 32 in the gate closed state. In the gate closed state, powder moving as indicated by arrow A passes by the side of the discharge opening 6 as indicated by arrow B. Fig. 7 is a plan view showing the position and orientation of the gate movable member 32 in the gate open state. In the gate open state, some of the powder moving as indicated by arrow A is taken out from the discharge opening 6 as indicated by arrow C, so the amount of powder passing by the side of the discharge opening 6 as indicated by arrow B decreases.

[0033] As is clear from FIG. 7, the larger the gate opening is, the more the amount of powder taken out from the discharge opening 6 increases as shown by the arrow C, and the less the amount of powder that passes by the discharge opening 6 and reaches the next discharge opening 6 (not shown in FIG. 7) as shown by the arrow B. For this reason, when multiple discharge openings 6 are provided along one conveying track 2 as in this embodiment, a smaller gate opening is less likely to adversely affect the take-out of powder from the other discharge openings 6. However, if the gate opening is small, it takes a longer time for the weight of the powder to reach the target value, which may reduce mass productivity. In the embodiment of the present disclosure, it is possible to execute control that can take out powder evenly from multiple discharge openings 6 while increasing mass productivity. A specific example of this control will be described later. The opening includes both the angle when the gate is opened from a closed state and the angle when the gate is partially closed from an open state (opening / closing angle).

[0034] In this embodiment, each of the powder measuring devices 20 includes a measuring cup 20a and a small rotating device 20b that supports the measuring cup 20a. The small rotating device 20b has a load cell (weight measuring element) that measures the weight of the powder supplied to the measuring cup 20a. Such a powder measuring device 20 sends the measured value of the weight of the powder supplied to the measuring cup 20a as an electric signal to the control device 40. When the powder is being supplied to the measuring cup 20a from the discharge opening 6 in the gate open state, the measured value of the weight that increases with time can be obtained continuously or periodically and provided to the control device 40. After the weight of the powder supplied to the measuring cup 20a reaches a target value and the gate is changed from the open state to the closed state, the powder measuring device 20 can reverse the up-down direction of the measuring cup 20a by the small rotating device 20b. As a result of this inversion, the powder held in measuring cup 20a can be fed to a die cavity (not shown), an intermediate cup, or a powder filling device via chute 8, the upper end of which widens like a funnel. Therefore, when the die of the press machine has multiple cavities, it is possible to feed the appropriate weight of powder to each cavity from a single vibratory bowl feeder.

[0035] The control device 40 is configured to control the multiple gate opening / closing devices 30 and the multiple powder measuring devices 20. Specifically, the control device 40 is configured to control the gate opening degree of each of the multiple gate opening / closing devices 30 based on the weight of powder measured by each of the multiple powder measuring devices 20. An example of the operation of the control device 40 will be described below. Note that the control devices may be separate for the multiple gate opening / closing devices 30 and the multiple powder measuring devices 20 (there may be one or more control devices).

[0036] In this embodiment, the control device 40 drives the corresponding gate movable member 32 to reduce the gate opening degree as the weight of the powder measured by each of the multiple powder measuring devices 20 increases in the gate open state. In one embodiment, the control device 40 reduces the gate opening degree stepwise as the weight of the powder increases. Then, when the weight of the powder measured by each powder measuring device 20 reaches the target weight, the control device 40 discharges the powder in each powder measuring device 20 from the powder measuring device 20 and drops it, for example, into the chute 8. In this specification, obtaining the target weight of powder with each powder measuring device 20 in this manner is called "weighing". In the process of performing one "weighing", the "weighing" of the powder may be performed multiple times (for example, periodically).

[0037] Hereinafter, the gate opening degrees of the six gate opening / closing devices 30 will be referred to as the "first gate opening degree," the "second gate opening degree," . . . , and the "sixth gate opening degree," respectively.

[0038] FIG. 8 is a graph showing a schematic relationship between the gate opening and the weight of the powder measured by each powder measuring device 20. The vertical axis of the graph is the gate opening, and the horizontal axis is the weight of the powder. In this example, the gate opening is controlled to be gradually decreased at the timing when the weight reaches w1, w2, w3, w4, w5, and w6 (unit: grams). Regarding the first gate opening, the first gate opening is maintained at, for example, 110% of the reference value until the weight of the powder in the measuring cup 20a reaches w1 gram, and is controlled to decrease to 95% of the reference value when the weight reaches w1 gram. The reference value is, for example, a width of W=5 mm. Thereafter, the first gate opening can be changed to, for example, 84%, 70%, 55%, 32%, and 18% at the timing when the weight reaches w2, w3, w4, w5, and w6, respectively. To adjust the weight with high accuracy, it is preferable to be able to finely adjust the gate opening as the measured weight value approaches the target value. In this example, the value obtained by subtracting w6 from the target value is set to 1 gram or less, and w6-w5 can be set to 2 grams or less. Although not shown in FIG. 8, immediately after the gate is changed from the closed state to the open state, the gate opening may be temporarily (for example, for 0.1 seconds) increased to, for example, a maximum value within the movable range in order to, for example, check the gate opening / closing operation or to increase the accuracy of the subsequent operation. The second, ..., and sixth gate openings are also adjusted based on the respective measured weights.

[0039] In this way, the gate opening degrees of the six gate opening / closing devices 30 can be adjusted to different degrees. As described above, the gate opening degree of a certain gate opening / closing device 30 can affect the adjustment of the gate opening degree located downstream of the transport track 2, but according to this embodiment, accurate weighing is possible by each gate opening / closing device 30.

[0040] In this embodiment, the control device 40 measures the weighing time until the weight of the powder measured by the powder measuring device 20 reaches the target weight. Then, the gate opening is changed based on the difference E between the target weighing time Tt and the measured weighing time Tm. The "difference E" here is not limited to "Tm-Tt" but includes ratios such as "Tm / Tt".

[0041] In this embodiment, when the difference E is within a predetermined range (dead band), the control device 40 maintains the current gate opening as the gate opening. When the difference E is not within the predetermined range, if a predetermined condition is satisfied, the control device 40 adopts the current gate opening multiplied by a correction value Q as the gate opening. The predetermined condition is, for example, that the number of measurements in which the difference E is not within the predetermined range reaches a set value (for example, 5 times). This is to correct (modify) the gate opening after confirming that there is a certain degree of reproducibility.

[0042] The above correction value Q may have different values ​​depending on the difference E. The correction value Q may be set, for example, as follows. (1) When the difference E is in a first range higher than the predetermined range, it has a first value greater than 1 (for example, greater than or equal to 1.1 and less than 1.3). (2) When the difference E is in a second range higher than the first range, it has a second value greater than the first value (eg, greater than or equal to 1.3 and less than 1.5). (3) When the difference E is in a third range lower than the predetermined range, it has a third value smaller than 1 (eg, greater than or equal to 0.8 and less than 0.9). (4) When the difference E is in a fourth range lower than the third range, it has a fourth value smaller than the third value (for example, greater than or equal to 0.7 and less than 0.8).

[0043] The above method of determining the correction value Q is just an example, and the correction value Q may be determined by other methods.

[0044] By performing the adjustment according to the above embodiment, a gate opening control condition for stably supplying a predetermined weight of alloy powder from each of the multiple outlets of the vibratory bowl feeder to the press machine can be found. As a result, when the die of the press machine has multiple cavities, it becomes possible to stably supply an appropriate weight of alloy powder to each cavity from one vibratory bowl feeder. [Industrial Applicability]

[0045] The powder feeding system of the present disclosure can be utilized in the manufacture of permanent magnets for use in a wide variety of applications, such as motors for electric vehicles (EV, HV, PHV), motors for industrial equipment, and other motors and home appliances.

Claims

1. a vibratory bowl feeder having a spiral conveying track for conveying powder by vibration and a plurality of discharge openings provided on an outer peripheral surface; a plurality of powder measuring devices respectively assigned to said plurality of discharge openings; a plurality of gate opening / closing devices that branch the powder conveyed by the vibratory bowl feeder from the conveying track and supply the powder to the corresponding powder measuring devices through the plurality of discharge openings; A control device for controlling the plurality of gate opening / closing devices and the plurality of powder measuring devices; Equipped with a control device controls a gate opening degree of each of the gate opening / closing devices based on a weight of the powder measured by each of the powder measuring devices, thereby supplying the powder from the discharge openings to the powder measuring devices, and supplying the powder from the powder measuring devices to a press machine; Each of the plurality of gate opening and closing devices is a gate movable member for opening and closing the discharge opening, the gate movable member moving the powder moving in a region of a predetermined width on the transport track radially outward from the transport track in a gate open state, causing the powder moving on the transport track to drop from the discharge opening into the powder measuring device, and moving the powder moving on the transport track in a circumferential direction of the transport track in a gate closed state; an actuator that drives the gate movable member to adjust the gate opening degree defined by the size of the width; Equipped with the control device controls the gate opening degree of each of the gate opening / closing devices based on the weight of the powder measured by each of the powder measuring devices. Powder feeding system.

2. 2. The powder supply system of claim 1, wherein the control device drives the corresponding gate movable member to reduce the gate opening degree as the weight of the powder measured by each of the plurality of powder measuring devices increases in a gate open state.

3. 3. The powder feeding system of claim 2, wherein the controller incrementally decreases the gate opening as the weight of the powder increases.

4. The control device includes:

4. A powder feeding system according to claim 1, further comprising: a step of discharging the powder in each powder metering device from said powder metering device when the weight of the powder measured by each powder metering device reaches a target weight.

5. The control device includes: measuring a weighing time until the weight of the powder measured by the powder measuring device reaches a target weight; The powder feeding system of claim 4 , wherein the gate opening is altered based on a difference between a target weighing time and the measured weighing time.

6. The control device includes: When the difference is within a predetermined range, the current gate opening is maintained as the gate opening.

6. The powder feeding system of claim 5, wherein when the difference is not within the predetermined range, if a predetermined condition is satisfied, a value obtained by multiplying a current gate opening by a correction value is adopted as the gate opening.

7. 7. A powder feeding system according to claim 6, wherein said predetermined condition is that the number of weighings in which said difference is not within said predetermined range reaches a set value.

8. 8. A powder feeding system according to claim 6 or 7, wherein the correction value has different values ​​depending on the difference.

9. The correction value is a first value greater than 1 when the difference is in a first range that is higher than the predetermined range; when the difference is in a second range higher than the first range, the second value is greater than the first value; a third value less than 1 when the difference is in a third range lower than the predetermined range; 9. A powder feeding system according to claim 8, wherein when the difference is in a fourth range lower than the third range, the difference has a fourth value less than the third value.

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