Powder supply device and method for manufacturing glass articles

Abstract

To positively prevent a powder from spilling from a discharge port during a stoppage of powder transfer.SOLUTION: A powder feeding device 1 comprises a hopper 2, a feeder 3 that has a transfer passage 4 for transferring a powder P fed from the hopper 2 in a horizontal direction and has a discharge port 7 formed at a downstream end, and a gate member 11 that opens and closes the transfer passage 4. The gate member 11 is rotatably held so that it becomes an inclined position downwardly inclining from upstream toward downstream during a closure of the transfer passage 4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an improved technology for a gate member provided in a feeder of a powder supply device and a method for manufacturing a glass article using the powder supply device.

Background Art

[0002] In the field of powder supply, as a device for horizontally transferring and dropping the powder supplied from a hopper, a powder supply device equipped with a feeder such as a vibratory feeder or a screw feeder is used. In this type of powder supply device, various improvements have been made to accurately drop the required amount of powder.

[0003] As an example, Patent Document 1 discloses a technical solution in which a door plate is provided at the downstream end of the transfer path of a vibratory feeder, and when the transfer of the powder stops (when the vibration stops), the transfer path is closed by the door plate to prevent excess powder from spilling out of the discharge port of the transfer path.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the door plate disclosed in Patent Document 1 closes the transfer path by assuming a vertical posture when the transfer of the powder stops, and prevents excess powder from spilling out of the discharge port (see FIGS. 2(b) and 5(b) of the same document). However, when the door plate dams up the powder in a vertical posture, considering the angle of repose, the powder layer is in a state where it tends to collapse. In such a state, a strong force acts in the direction of pushing open the door plate due to the weight of the powder layer, so that excess powder may still spill out of the discharge port.

[0006] From the above perspective, the present invention aims to reliably prevent excess powder from spilling out of the discharge port when the transfer of powder is stopped. [Means for solving the problem]

[0007] (1) The first aspect of the present invention, which was devised to solve the above problems, is characterized in that it comprises a hopper, a feeder having a transfer path that transfers powder supplied from the hopper laterally and has a discharge port formed at its downstream end, and a gate member that opens and closes the transfer path, wherein the gate member is rotatably held in an inclined position that slopes downward from the upstream side to the downstream side when the transfer path is closed.

[0008] With this configuration, the gate member is held rotatably and assumes an inclined position with the aforementioned direction when the transport path is closed (hereinafter simply referred to as the inclined position). Therefore, when the transport of powder is stopped, the gate member is affected by its own weight and pushes down the powder to close the transport path. At this time, because the gate member is in an inclined position, the layer of powder that is blocked by the gate member is less likely to collapse. When the layer of powder is less likely to collapse in this way, the force acting to push the gate member open by the weight of the blocked layer of powder is weakened, so that excess powder does not spill out of the discharge port can be reliably prevented. Note that the gate member can assume an inclined position when the transport of powder is stopped solely by its own weight, but the downward force acting from the gate member on the layer of powder may be adjusted using a spring or the like.

[0009] (2) In the configuration of (1) above, it is preferable that the gate member contacts the bottom of the transport path to close the transport path when the transport of the powder is stopped.

[0010] This method effectively prevents excess powder from spilling out of the discharge port when the powder transfer is stopped.

[0011] (3) In the configuration of (1) above, it is preferable that the gate member contacts the lower end of the discharge port to close the transfer path when the transfer of the powder is stopped.

[0012] In this way, when the transfer of powder stops, the gate member will come into contact with the lower end of the discharge port, thus more reliably preventing excess powder from spilling out of the discharge port.

[0013] (4) In the configuration of (2) or (3) above, if the inclination angle of the gate member with respect to the horizontal plane when the transfer of the powder is stopped is α and the angle of repose of the powder is β, it is preferable that the relationship α ≤ β + 30° is satisfied.

[0014] In this way, the angle of the gate member's inclination when powder transfer stops becomes an appropriate angle that takes the angle of repose into account. This also more reliably prevents excess powder from spilling out of the discharge port. The above relationship is preferably α ≤ β + 15°, and more preferably α ≤ β.

[0015] (5) In any of the configurations described in (1) to (4) above, the feeder may be a vibrating feeder, and the powder may be glass raw material.

[0016] (6) A second aspect of the present invention, which was devised to solve the above problems, is a method for manufacturing a glass article, characterized by comprising: a weighing step of weighing glass raw material as powder that has fallen from the discharge port of the transfer path in a feeder having any of the configurations of (1) to (5) above; a melting step of melting the glass raw material weighed in the weighing step to produce molten glass; and a molding step of molding the molten glass produced in the melting step.

[0017] This method improves the accuracy of matching the amount of glass raw material dropped in the weighing process to the target amount, thereby enabling the weighing process and subsequent melting and molding processes to proceed smoothly. [Effects of the Invention]

[0018] According to the present invention, it is possible to reliably prevent the spillage of excess powder from the discharge port when the transfer of the powder stops.

Brief Description of the Drawings

[0019] [Figure 1] It is a longitudinal side view showing the overall configuration of the powder supply device according to an embodiment of the present invention. [Figure 2] It is a perspective view of a main part showing the peripheral structure of a gate member which is a component of the powder supply device according to an embodiment of the present invention. [Figure 3] It is a longitudinal side view showing an enlarged view of the main part of the powder supply device according to an embodiment of the present invention. [Figure 4] It is a longitudinal side view showing an enlarged view of the main part of the powder supply device according to an embodiment of the present invention. [Figure 5] It is a longitudinal side view showing an enlarged view of the main part of a first modification of the powder supply device according to an embodiment of the present invention. [Figure 6] It is a longitudinal side view showing an enlarged view of the main part of a second modification of the powder supply device according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0020] Hereinafter, a powder supply device and a method for manufacturing a glass article according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0021] FIG. 1 is a longitudinal side view showing the overall configuration of the powder supply device 1. As shown in the figure, the powder supply device 1 includes a hopper 2 and a feeder 3 disposed below the hopper 2.

[0022] The hopper 2 stores powder P in its internal space. In this embodiment, powder P is a glass raw material, but is not limited to this. The glass raw material is not limited to a mixed raw material obtained by mixing multiple types or brands to obtain glass of a desired composition, but may also be a single raw material consisting of a single type or brand before mixing. A supply port 2a for supplying powder P into the feeder 3 is formed at the lower end of the hopper 2. It is preferable to provide a stirring mechanism (not shown) such as gears in the internal space of the hopper 2.

[0023] The feeder 3 comprises a transport path 4 for transporting the powder P supplied from the hopper 2 in a lateral direction (preferably horizontally), and an excitation means 6 for applying vibration to the transport path wall 5 that forms the transport path 4. In this embodiment, the feeder 3 is a vibrating feeder. Therefore, the powder P is transported downstream (towards the direction of arrow A) by vibration.

[0024] The transport path wall 5 is composed of a bottom wall portion 5a that runs horizontally, two side wall portions 5b that run vertically, and an upper wall portion 5c that covers the top and runs horizontally. Therefore, the cross-section of the transport path 4 is rectangular. The bottom wall portion 5a and the two side wall portions 5b are integrally formed, but the cover (upper wall portion 5c) can be removed from the side wall portions 5b.

[0025] An outlet 7 for discharging powder P is formed at the downstream end of the transfer path 4. In this embodiment, a drop guide path 8 is provided that communicates with the outlet 7. The guide path wall 9 forming the drop guide path 8 is composed of an upper extension wall portion 9a, two side extension wall portions 9b, a first end wall portion 9c, and a second end wall portion 9d. The upper extension wall portion 9a extends downstream from the upper wall portion 5c. The two side extension wall portions 9b each extend downstream from the two side wall portions 5b and also extend downward from their extension portions. The first end wall portion 9c is connected to the respective downstream ends of the upper extension wall portion 9a and the two side extension wall portions 9b. The second end wall portion 9d extends downward from the downstream end of the bottom wall portion 5a and is connected to the upstream ends of the downward extension portions of the two side extension wall portions 9b.

[0026] Below the drop guide path 8, a measuring device 10 is installed to measure the amount of powder P that falls. Therefore, the powder P discharged from the outlet 7 of the transport path 4 and falling is supplied to the measuring device 10. When the measuring device 10 indicates that the amount of powder P that has fallen matches the target amount, this is detected by a sensor or an operator, and the vibration applied from the vibration means 6 to the transport path wall 5 of the feeder 3 stops. Simultaneously with the cessation of this vibration, the transport of powder P within the transport path 4 stops.

[0027] A plate-shaped gate member (flap gate) 11 is provided in the transport path 4. The gate member 11 is held in an inclined position (hereinafter simply referred to as the inclined position) that slopes downward from the upstream side to the downstream side. Specifically, the gate member 11 is held in the inclined position in both cases, as shown by the solid line in Figure 1 when the transport path 4 is closed at its downstream end and as shown by the dashed line in the same figure when it is open. The gate member 11 can be made of various metals or resins, but in this embodiment it is made of stainless steel.

[0028] The gate member 11 is mounted in the manner shown in Figure 2, for example. As shown in the figure, a bearing member 12 is attached to the upper end (upstream end) of the gate member 11, and a support shaft 13 is inserted through the shaft hole of the bearing member 12. The support shaft 13 is fixed to the lower ends of two vertically extending support columns 14. The two support columns 14 are fixed to the upper wall portion 5c, passing through it. As a result, the gate member 11 is held rotatably around the support shaft 13 located at the top of the transport path 4, and tilts due to its own weight.

[0029] Figure 3 is an enlarged longitudinal cross-sectional side view of the main part showing the state when the transfer of powder P in the transfer path 4 stops due to the cessation of vibration of the transfer path wall 5. As shown in the figure, when the transfer of powder P stops, the gate member 11 rotates clockwise C around the support shaft 13 due to its own weight, and as shown in the figure, the lower end 11a of the gate member 11 comes into contact with the downstream end of the bottom surface 4a of the transfer path 4. More specifically, the lower end 11a of the gate member 11 comes into contact with the downstream end 4aa of the bottom surface 4a of the transfer path 4, that is, the lower end of the discharge port 7.

[0030] If the inclination angle of the gate member 11 with respect to the horizontal plane is α and the angle of repose of the powder P is β, then the relationship α ≤ β + 30° is satisfied. With this relationship, when the transfer is stopped, the layer of powder P blocked by the gate member 11 is less likely to collapse. When the layer of powder P is in such a state that it is less likely to collapse, the force acting in the direction of pushing open the gate member 11 due to the weight of the blocked layer of powder P is weakened. As a result, it is possible to reliably prevent excess powder from spilling out of the discharge port 7 and being supplied to the weighing device 10. Taking this into consideration, the above relationship is more preferably α ≤ β + 15°, and even more preferably α ≤ β. In the case of glass raw materials, the angle of repose of the powder P is, for example, 10° to 40°.

[0031] Figure 4 is an enlarged longitudinal cross-sectional side view of the main part showing the state when powder P is transported in the transport path 4 due to the vibration of the transport path wall 5. As shown in the figure, when powder P is transported, the powder P is forcibly transported downstream by the vibration, so an upward force from the powder P acts on the lower surface 11b of the gate member 11. As a result, the gate member 11 rotates counterclockwise D around the support shaft 13 against its own weight. Consequently, the gate member 11 is pushed open in the manner shown in the figure. At this time, the inclination angle of the gate member 11 with respect to the horizontal plane becomes even smaller than the inclination angle α when the transport is stopped as described above. Therefore, a strong force from the gate member 11 no longer acts on the layer of powder P being transported in the direction opposite to the transport direction. In other words, the force from the gate member 11 acting in the direction that hinders the transport of powder P is weakened. This ensures that the powder P falls smoothly from the discharge port 7, and reduces variations in the amount of powder P supplied per unit time (the amount of powder P falling from the discharge port 7). As a result, the supply amount can be stabilized.

[0032] Next, a method for manufacturing a glass article according to an embodiment of the present invention will be described.

[0033] The manufacturing method for this glass article comprises a weighing step, a melting step, and a molding step. The weighing step is the process of weighing the glass raw material as powder P that falls from the discharge port 7 of the transfer path 4 in the feeder 3 described above. The melting step is the process of melting the glass raw material weighed in the weighing step to produce molten glass. The molding step is the process of molding the molten glass produced in the melting step. In the molding step, a glass ribbon is formed, for example, by the overflow method. The glass plate cut from the molded glass ribbon is used as a substrate or cover in displays such as liquid crystal displays and organic EL displays.

[0034] According to this method of manufacturing glass articles, the accuracy of matching the amount of glass raw material dropped during the weighing process to the target amount is improved, resulting in less variation in glass composition and the ability to obtain high-quality glass articles.

[0035] Although the powder supply device 1 and the method for manufacturing glass articles according to embodiments of the present invention have been described above, the present invention is not limited thereto, and various variations are possible without departing from the spirit of the invention.

[0036] In the above embodiment, the case where the powder P fills or nearly fills the transport path 4 (when a large amount is being transported) was illustrated. However, when transporting a small amount or a minute amount of powder P, a large gap is provided between the layer of powder P and the upper surface 4b of the transport path 4, as shown in Figure 5. In this case, it is preferable to provide a baffle plate or the like at an intermediate position in the transport direction of the powder P in the transport path 4 to adjust the amount of powder P supplied.

[0037] In the above embodiment, the case where the lower end 11a of the gate member 11 contacts the lower end 4aa of the discharge port 7 when the transfer of the powder P is stopped was illustrated. However, as shown in Figure 5, the lower end 11a of the gate member 11 may contact the bottom surface 4a of the transfer path 4 at a position upstream of the downstream end (lower end of the discharge port 7) 4aa. From the viewpoint of more reliably preventing the spillage of excess powder, it is preferable for the gate member 11 to contact the lower end 4aa of the discharge port 7.

[0038] As shown in Figure 6, when the transfer of the powder P is stopped, the lower surface 11b of the gate member 11 may be in contact with the lower end 4aa of the discharge port 7. If the lower end 11a of the gate member 11 is in contact with the lower end 4aa of the discharge port 7, then if the gate member 11 is displaced, the lower end 11a of the gate member 11 may not be in contact with the lower end 4aa of the discharge port 7, but may instead be in contact with the downstream end of the bottom surface 4a of the transfer path 4. If the lower surface 11b of the gate member 11 is in contact with the lower end 4aa of the discharge port 7, then even if the gate member 11 is displaced, the gate member 11 can be made to contact the lower end 4aa of the discharge port 7. For this reason, it is preferable to have the lower surface 11b of the gate member 11 in contact with the lower end 4aa of the discharge port 7.

[0039] In the above embodiment, the gate member 11 is designed to tilt when the transfer of the powder P stops due to its own weight alone. However, the downward force acting from the gate member 11 onto the powder P layer may be adjusted using a spring or the like. The gate member 11 may also be equipped with a weight to adjust the downward force. Furthermore, multiple types of gate members 11 with different masses may be prepared, and the downward force may be adjusted by exchanging the gate member 11. [Examples]

[0040] Examples and comparative examples of the present invention will be described below. Table 1 below shows Examples 1 and 2 and comparative examples. In all tests, barium chloride, a glass raw material, was used as the powder P, and its angle of repose β was 20°. The target amount was 3 kg, and the tolerance range was ±0.02 kg. 10,000 weighings were performed in each test, and the frequency of occurrences exceeding the tolerance range was calculated. In Table 1 below, "angle α of gate member" refers to the inclination angle α of the gate member 11 shown in Figure 3 described above.

[0041] [Table 1]

[0042] According to Table 1 above, in the comparative example, the frequency of occurrences exceeding the acceptable range was 0.05%. In Examples 1 and 2, the frequency of occurrence was reduced by tilting the gate member 11. In Example 1, compared to Example 2, by bringing the tilt angle α of the gate member 11 closer to the angle of repose β, the weighing error did not exceed the acceptable range, and no problems occurred at all. Considering these results, it can be inferred that even if the angle α of the gate member is greater than β+15°, if the angle is moderately smaller than 90°, for example, β+30°, the weighing error will be small and no problems will occur. [Explanation of symbols]

[0043] 1 Powder feeding device 2 Hoppers 3 feeders 4 Transfer route 4a Bottom surface of the transport path (bottom of the transport path) 4aa Downstream end of the bottom of the transfer path (lower end of the discharge port) 7 Outlet 11 Gate member P powder α Incline angle

Claims

1. The system comprises a hopper, a feeder having a transfer path that transfers powder supplied from the hopper laterally and has a discharge port formed at its downstream end, and a gate member that opens and closes the transfer path. The powder supply device is characterized in that the gate member is rotatably held such that it assumes an inclined position that slopes downward from the upstream side to the downstream side when the transport path is closed.

2. The powder supply device according to claim 1, characterized in that when the transfer of the powder is stopped, the gate member contacts the bottom of the transfer path to close the transfer path.

3. The powder supply device according to claim 1, characterized in that when the transfer of the powder is stopped, the gate member contacts the lower end of the discharge port to close the transfer path.

4. The powder supply device according to claim 2, characterized in that when the inclination angle of the gate member with respect to the horizontal plane at the time the transfer of the powder stops is α, and the angle of repose of the powder is β, the relationship α ≤ β + 30° is satisfied.

5. The powder supply device according to any one of claims 1 to 4, characterized in that the feeder is a vibrating feeder.

6. The powder supply device according to any one of claims 1 to 4, characterized in that the powder is a glass raw material.

7. A method for manufacturing a glass article, comprising: a weighing step of weighing glass raw material that has fallen from the discharge port of the transfer path in a feeder of the powder supply device described in claim 6; a melting step of melting the glass raw material weighed in the weighing step to produce molten glass; and a molding step of shaping the molten glass produced in the melting step.

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