JP7843966B2 - Powder supply device and method for manufacturing glass articles - Google Patents

Description

This invention relates to an improved technique for the gate member of a feeder in a powder supply device, and to a method for manufacturing glass articles using this powder supply device.

In the field of powder supply, powder supply devices equipped with feeders such as vibrating feeders and screw feeders are used to transport and drop powder supplied from a hopper in a lateral direction. Various improvements have been made to these types of powder supply devices to accurately drop the required amount of powder.

As an example, Patent Document 1 discloses a technical method in which a door plate is provided at the downstream end of the transfer path of a vibrating feeder, and the transfer path is closed with the door plate when the transfer of powder stops (when the vibration stops), thereby preventing excess powder from spilling out of the discharge port of the transfer path.

Japanese Patent Publication No. 2018-70340

Incidentally, the door plate disclosed in Patent Document 1 closes the transport path by becoming vertical when powder transport stops, preventing excess powder from spilling out of the discharge port (see Figures 2(b) and 5(b) of the same document). However, when the door plate dams the powder in a vertical position, considering the angle of repose, the powder layer will tend to collapse. In this state, a strong force acts in the direction of pushing the door plate open due to the weight of the powder layer, so excess powder may still spill out of the discharge port.

From the above perspective, the present invention aims to reliably prevent excess powder from spilling out of the discharge port when powder transfer is stopped.

(1) The first aspect of the present invention, devised to solve the above problems, is characterized by comprising 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.

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, under the influence of its own weight, pushes down the powder and closes the transport path. At this time, because the gate member is in an inclined position, the layer of powder held back by the gate member becomes less likely to collapse. When the powder layer is less likely to collapse in this way, the force acting to push the gate member open due to the weight of the held-back powder layer is weakened, thus reliably preventing excess powder from spilling out of the discharge port. While the gate member can assume an inclined position when powder transport is stopped solely by its own weight, the downward force acting from the gate member on the powder layer may be adjusted using a spring or the like.

(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.

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

(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.

In this configuration, when powder transfer 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 port.

(4) In the configuration of (2) or (3) above, it is preferable that the relationship α ≤ β + 30° is satisfied 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.

This method ensures that the inclination angle of the gate member when powder transfer stops is appropriate, taking 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.

(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.

(6) A second aspect of the present invention, 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 (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.

This method improves the accuracy of matching the amount of glass raw material dropped during the weighing process to the target amount, thereby enabling smoother weighing, melting, and molding processes.

According to the present invention, it is possible to reliably prevent excess powder from spilling out of the discharge port when powder transfer is stopped.

This is a longitudinal cross-sectional view showing the overall configuration of a powder supply device according to an embodiment of the present invention. This is a perspective view of the main part showing the peripheral structure of a gate member, which is a component of a powder supply device according to an embodiment of the present invention. This is a magnified view of the main part of the powder supply device according to an embodiment of the present invention. This is a magnified view of the main part of the powder supply device according to an embodiment of the present invention. This is a magnified view of the main part of the first modified example of the powder supply device according to the present invention. This is a magnified view of the main part of a second modified example of the powder supply device according to an embodiment of the present invention.

The following describes a powder supply apparatus and a method for manufacturing glass articles according to embodiments of the present invention, with reference to the accompanying drawings.

Figure 1 is a longitudinal cross-sectional side view showing the overall configuration of the powder supply device 1. As shown in the figure, the powder supply device 1 comprises a hopper 2 and a feeder 3 located below the hopper 2.

The hopper 2 stores powder P in its internal space. In this embodiment, powder P is 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 equip the internal space of the hopper 2 with a stirring mechanism such as gears (not shown).

The feeder 3 comprises a transfer 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 transfer path wall 5 forming the transfer path 4. In this embodiment, the feeder 3 is a vibrating feeder. Therefore, the powder P is transported downstream (in the direction of arrow A) by vibration.

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) is removable from the side wall portions 5b.

A discharge port 7 for discharging powder P is formed at the downstream end of the transfer path 4. In this embodiment, a drop guide path 8 communicating with the discharge port 7 is provided. 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 respective extension portions. The first end wall portion 9c is connected to the 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.

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 has reached the target amount, this is detected by a sensor or operator, and the vibration applied by 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.

A plate-shaped gate member (flap gate) 11 is installed 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 both when the transport path 4 is closed at its downstream end, as shown by the solid line in Figure 1, and when it is opened, as shown by the dashed line in the same figure. The gate member 11 can be made of various metals or resins, but in this embodiment, it is made of stainless steel.

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 axial 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.

Figure 3 is an enlarged longitudinal cross-sectional side view of a key part showing the state when the transfer of powder P within 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, causing the lower end 11a of the gate member 11 to contact the downstream end of the bottom surface 4a of the transfer path 4, as shown in the figure. More specifically, the lower end 11a of the gate member 11 contacts the downstream end 4aa of the bottom surface 4a of the transfer path 4, i.e., the lower end of the discharge port 7.

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. Under this relationship, the layer of powder P dammed by the gate member 11 is less likely to collapse when the transfer is stopped. When the layer of powder P is less likely to collapse in this way, the force acting to push the gate member 11 open due to the weight of the dammed 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. Considering this, the above relationship is more preferably α ≤ β + 15°, and even more preferably α ≤ β. Note that in the case of glass raw materials, the angle of repose of the powder P is, for example, 10° to 40°.

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. As a result, 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 in the direction opposite to the transport direction no longer acts on the layer of powder P being transported. 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 smooth dropping of the powder P from the discharge port 7, reducing variations in the supply rate of powder P per unit time (the amount of powder P dropping from the discharge port 7). As a result, the supply rate can be stabilized.

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

This method for manufacturing glass articles comprises a weighing step, a melting step, and a molding step. The weighing step involves 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 involves melting the glass raw material weighed in the weighing step to produce molten glass. The molding step involves shaping 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.

This method of manufacturing glass articles improves the accuracy of matching the amount of glass raw material dropped to the target amount during the weighing process, resulting in less variation in glass composition and the ability to obtain high-quality glass articles.

The above describes the powder supply device 1 and the method for manufacturing glass articles according to embodiments of the present invention. However, the present invention is not limited thereto, and various variations are possible without departing from its essence.

In the above embodiment, the case where the powder P fills or nearly fills the transfer path 4 (when performing large-volume transfer) was illustrated. However, when transferring small or minute amounts of powder P, a large gap is provided between the layer of powder P and the upper surface 4b of the transfer 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 transfer direction of the powder P in the transfer path 4 to adjust the amount of powder P supplied.

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 stops 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.

As shown in Figure 6, the lower surface 11b of the gate member 11 may be configured to contact the lower end 4aa of the discharge port 7 when the transfer of the powder P is stopped. If the lower end 11a of the gate member 11 contacts the lower end 4aa of the discharge port 7, a displacement of the gate member 11 may cause the lower end 11a to contact the downstream end of the bottom surface 4a of the transfer path 4 without contacting the lower end 4aa of the discharge port 7. By configuring the lower surface 11b of the gate member 11 to contact the lower end 4aa of the discharge port 7, even if a displacement occurs, the gate member 11 can be made to contact the lower end 4aa of the discharge port 7. Therefore, it is preferable to configure the lower surface 11b of the gate member 11 to contact the lower end 4aa of the discharge port 7.

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. Furthermore, the gate member 11 may be equipped with a weight to adjust the downward force. Additionally, multiple types of gate members 11 with different masses may be prepared, and the downward force may be adjusted by swapping the gate members 11.

The following describes examples and comparative examples of the present invention. Table 1 below shows Examples 1 and 2, as well as 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. Each test involved 10,000 weighings, and the frequency of occurrences exceeding the tolerance range was calculated. In Table 1 below, "angle α of the gate member" refers to the inclination angle α of the gate member 11 shown in Figure 3 described above.

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.

1. Powder supply device 2. Hopper 3. Feeder 4. Transfer path 4a. Bottom surface of the transfer path (bottom of the transfer path)
4aa Downstream end of the bottom surface of the transport path (lower end of the discharge port)
7 Discharge port 11 Gate member P Powder α Inclination angle

Claims (7)

The system comprises a hopper, a feeder having a transfer path that transports 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. The powder supply device according to claim 1, characterized in that when the transfer of the powder stops, the gate member contacts the bottom of the transfer path to close the transfer path. The powder supply device according to claim 1, characterized in that when the transfer of the powder stops, the gate member contacts the lower end of the discharge port to close the transfer path. 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. The powder supply apparatus according to any one of claims 1 to 4, characterized in that the feeder is a vibrating feeder. The powder supply apparatus according to any one of claims 1 to 4, characterized in that the powder is a glass raw material. A method for manufacturing a glass article, comprising: a weighing step of weighing the glass raw material that has fallen from the discharge port of the transfer path in the 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.