JPS6161329B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for weighing powder and granular materials.

About the conventional powder weighing machine with dust collector
This will be explained based on the diagram. 1 is a weighing hopper; 2 is a tension type load cell; a rod 2a on the upper surface is connected to a fixed body 3; and a rod 2b on the lower surface is connected to a bracket 4 protruding from the outer peripheral surface of the weighing hopper 1. , whereby the weighing hopper 1 is suspended. 5 is a storage tank for powder and granular material 6 supported by a fixed body (not shown) above the weighing hopper 1; 7 is a discharge chute disposed below the weighing hopper 1; The upper end and the lower end of the weighing hopper 1 are connected to each other by a bellows-shaped telescopic cover 8 that is flexible and airtight. Reference numeral 9 denotes a discharge section connected to the lower end opening of the discharge chute 7, and includes a built-in belt conveyor, screw feeder, etc. (not shown);
are a pair of supply gates disposed at the lower end opening of the storage tank 5, and are equipped with a cylinder device (not shown).
It can be opened and closed by Reference numeral 11 denotes discharge gates respectively disposed at a pair of lower end openings of the weighing hopper 1, which are opened and closed by a cylinder device (not shown). 12 is a cylindrical body externally fitted and fixed to the lower end of the storage tank 5; 13;
14 is a flexible and airtight lid that covers the upper opening of the weighing hopper 1 fixed to the cylindrical body 12; A bellows-shaped telescopic cover, 15 a suction/exhaust port formed in the lid 13, 16 a dust collection pipe of a dust collector (not shown) disposed opposite the suction/exhaust port 15, A slight gap a is formed between the open end of the dust collecting pipe 16 and the intake/exhaust port 15.

In the above configuration, the supply gate 10 is opened to supply the powder or granular material 6 into the weighing hopper 1, and it is weighed by the load cell 2. When a fixed amount is reached, the supply gate 10 is closed and the discharge gate 11 is opened to supply the fixed amount of powder. The granules are discharged into the discharge chute 7 and further discharged by the discharge section 9. Incidentally, when the powder and granular material 6 is supplied into the weighing hopper 1, dust is generated, and the structure is such that this dust is sucked into the dust collecting pipe 16 through the suction and exhaust port 15. However, when a large amount of powder 6 is supplied, the dust often leaks to the outside from the gap a between the dust collecting pipe 16 and the intake/exhaust port 15 and contaminates the surrounding area. Therefore, it is conceivable to make the gap a smaller, but if this is done, the inside of the weighing hopper 1 will become negative pressure during small supply and metering, the weight of the weighing hopper 1 will become lighter, and a weighing error will occur. Also, discharge gate 1
1 is opened to discharge the powder and granular material 6 into the discharge chute 7, excess air in the discharge chute 7 flows into the weighing hopper 1 through the lower end opening of the weighing hopper 1, that is, through the inside of the powder and granular material 6. This promotes the generation of dust, which becomes an obstacle to the discharge and fall of the powder and granular material 6.

The present invention provides a method for measuring powder and granular materials that solves these problems.

Hereinafter, one embodiment of the present invention will be described based on the drawings from FIG. 2 onwards. In this embodiment, the same parts as those in the apparatus shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. 20 is measuring hopper 1
A ventilation pipe arranged along both outer surfaces of the
This allows the inside of the weighing hopper 1 and the inside of the discharge chute 7 to communicate with each other. Reference numeral 21 denotes an intake/exhaust pipe connected to the exhaust port 15, and the intake/exhaust pipe 21 includes a dust collection port 23 to which a dust collection pipe 22 of a dust collector (not shown) is connected, and an air intake/exhaust pipe 23 that communicates with the atmosphere. Mouth 2
4 is provided. 25 is a support shaft 26 at the branch point between the dust collection port 23 and the atmospheric port 24 in the intake/exhaust pipe 21.
This damper is rotatably disposed about the fulcrum and opens and closes the air vent 24. Note that this damper 25 is rotated by a cylinder device or the like. 27 is a filter.

The operation of the above configuration will be explained. First, at the normal stop (before the start of measurement) as shown in Figure 2, both gates 1
0 and 11 are closed, and the damper 25 is left half open since no dust is generated. As a result, outside air is sucked in through the air vent 24, the wind speed in the ventilation pipe 20 is reduced, and the inside of the weighing hopper 1 is brought into a normal pressure state. Therefore, it is a state in which correct measurement can be performed, and in this state, zero adjustment or auto-zero is applied to the load cell 2.

Next, as shown in FIG. 3, the supply gate 10 is fully opened to supply a large amount of powder 6 into the weighing hopper 1.
At the same time, the damper 25 is fully closed or slightly opened. Then, due to the large flow of the powder 6 into the weighing hopper 1, the excess air generated in the hopper 1 is sucked into the dust collecting pipe 22 together with the dust through the exhaust port 15 and the dust collecting port 23.

Next, as shown in FIG. 4, the supply gate 10 is opened halfway and a small amount of the powder 6 is supplied into the weighing hopper 1. At the same time, the damper 25 is also half-opened. During this small supply, the amount of excess air and dust in the metering hopper 1 will be small, but the suction force of the dust collecting pipe 22 will not change. Therefore, if the damper 25 remains in the large supply mode, the suction force will be too strong.
The inside of the weighing hopper 1 becomes negative pressure, which causes a measurement error. However, as mentioned above, since the damper 25 is left half-open, the inside of the weighing hopper 1 does not become negative pressure, and the conditions are the same as before the start of measurement, so there is no measurement error. does not occur.

Next, as shown in FIG. 5, when the powder or granular material 6 in the weighing hopper 1 reaches a fixed amount by weighing by the load cell 2, the supply gate 10 is completely closed. Further, the gate 25 is left as it is (half-open). In this case, even if there is a change in the suction force of the dust collection pipe 22, the damper 25 is half-open and sucks in outside air from the atmosphere port 24, so the influence on the weighing hopper 1 is small, and the capacity of the ventilation pipe 20 is small. If this is sufficient, the wind speed inside the ventilation pipe 20 will be small, there will be no pressure difference between the inside and outside of the weighing hopper 1, and there will be virtually no measurement error.

Next, as shown in FIG. 6, the discharge gate 11 is fully opened to discharge the powder 6 in the weighing hopper 1 into the discharge chute 7. At the same time, damper 2
5 is fully closed or close to fully closed. Since this powder and granular material 6 is discharged in a short period of time, the excess air in the discharge chute 7 is discharged into the ventilation pipe 20 along with the dust.
It enters the weighing hopper 1 through the hopper 1, and releases the negative pressure inside the weighing hopper 1. Further, dust is sucked into the dust collecting pipe 22. In this case, excess air in the discharge chute 7 escapes through the ventilation pipe 20 and does not escape through the lower end opening of the weighing hopper 1, that is, inside the powder 6, so that the powder 6 can be discharged smoothly. It can be done.

Next, as shown in FIG. 7, when the discharge of the granular material 6 is completed, the discharge gate 11 is closed. At the same time, the damper 25 is opened halfway and returned to the state shown in FIG. Therefore, this completes one measurement.

Next, when continuing the second measurement, the supply gate 10 is fully opened to supply a large quantity of powder and granular material 6 as shown in FIG. 8, and at the same time, the damper 2
5 is fully closed or slightly open. In this case, since the powder and granular material 6 in the discharge chute 7 is discharged, the inside of this chute 7 becomes a negative pressure, but excess air in the weighing hopper 1 flows in through the ventilation pipe 20, causing a negative pressure state. Eliminate.

Thereafter, the operation of small supply → fixed amount → discharge is repeated.

In the above embodiment, the intake/exhaust pipe 21 having the dust collection port 23 and the atmosphere port 24 is provided, but the dust collection port 22 is provided in the lid 13.
3 and the atmosphere port 24 may be formed separately, the dust collection port 23 may be connected to the dust collection pipe 22 of the dust collector, and the atmosphere port 24 may be provided with a damper 25. Moreover, it goes without saying that a measuring device such as a lever system may be used in addition to the load cell 2.

As described above, according to the powder weighing method of the present invention, the dust generated when a large amount of powder 6 is fed into the weighing hopper 1 and when the powder 6 is discharged into the discharge chute 7 is Since the damper 25 is fully closed or close to fully closed, the dust collection pipe 22
There is no risk of dust leaking outside and contaminating the surrounding area, unlike in the past. When weighing with the supply gate 10 half-open, the damper 25 is left half-open, and the inside of the weighing hopper 1 and the inside of the discharge chute 7 are communicated with each other through the ventilation pipe 20, so that when a small amount of powder or granules is supplied. Even when suctioning from the dust collection pipe 22 with the same suction force as during large supply during metering, the inside of the metering hopper does not become a negative pressure state, and no metering error occurs.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view showing a conventional example, Figures 2 to 8
The figure is a longitudinal sectional view illustrating the operation of an embodiment of the present invention. 1...Measuring hopper, 2...Load cell (measuring device), 5...Storage tank, 6...Powder/granular material, 7...Discharge chute, 10...Supply gate, 11...Discharge gate, 13...Lid (closed body), 15... intake/exhaust port, 20... ventilation pipe, 21... exhaust pipe, 22...
Dust collection pipe, 23...Dust collection port, 24...Atmospheric port, 25
...damper.

Claims (1)

[Claims] 1 A weighing hopper 1, a weighing device 2 that supports the hopper 1, a powder storage tank 5 provided above the weighing hopper 1, and a discharge chute 7 provided below the weighing hopper 1. In the powder and granular material weighing machine, a dust collection port 23 and an atmospheric air port 24 communicating with the inside of the weighing hopper 1 are formed in the sealing body 13 that seals between the weighing hopper 1 and the storage tank 5. A dust collection pipe 22 of a dust collection device is connected to the dust port 23, a damper 25 is provided to the atmosphere port 24, and the inside of the weighing hopper 1 and the inside of the discharge chute 7 are communicated with each other via the ventilation pipe 20, With the dust collector in operation, the supply gate 10 of the powder storage tank 5 is fully opened to supply a large amount of powder and granules 6 into the weighing hopper 1, and at the same time, the damper 25 is fully closed or slightly opened. Next, the supply gate 10 is opened half-open to supply a small amount of powder 6 into the weighing hopper 1, and at the same time, the damper 25 is half-opened, and then, when the powder and granular material in the weighing hopper 1 reaches a fixed amount, For example, the supply gate 10 is fully closed, then the discharge gate 11 of the weighing hopper 1 is fully opened, and at the same time, the damper 25 is fully closed or close to fully closed, and then the powder and granular material 6 in the weighing hopper 1 is completely closed. A method for weighing powder or granular material, characterized in that the discharge gate 11 is fully closed after the discharge of the powder is completed.