JPH0620984Y2 - Precision powder feeder - Google Patents

Description

[Detailed description of the device] [Industrial application field] In the case where powder is divided from a large storage tank into small lots according to various applications, it is necessary to improve weighing accuracy from the viewpoint of price and quality control of the destination. Is required. The present invention relates to a precision powder supply device effective in such fields.

[Conventional technology and its problems]

As a quantitative cutting device for powder, a screw feeder,
Rotary valve feeders, table feeders, belt feeders, etc. are commonly used. In all of these devices, the supply amount is usually adjusted to be constant by weighing, but in order to bring the weighing accuracy closer to the weighing accuracy limit value of the balance itself by this method, the powder cutting end point should be set. Need to be cut sharply. Therefore, conventionally, an end point proximity signal for weighing is taken out from a scale provided on the powder receiving side, and the signal is used to slow down the speed of the feeder to sharpen the end point cut. However, it is difficult to control the speed of the feeder designed for the purpose of large-scale feed only at the final stage and supply a small amount. Taking the belt feeder as an example, the supply powder is accumulated on the belt to the full width of the belt and is conveyed.Therefore, even if the conveying speed at the final stage is reduced, the amount of powder that falls last is the smallest. It becomes a powder lump with a limited value. Moreover, since there is no steadiness in how the powder is piled up on the belt, it is unavoidable that the weight of each cut-out hatch varies.

As a result, the scale itself Even if it has the accuracy of, the measuring accuracy depends on the physical properties of the powder, but if you look at the powder as a whole, At most Is the limit.

Therefore, the present invention aims to improve the weighing accuracy of the powder by enabling the precision supply by the feeder as described above for the purpose of mass feeding.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention is directed to a powder supply device equipped with a powder supply feeder and a scale for the supplied powder, from a feeder upon receiving a weighing end point proximity signal from the scale. The powder control plate that blocks the powder falling path and its driving means, and the powder accumulated on the powder control plate from a plurality of slits formed in the plate by moving at low speed on the powder control plate by the end point proximity signal. The scraper and the driving means for gradually dropping it until it stops after receiving the end point signal from the weighing machine are provided.

[Action]

According to the conventional device, since the powder mass finally drops from the feeder outlet, this mass is the limit of the weighing accuracy, and moreover,
Poor reproducibility because the size of powder mass is not constant. However, in the device of the present invention, the powder control plate blocks the powder falling path from the feeder outlet when the end point proximity signal from the weighing machine is received, and thereafter, powder is gradually added from the slit of the powder control plate. Since the scraper that can be dropped and scrapes off the powder on the dust control plate will stop instantly at the end signal from the weighing machine,
The end cuts are very sharp and do not have any of the last phenomenon of overfeed of one lump found in conventional equipment. Therefore, the weighing accuracy naturally approaches the maximum sensitivity of the weighing machine.

〔Example〕

An example of the device of the present invention will be described below with reference to the accompanying drawings.

The illustrated apparatus employs a well-known belt feeder 1. When the powder A falling from the end of the belt feeder 1 is received by the subdivision container 2 and the supply amount to this container reaches a predetermined weight, it is sensed. A stop endpoint signal flows from a weighing machine 3 such as a load cell weighing machine to a drive motor (not shown) of the belt feeder 1. This point is an apparatus configuration based on a conventional method.

That is, the device of the present invention is provided with the powder control plate 4 and its driving means 5 and the scraper 6 and its driving means 7 which are large enough to block the powder falling path from the feeder 1 for precise supply. Further, the powder control plate 4 has a plurality of slits 8 opened at intervals, which is different from the conventional device.

The position of the powder control plate 4 can be switched from a retracted point P shown by a chain line to a cutoff point Q of a powder falling path shown by a solid line. It is the drive means 5 provided with a drive source 5a such as a motor that performs the switching. The drive means 5 takes out the weighing end point proximity signal from the weighing machine 3 and operates by this signal.

On the other hand, the scraper 6 is preferably provided with a brush 6a so that it starts to move linearly in response to an end point proximity signal from the weighing machine 3 and moves on the dust control plate 4 at the point Q at a low speed. The movement is performed by the driving means 7 provided with the driving source 7a. The figure uses a motor as a drive source and a rack and pinion for power transmission.

In the device of the present invention configured as described above, when the end point proximity signal from the weighing machine 3 is received, the powder control plate 4 moves from the point P to the point Q to block the powder falling path, and thereby the powder container 2 The steady supply to the plant is temporarily suspended. During this stop period, the falling powder from the feeder is piled up on the non-slit portion of the plate 4 in a striped pattern. However, since the amount of powder received by the plate 4 is limited, it is operated at high speed for large-scale supply. Belt feeder 1
It is desirable to switch to low speed operation or stop at the same time when the plate 4 moves to the Q point.

Then, the scraper 6, which started the low speed movement at the end point proximity signal, moves linearly while brushing on the dust control plate 4,
The powder A deposited on the plate is dropped into the container 2 little by little. Then, when the end point signal from the weighing machine 3 flows at the limit of the sensitivity, the scraper stops instantaneously, and high-precision powder supply is completed.

The width, length and number of the slits 8 and the moving speed of the scraper 6 may be determined in consideration of the powder to be handled and the required weighing accuracy. It is desirable to have an angle of 0 ° or more and 90 ° or less in the traveling direction. If the slits 8 are parallel or at right angles to the progress of the creper, the powder particles will be aggregated and fall to some extent, and the calculation accuracy will be slightly reduced. However, with the slits intersecting the advancing direction of the scraper at an angle of 90 ° or less, the powder accumulated between the adjacent slits is gradually dropped along with the movement of the scraper, thereby improving the weighing accuracy at the end point. A cut damper (not shown) that receives falling powder at the end point signal may be installed under the powder control plate for the purpose of improving accuracy or increasing processing speed, but this damper is adopted or rejected according to various conditions. Should be decided.

As described above, when the predetermined supply is completed, the container 2 is replaced with an empty container, and the residual powder on the plate 4 is dropped into the container after replacement by retreating to the point P of the plate 4, and the same as above. Enter batch operation.

The results of experiments conducted to confirm the effects of this invention will be described below.

Precision of iron compound powder with true specific gravity of 8 g / cm ³ Using a load cell weighing machine of No. 3, a 20 kg packed container was supplied from a belt feeder. When the powder control plate 4 was not used, the feeding accuracy increased as the feeder speed was decreased at the final stage, but still, Best from It was a stop.

On the other hand, a powder control plate 4 with slits of width 3.5 mm, length 100 mm, and array pitch 15 mm opened at an angle of 70 ° in the scraper advancing direction is used to block the powder falling path from the feeder and perform the same operation. Repeatedly, due to the reproducibility of the automatic cycle operation, the container could be filled with an accuracy of approximately ± 4 g. In this case, the accuracy of the load cell weighing machine could be fully utilized for weighing.

The same operation was performed with the slits arranged at right angles to the scraper advancing direction. The result is ± 10g Was the accuracy of.

〔effect〕

As described above, according to the present invention, the powder control plate that blocks the powder drop path from the feeder by the end point proximity signal from the weighing machine is provided, and after blocking the powder drop path with this powder control plate, The powder is dropped little by little from the slit of the dust control plate until the end signal is received by scraping with a scraper, and the falling phenomenon as a powder lump at the end is eliminated, so the weighing accuracy of the scale is fully utilized for actual weighing. It is possible to obtain the effect that the industrial utility value and reliability of the device are enhanced.

[Brief description of drawings]

The attached drawing is a simplified perspective view showing an example of the powder supply apparatus according to the present invention. 1 ... Belt feeder, 2 ... Subdivision container, 3 ... Weighing machine, 4 ... Powder control plate, 5 ... Driving means, 6 ... Scraper, 7 ... Driving means, 8 ... Slit, A ... …powder.

Claims (1)

[Scope of utility model registration request] 1. A powder supply apparatus comprising a powder supply feeder and a weigher for the supplied powder, which receives a weighing end point proximity signal from the weigher and blocks the powder falling path from the feeder. The plate and its driving means and the end point proximity signal are used to move at low speed on the powder control plate and the powder accumulated on the powder control plate is received from the weighing machine through a plurality of slits formed in the plate. A precision powder feeding device comprising a scraper for gradually dropping until stopping and a driving means for the scraper.