JPH032825Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a powder supply device for supplying powder or granules to a weighing machine using a screw feeder.

<Conventional technology> Conventionally, as a feeding device for this type of powder or granular material,
There is one described in No. 58-187532. As shown in FIG. 3, this device uses a screw feeder 33 provided at the lower part of the reservoir hopper 31 to feed brake material raw material 32 such as steel wool as powder stored in the reservoir hopper 31. A loosening fitting 36 is fixed to the exit side tip of a screw shaft 33a driven by a motor 35, which is to be transferred to a weighing machine 34. This loosening fitting 36 is constructed by fixing a disk 36a to the tip of the screw shaft 33a on the exit side, and having a threaded rod 36b protruding from the disk 36a toward the screw 33c. And the above threaded rod 3
The brake material raw material 32 transferred at 6b is loosened and its flow is made uniform to improve the measuring accuracy of the weighing machine 34.

By the way, the above-mentioned brake material raw materials are used in the most important control mechanism of automobiles, so there are strict requirements for quality, and the weighing machines that weigh them are also required to have high measuring accuracy, for example, within ±1 g for 100 g. be done. Generally, in order to obtain high measurement accuracy in automatic quantitative weighing of powder or granular materials, the most important thing is how to uniformly and stably supply the powder or granular material to be measured to the weighing machine without variation.

<Problems to be Solved by the Invention> By the way, the brake material raw material 32 is a granular material in which a fibrous material such as steel wool is entangled, and cannot be loosened sufficiently finely by the loosening tool 36. In addition, since the reservoir hopper 31 and the weighing machine 34 are connected by a single screw feeder 33, due to fluctuations and pulsations in the apparent specific gravity of the powder and granular material within the screw feeder 33,
The amount of powder and granular material supplied varies, and the amount of powder and granular material flowing into the weighing machine 34 is not constant. Therefore, there was a problem that the required high precision measurement could not be performed.

Therefore, the purpose of the present invention is to provide a powder supply device that can improve the weighing accuracy and weighing efficiency of a weighing machine by reducing the layer thickness of the powder and making it uniform. The goal is to provide the following.

<Means for Solving the Problems> In order to achieve the above object, the configuration of the present invention is such that an upstream screw feeder is provided at the upper stage, and powder and granular material is supplied from the upstream screw feeder, The present invention is characterized in that a downstream screw feeder having a larger conveying capacity than the upstream screw feeder is provided at the lower stage.

<Function> Powder is supplied to the downstream screw feeder by the upstream screw feeder located in the upper stage, and the downstream screw feeder has a larger conveyance capacity than the upstream screw feeder. Due to the conveyance capacity, the layer thickness of the powder in the downstream screw feeder becomes thinner than the layer thickness of the powder in the upstream screw feeder, and the powder and granule are fed to the weighing machine. The amount is equalized.

<Example> Hereinafter, the present invention will be explained in detail with reference to the illustrated example.

In FIG. 1, 1 is a reservoir hopper for storing powder and granular material 2, 3 is an upstream screw feeder provided horizontally in the lower part of this reservoir hopper 1, and 4 is the tip of this screw feeder 3, i.e. A loosening device 5 provided opposite the outlet is provided horizontally below the loosening device 4, and a downstream screw feeder which rotates at a higher speed than the upstream screw feeder 3 and has a larger conveying capacity; 6 is a damper provided at the outlet 5d opening below the downstream screw feeder 5; 7 is an air cylinder that opens and closes the damper 6; 8 is a weighing machine that automatically weighs the powder and granules; 9 is a screw This is a control device that controls the feeders 3 and 5, the loosening device 4, the air cylinder 7, and the weighing machine 8.

The upstream screw feeder 3 supports a shaft 3a provided with a screw 3c in the horizontal direction with a bearing 3b, and is rotationally driven by a speed control motor 10. The above loosening device 4
A shaft 4a disposed on an extension line of the shaft 3a is supported by a bearing 4b, and a speed control motor 11 drives the shaft 4a to rotate in a direction opposite to the rotational direction of the shaft 3a. 4d is fixed, and this disk 4d
A threaded rod 4e is provided protruding toward the screw 3b side. The above downstream screw feeder 5
A screw 5c is provided on the shaft 5a, a loosening fitting 20 is fixed to the tip, the shaft 5a is supported by a bearing 5b, and a pulse motor 12 is installed.
It is designed to be driven by rotation. The loosening fitting 20 has a disk 20a fixed to the tip thereof, and a threaded rod 20 attached to the disk 20a toward the screw 5c.
It is formed by protruding b. The air cylinder 7 is fixed to a base 14 by a cylinder holder 13, and the damper 6 is opened and closed by moving the rod 7a up and down. The weighing machine 8 has a weighing hopper 8a disposed at the lower part of the outlet 5d suspended from a load cell 8c by a connecting rod 8b, and a gate 8d for discharging the powder after weighing is provided at the lower end of the weighing hopper 8a. establish.

The control device 9 includes a target quantitative value setting device 15,
Powder supply reduction start amount setting device 16, comparison calculation circuit 17, speed control motor 10, 1
The motor includes a speed control motor drive circuit 18 that selectively drives the motor 1 at two speeds, low speed and high speed, and a pulse motor drive circuit 19 that drives the pulse motor 12. The comparison calculation circuit 17 is
The weight W ₀ of the powder or granular material in the weighing hopper 8a is input from the load cell 8c, the target quantitative value W ₁ of the powder or granular material is input from the target quantitative value setting device 15, and the weight of the powder or granular material is input from the supply reduction start amount setting device. From the starting amount of supply decrease W ₂ , the weight W ₀ of the powder and granular material increases and becomes W ₀ =
_W2 , a low speed command signal for driving the speed control motors 10, 11 at low speed is sent to the speed control motors 10, 1 via the speed control motor drive circuit 18.
1, and when W ₂ < W ₀ < W ₁ , (W ₀ −
A deceleration command signal for driving the pulse motor 12 at a speed inversely proportional to the calculated value (W ₀ - W ₂ )/(W 1 - W ₂ ) by calculating _W 2 ₎ /(W ₁ - W ₂ ). is output to the pulse motor 12 via the pulse motor drive circuit 19, and when W ₀ =W ₁ , a stop command signal is output to both drive circuits 18 and 19 and an operation signal to the air cylinder.

In the powder and granular material supply device having the above configuration, the powder and granular material 2 in the reservoir hopper 1 is transferred to the exit side of the screw feeder 3 by a screw 3c provided on a shaft 3a driven by a speed control motor 10. Ru. Then, it is finely loosened by loosening metal fittings 4d and 4e provided at the tip of the shaft 4a of the loosening device 4, which is driven by the speed control motor 11 in the opposite direction to the shaft 3a, and is fed to the screw feeder 5 in the lower stage. be done. In this case, for example, the speed control motors 10 and 11 controlled by the speed control motor drive circuit 18 have a high rotational speed of 2r.pm.
and 20r.pm. Further, for example, the gap l between the tip of the screw 3c and the tip of the threaded rod 4e is 1 mm, and the diameter D ₁ of the screw 3c is 1 mm as shown in FIG.
The width L of the outlet of the reservoir hopper 1 is 50 mm, so that the granular material 2 does not undergo a crosslinking phenomenon at the outlet, is more finely loosened, and is smoothly supplied downward.

Next, the granular material supplied to the downstream screw feeder 5 is transferred to the exit side of the screw feeder 5 by a screw 5c provided on a shaft 5a driven by a pulse motor 12, and is transferred to the exit side of the screw feeder 5. It is finely loosened with a loosening metal fitting 20 provided in the.
Then, it is supplied to the weighing hopper 8a of the weighing machine 8 from the outlet 5d where the damper 6 is opened by the air cylinder 7. In this case, pulse motor drive circuit 1
The pulse motor 12 controlled by 9 is the speed control motor 1 of the screw feeder 3.
Since it rotates at a much higher speed than zero, for example, 30 rpm, the layer thickness of the powder to be transported becomes thinner, the pulsation of the powder is reduced, and the powder is transported uniformly. Therefore, the weighing accuracy and weighing efficiency of the weighing machine are improved. In addition, since the layer thickness is thin and uniformly conveyed in this way, the loosening effect of the loosening metal fitting 20 is further enhanced, the fineness and uniformity of the powder and granules are promoted, and the weighing accuracy and weighing efficiency of the weighing machine are further improved. improves. In addition, the diameter D ₂ of the screw 5c is, for example, 25
mm.

The weight _W0 of the powder and granular material thus supplied to the weighing hopper 8a is transferred to the load cell 8c via the connecting rod 8b.
The signal is transmitted to and detected as an electrical signal, and is input to the comparison calculation circuit 17. The comparison calculation circuit 17 is
When the weight W ₀ of the powder reaches the supply reduction start amount W ₂ , a low speed command signal is output to the speed control motor drive circuit 18, and (W ₀ −
W ₂ )/(W ₁ −W ₂ ) is calculated, and a deceleration command signal proportional to the calculated value is output to the pulse motor 12 via the pulse motor drive circuit 19. In response to this, the speed control motor drive circuit 18 controls the speed control motor 1.
0 and 11 for example 1r.pm and 10r.pm respectively
While rotating at low speed, the pulse motor drive circuit 1
9 decreases the rotational speed of the pulse motor 12 in proportion to the remaining amount of powder and granular material to be supplied, thereby gradually decreasing the amount of powder and granular material supplied to the weighing hopper 8a. Therefore, in the vicinity of the target quantitative value, the supply of powder or granular material is almost eliminated, thereby reducing the dispersion of the measured value and improving the measuring accuracy.

In this way, the weight of the powder or granule in the weighing hopper 8a W ₀
When becomes the target quantitative value W ₁ , the comparison calculation circuit 1
7 outputs a signal to stop the speed control motors 10, 11 and the pulse motor 12, respectively, via the speed control motor drive circuit 18 and the pulse motor drive circuit 19, and operates the air cylinder 7 to stop the damper 6.
to close the exit 5d. In this manner, after the automatic quantitative measurement is completed, the gate 8d at the lower end of the weighing hopper 8a is opened, and the powder or granules are discharged to the next process.

In the above embodiment, both screw feeders 3, 5
The loosening devices 4 and 20 are provided with an appropriate gap at the tip of the screw 3c, and the loosening device 4 rotates in the opposite direction to the screw 3c facing the screw 3c. It can be finely loosened, and more uniform and stable powder and granules can be supplied, improving weighing accuracy and efficiency. Further, as the weight of the powder or granular material in the weighing hopper 8a approaches the target quantitative value, the control device 9 controls the pulse motor 12 so that the supply amount gradually decreases toward zero, and when the target quantitative value is reached, the output 5d
Since the damper 6 is closed, weighing accuracy and weighing efficiency are significantly improved. As an example, according to a conventional powder supply device, the defective rate was 3 to 5% for a standard deviation of σ = 0.5 g and a measurement accuracy of ±1 g for a weighing of 100 g. In the experiment conducted using the example, σ=
0.3g, the above defect rate was improved to 0%.

<Effects of the invention> As is clear from the above explanation, the powder and granular material supplying device of the present invention includes an upstream screw feeder and an upstream screw feeder provided below the feeder and connected to a weighing machine. Since the downstream screw feeder has a larger conveyance capacity than the feeder, the layer thickness of the powder in the downstream screw feeder becomes thinner, and the amount of powder supplied to the weighing machine becomes uniform. is,
Therefore, the weighing accuracy and weighing efficiency of the weighing machine can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a cross-sectional view along the line taken from FIG. 1, and FIG. 3 is a diagram showing a conventional powder supply device. 1... Reservoir hopper, 2... Powder, 3, 5... Screw feeder, 4... Loosening device, 6... Damper, 7... Air cylinder, 8... Weighing machine, 9...
…Control device.

Claims (1)

[Scope of Claim for Utility Model Registration] In a powder or granule supply device that supplies powder or granules to a weighing machine using a screw feeder, an upstream screw feeder is provided at the upper stage, and the upstream screw feeder is A downstream screw feeder to which powder and granular material is supplied and which has a larger conveyance capacity than the upstream screw feeder is provided at the lower stage, and the layer thickness of the powder and granular material transferred by the downstream screw feeder is controlled. A supply device for powder and granular material, characterized in that it is made thin so that the amount of powder and granular material flowing into a weighing machine is made uniform.