JPH10249851A - Raw material supplying apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a raw material supplying apparatus for holding a mixture ratio of powder-like raw material to air volume change in a duct constant. SOLUTION: The raw material supplying apparatus comprises a pigment tank 8 and a base material tank 5 arranged in a duct 1 to mix powder-like materials and to supply the mixture to a hopper 2 of a downstream side via an air flow. A bypass pipe 10 is provided between an upper space of the tank 8 and an outlet side of a belonging metering unit 9, and an air volume sensor 11 is provided at a part of the duct 1 of an upstream of the tank 5 of the most upstream. A control means 15 for the metering unit to control output rates of the metering units 6, 9 so that the mixture ratio is held constant in response to a decrease of a detection signal level of the sensor from a standard detection signal level is belonged thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of raw material tanks each having a measuring device attached to an upstream side of a duct in which an air flow is generated, and each of powdered raw materials having a delivery amount set by the measuring device. The present invention relates to a raw material supply device that is mixed at a predetermined mixing ratio in a process of being conveyed in a duct and supplied to a downstream hopper.

[0002]

2. Description of the Related Art As a raw material supply apparatus of this kind, for example, an injection molding machine is well known. A base material tank is provided relatively upstream of a duct, and a pigment tank is provided downstream of the duct. The base material and the pigment are delivered and mixed at a predetermined delivery rate from the device and supplied to the hopper.

[0003]

When the air flow in the duct changes due to clogging of the filter or the like in such an apparatus, the conveying capacity of the base material having a large amount of delivery is relatively reduced, and the molded product is reduced. Is caused. In addition, when the duct becomes slightly clogged with the base material, if an airflow is generated by suction by the blower on the downstream side, the outlet side of the measuring device of the pigment tank on the downstream side has a large negative pressure, and the pressure exceeds the set delivery amount. There is a problem that the pigment is sucked out. Therefore, it is necessary to clean the inside of the duct or the filter portion at such a frequency that the mixing ratio is not affected.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a raw material supply apparatus capable of maintaining a constant mixing ratio of powdery raw materials with respect to a change in air flow in a duct.

[0005]

According to the present invention, in order to achieve this object, according to the present invention, a plurality of raw material tanks each having a measuring device attached to a duct are arranged, and a delivery set by the measuring device. In the raw material supply device in which the amount of each powdery raw material is mixed at a predetermined mixing ratio in the process of being conveyed by the airflow in the duct and supplied to the downstream hopper, the upper space portion of the raw material tank A bypass pipe is provided between the outlet sides of the associated measuring devices, and an air flow sensor is provided in a duct portion upstream of the most upstream raw material tank, and the detection signal level of the air flow sensor is reduced from the standard detection signal level. And a control means for the weighing device for controlling the output rate of each weighing device so that the mixing ratio is kept constant.

In response to a decrease in the detection signal level of the air flow sensor, that is, a decrease in the carrying capacity of the duct, the base material and the pigment are delivered at a delivery rate capable of reliably transporting the raw material and maintaining a constant mixing ratio. . The bypass pipe suppresses the generation of a pressure difference between the inlet side and the outlet side of the raw material tank, and thus prevents the raw material from being sucked at a set delivery rate or more due to a relative pressure drop on the outlet side. .

According to the first aspect of the present invention, in order to suppress a large change in the mixing ratio caused by a slight change in the amount of the raw material having a small mixing ratio, the most upstream raw material tank is required to be a weight mixing type. In addition to sending out the raw material occupying 90% or more in proportion, a fine adjustment air flow sensor is provided in a branching duct interposed between the measuring device and the duct belonging to one or more small amount raw material tanks other than the raw material tank. When the control signal for the device is higher than the detection signal level following the detection signal level of the air flow sensor in the upstream duct portion when the detection signal level of the fine adjustment air flow sensor is higher than the detection signal level that follows the detection signal level, It is characterized in that the feed rate of the metering device for the small amount material tank is finely adjusted.

When the detection signal level of the fine-adjustment air flow sensor becomes larger than the detection signal level that normally follows, the transmission rate of the associated metering device is adjusted according to the deviation so that the actual transmission rate does not increase due to the air flow. Fine-tuned.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A raw material supply apparatus for an injection molding machine according to an embodiment of the present invention will be described with reference to FIG. Numeral 1 is a duct for carrying powder in an air flow, provided with a blower 3 on the downstream side, and a filter 1 mounted on the upstream end.
By aspirating through a, an airflow is created. A hopper 2 for supplying a raw material through an outlet 2b to an injection molding machine is provided on the way, and a filter 2 provided at an upper end thereof is provided.
The raw material stays in the hopper 2 by being sucked through the a.

A duct 1 is provided with a base material tank 5 storing a base material and a pigment tank 8 storing a pigment. At the bottom of the base material tank 5, a weighing device 6 provided with a screw rotated by a motor 6a is provided, and is connected to the duct 1 through an outlet chamber 6b and a branch duct 5a. At the bottom of the pigment tank 8, there is provided a metering device 9 having a screw which is driven to rotate by a motor 9a, and is connected to the duct 1 through an outlet chamber 9b and a branch duct 8a.

The metering device 9 is set so as to send out the pigment to the metering device 6 at a weight ratio of, for example, about 5% of the base material. The pigment tank 8 is arranged on the downstream side of the base material tank 5 so as to suppress the influence of a change in the air volume due to the relatively large supply amount of the base material.

Although such an apparatus itself is well known, an air flow sensor 11 for detecting the air flow of the air flow in the duct 1 is disposed in the duct portion upstream of the branch duct 5a according to the present invention. A bypass pipe 10 is attached between the space region at the upper end of the raw material tank 8 and the outlet chamber 9b, and an air flow sensor 13 is provided in the branch duct 8a interposed between the bypass pipe 10 and the duct 1. Further, the detection signals of these air flow sensors are input and the motor drive circuit 6
Control means 15 for a weighing device for controlling a rotation speed and an operation time for defining a delivery rate of the motors 6a and 9a through c and 9c is attached.

When the raw material is transported in the air stream, the base material stays in the duct region particularly below the branch duct 5a for the base material, which has a large supply amount, or the filters 1a and 2a are clogged and the inside of the duct 1 is increased. When the air volume is reduced, the transport amount of the base material is reduced, and the mixing ratio is changed. In addition, depending on the state of stagnation of the raw material or the clogging of the filter 1a, the airflow of the airflow of the branch duct 8a through which the pigment tank 8 is ventilated does not follow the standard level decrease, and is accompanied by a deviation in the plus direction. In some cases, the transmission rate depending on the rotation speed of the motor may be actually increased. Therefore, the control means 15
Indicates that the rotation speed data of the motors 6a and 9a corresponding to the decrease in the detection signal level of the air flow sensor 11 which has been tested in advance, and the detection signal level of the air flow sensor 13 normally follow the decrease in the detection signal level of the air flow sensor 11. Table 15a in which the rotation speed data of the motor 9a corresponding to the deviation and the operation time data of the motors 6a and 9a for keeping the transmission amount constant corresponding to the decrease of the transmission rate are registered. And a clock 15b for measuring a transmission cycle and a transmission time, and control signals for the motors 6a and 9a based on the registered data and the clock signal in the table 15a in response to the detection signal levels of the air volume sensors 11 and 13. And a control signal generator 15c.

As a result, the control means 15 periodically operates the motors 6a and 9a,
In response to the detection signal level of No. 13, the rotation speed and operation time of the motors 6a and 9a are controlled in an open loop by referring to the registered data of the table 15a.

The operation of the raw material supply apparatus thus configured is as follows. Normally, in accordance with the supply amount of the hopper 2 to the injection molding machine, the control means 15 causes the base material and the pigment to be periodically delivered at a standard delivery rate for a standard delivery time. When the detection signal level of the air flow sensor 11 is reduced, the rotation speed of the motor 6a is reduced so that the base material does not stay or clog, and the motor 9a is controlled so as to ensure a predetermined mixing ratio. The rotation speed is also reduced. In response to such a decrease in the delivery rate of the base material and the pigment, the delivery time of the raw material is controlled to be longer.

During this time, in the raw material tank 8, there is no pressure difference between the inlet side and the outlet side. Therefore, the outlet side is set to have a relatively lower pressure due to the fluctuation of the base material conveyance state on the upstream side. It is avoided that the pigment is sucked out above the delivery rate. If the amount of air in the branch duct of the downstream pigment tank 8 is deviated on the plus side to an extent that affects the delivery rate due to the state of stagnation or clogging of the raw material, it follows the decrease in the detection signal level of the air volume sensor 11. Airflow sensor 1 larger than
3, the rotation speed of the motor 9a is further finely adjusted so as to secure a predetermined mixing ratio.

In the above-described embodiment, even if the air flow rate sensor 13 for the pigment is not provided, the delivery ratio of both is adjusted according to the change in the air flow of the duct, and the mixing ratio is kept constant. It is possible. Even when a raw material tank is further added, similarly, a dedicated air volume sensor can be provided in the branch duct, and the rotation speed of each of the motors can be finely adjusted so as to correspond to the amount of the base material to be delivered.

[0018]

According to the first aspect of the present invention, the delivery ratio of a plurality of types of raw materials is adjusted in accordance with a change in the amount of airflow generated in the duct, so that the mixing ratio is reliably maintained until the next cleaning. The powdered raw material is supplied to a hopper. In other words, the frequency of cleaning can be reduced. Further, by providing the bypass pipe, it is possible to prevent the delivery rate from becoming larger than the set value due to the negative pressure caused by the suction when the transport state changes or clogging occurs on the upstream side.

According to the second aspect of the present invention, a phenomenon in which the mixing ratio is largely changed by a small change in the amount of delivery caused by a relatively small amount of the raw material tank on the downstream side is avoided. According to the third aspect of the present invention, the feed time is adjusted according to the change in the feed rate, so that when the raw material is periodically supplied, the supply amount is kept constant each time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a raw material supply device according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Duct 2 Hopper 3 Blower 5 Base material tank 6, 9 Measuring device 8 Pigment tank 10 Bypass pipe 11, 13 Air volume sensor

Claims (3)

[Claims] 1. A plurality of raw material tanks each having a measuring device attached to a duct are arranged, and a predetermined amount of powdery raw material of a delivery amount set by the measuring device is conveyed by an air flow in the duct. In a raw material supply device that is mixed at a mixing ratio and supplied to a downstream hopper, a bypass pipe is provided between an upper space portion of a raw material tank and an outlet side of an associated measuring device, and the most upstream raw material is provided. An air flow sensor is provided in a duct portion upstream of the tank, and as the detection signal level of the air flow sensor decreases from the standard detection signal level, the mixing ratio of the output rate of each of the measuring devices is kept constant. Raw material supply device having a control means for a weighing device, which is controlled as described above. 2. The most upstream raw material tank has a weight mixing ratio of 9%.
A raw material occupying 0% or more, and a fine adjustment air flow sensor provided in a weighing device belonging to one or more small amount raw material tanks other than the raw material tank and a branch duct interposed between the ducts; Control means, the detection signal level of the fine-adjustment air flow sensor is higher than the detection signal level that follows the detection signal level of the air flow sensor in the upstream duct portion,
2. The raw material supply device according to claim 1, wherein the feed rate of the small amount raw material tank from the measuring device is finely adjusted according to a deviation from the following detection signal level. 3. A control device for a weighing device, in addition to controlling a delivery rate, controls a delivery time according to a decrease in the delivery rate so as to maintain a constant supply amount of a raw material supplied to a hopper. The raw material supply device according to claim 1, wherein the raw material supply device is configured. It is characterized by the following.