JPH02253891A - Device for removing colored grain from resin pellet - Google Patents

Abstract

PURPOSE:To obtain the device for removing colored grains from resin pellets without generating the screening defect by static electricity by bringing the air moistened to the extent of not dew-condensing onto raw material surfaces into contact with raw materials transported from a supply hopper to the terminal part of a transporting belt. CONSTITUTION:The pellets flowing down in the bottom end part of the supply hopper 9 are transported to the terminal part of the transporting belt 2 by receiving the wet air which has the moisture content below the satd. moisture and is sent from a wet wind generator 32. These pellets fall between a pair of optical cases 11 and 12. If, for example, the defective pellet with its one surface blacked by carbon comes to a detecting line P, any of photodetecting sensors 17 of photodetecting parts 13 to 15 facing this surface detects the difference between the light quantity of backgrounds 18 to 19 adjusted to nearly the same light quantity as the light quantity of the normal pellet and the light quantity of the defective surface and an ejector 24 corresponding to the position of the sensor 17 operates with a slight delay to flow-off this pellet into a defective pellet discharging trough 27.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin pellet colored particle removal device for removing colored particles contained in resin pellets that are raw materials for nylon products and the like.

[Technical background]

Extremely small amounts of colored particles (
Conventionally, in order to remove 0.0fl1%), sorting was done manually, which was inefficient.

Therefore, in order to remove colored defective products with high efficiency, the present inventor created an apparatus for removing colored particles from resin pellets, which includes a means for conveying raw material pellets, a means for detecting defective products, and a means for removing defective products.

[Problem that the invention seeks to solve]

Incidentally, the resin pellets used as raw materials are rice grain-shaped and easily become electrically charged due to particle friction. Therefore, an attractive force acts between the conveyance means and the pellets, as well as between the pellets, and the conveyance means causes a defective product detection means and then a defective product removal means. There was a problem in that the conveyance to the pellets was not carried out smoothly and the pellets adhered to each other, resulting in good products being removed along with defective products, resulting in a decrease in sorting accuracy. This becomes noticeable when the humidity in the atmosphere is low and static electricity is likely to occur.

In view of these points, the technical object of the present invention is to provide an apparatus for removing colored particles from resin pellets that does not cause sorting defects due to static electricity.

[Means for solving problems]

In order to solve the above-mentioned problems, the resin pellet discoloration removal apparatus of the present invention has a supply hopper connected to the starting end of an endless belt for conveying raw material that is horizontally and rotatably suspended, and a supply hopper is connected to the ending end of the endless belt for conveying raw materials. In an apparatus for removing colored grains from a resin pellet, which is provided with a defective product detection means and an ejector for removing the defective product, a. The objects to be sorted are disposed in a band-like manner from the terminal end of the conveyor belt, and each optical case is provided with a background facing the light-receiving section.

Furthermore, a humidifying means is provided for bringing humidified air into contact with the raw material conveyed from the supply hopper to the terminal end of the conveyor belt to an extent that does not cause dew condensation on the surface of the raw material.

This technical measure was taken.

As a humidifying means, one of a pair of porous walls formed near the lower end of the supply hopper is connected to one end of the exhaust pipe, and the other is connected to one end of the blast pipe, and the other end of the blast pipe is connected to the humid air. It is effective to connect the generator, or provide a cover surrounding the conveyor belt, in which the
An evaporating dish filled with water and a humidity sensor may be provided, as well as a heater for heating the evaporating dish, and a switch may be provided to turn on the heater when the humidity sensor detects a humidity below a certain level.

[Action and effect]

The raw material pellets put into the supply hopper fall onto the endless belt and are transported to the end of the belt.
For the pellet from the supply hopper to the end of the belt,
The humidifying means brings into contact humidified air that does not cause dew condensation, and works to dissipate static electricity caused by the friction of the pellet. The pellets that have not accumulated static electricity are emitted from the end of the endless belt towards the space between the pair of optical cases, receive the projected light from the light source, and the light receiving section detects the light intensity of each pellet, and based on this light intensity, an error is detected. Identify non-defective products and remove them with an ejector.

In this way, by providing a humidifying means, it is possible to release the frictional electricity generated in the pellets, eliminating the adhesion of pellets to each other and the attraction between the pellets and the conveyor belt. This improves sorting accuracy by eliminating the need to remove non-defective products at the same time.

As a humidifying means, a pair of porous walls are formed near the lower end of the supply hopper, and by supplying humidified air from a humid air generator to these porous walls, the pellets flowing down inside the hopper are exposed to humidified air and static electricity is generated. escape.

In addition, if the endless belt is surrounded by a cover as a humidifying means and an evaporating dish and a hygrometer are installed inside the cover, the pellets conveyed by the endless belt can be placed in a humidified atmosphere up to just before the detection part. , it is possible to prevent harmful effects caused by static electricity.

Furthermore, by interlocking the humidity sensor and the heater switch of the evaporating dish, it is possible to maintain a constant humidity inside the cover.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the present invention will be described based on FIGS. 1 to 4. In FIG. 1, a conveyor belt 2 is rotatably mounted horizontally in the vicinity of the center of an approximately rectangular parallelepiped machine frame 1 placed horizontally. That is, the endless conveyor belt 2, which is passed between rollers 3 and 4 that are horizontally arranged in parallel, is rotated at a constant speed by a motor 5 that is connected to the rollers 3 by a belt or the like. Furthermore, side walls 7 are fixedly provided on both sides of the upper surface (transport surface) of the conveyor belt 2, which are perpendicular to the conveyance direction, to prevent the pellets from falling off during conveyance.

The starting end side of the conveyor belt 2 faces the machine end of a vibrating feed gutter 8 serving as an appropriate amount feeding device. The lower end of the supply hopper 9 faces above the vibrating supply gutter 8 , and the bottom surface of the vibrating feed gutter 8 is supported by the vibration device 10 .

Further, a pair of opposing porous portions 30.30 are formed near the lower end of the supply hopper 9, and one porous portion 30.
is connected to a humid air generator 32 via a blow pipe 31, and the other porous portion 30 is connected to a louver 34 provided in the machine frame 1 via an exhaust pipe 33. The humid air generator 32 includes a nebulizer 34 and a fan 35, and may be equipped with a heater to generate warm and humid air.

On the other hand, defective product detection means for detecting colored grains is provided midway along the falling path of the pellets released from the terminal end of the conveyor belt 2. That is, a pair of optical cases 11 whose length is approximately the same as the width of the conveyor belt 2 are placed on both sides of the falling path.
．． 12 are provided facing each other, a light receiving section 13 and a light receiving section 14 are arranged side by side in the optical case 11 facing the falling path, and a light receiving section 15 is provided inside the optical case 12 facing the falling path. . Each of the light receiving sections 13 to 15 is provided with one optical system (which may consist of a plurality of lenses) 16, and five light receiving sensors 17a to 17e each consisting of a photodiode array or the like are provided in a sensor box behind the optical system 16. A background 18 facing the light receiving section 15 within the optical case 12 is provided in the optical case 11, and the light receiving sections 13 and 14 within the optical case 11 are arranged so that they intersect with each other at the detection line P of the pellet on the falling path. , light receiving section 1
A background 19 for 3 and a background 20 for the light receiving section 14 are provided in the optical case 12. In other words,
The light receiving section 13 and the light receiving section 14 are provided facing inward to each other, and the distances from the detection line P to each of the light receiving sections 13 to 15 are equal distances, and each optical system 16 has a belet on the detection line P that is connected to the optical system. It is provided so that the image is formed on the light receiving sensors 17a to 17d through a slit (not shown) in front of the light receiving sensor 16.

Further, each of the light receiving sections 13 to 15 is arranged in succession in the width direction of the conveyor belt 2 within each optical case 11.12, and the light receiving sensors 17a to 17e of each of the light receiving sections 13 to 15 are
As a result, almost the entire circumferential surface of all diced vegetables on the detection line P is captured (see FIG. 4).

Fluorescent tubes 21A-21E are arranged within each optical case 11.12. That is, inside the optical case 11 is a fluorescent tube 21A that illuminates the vicinity of the detection line P through the transparent plate 22 of the optical case 11.

21C are provided along the light receiving sections 13 and 14, respectively, and a fluorescent tube 2 which also serves as a light source for the background 18 is provided.
1B, and a transparent plate 2 is provided inside the optical case 12.
Fluorescent tubes 21D and 21E are provided with the light receiving section 15 in between and serve as a light source for illuminating the vicinity of the detection line P through the fluorescent tube 3 and as a light source for the background 19.20.

Each of the backgrounds 18 to 2o is rotatably provided by a servo motor or the like (not shown) via a microcomputer so that the angle with respect to the fluorescent tubes 21B, 21D, and 21H provided nearby can be changed. The brightness of background rounds 18 to 20 is automatically adjusted according to the object to be sorted (vellet).

Each light receiving section 13~ is located near the fall path below the detection line P.
Ejectors 24 are connected to correspond to the 15 light receiving sensors 17a to 17e. The ejector 24 is connected to an air compressor (not shown), and corresponds to each light receiving sensor 17a to 17e and the light receiving sensor 17a to 17e so that high pressure air is ejected by a solenoid valve 25 provided in each ejector 24. The operating circuit of the electromagnetic valve 25 in the ejector 24 is electrically connected. Further, a good product discharge gutter 26 is provided below the ejector 24, that is, on the falling path, and a defective product discharge gutter 27 is provided on one side of the good product discharge gutter 26 to receive the defective products blown away by the ejector 24. A regulating valve 28 is provided at the branch portion.

Next, specific operations in the above embodiment will be explained. When raw material pellets are put into the supply hopper 9 and the vibrating device 10 and motor 6 are started, the pellets are supplied in appropriate amounts onto the conveyor belt 2 by the vibrating supply gutter 8. The pellets flowing down are exposed to the humid air blown from the humid air generator 32. The amount of moisture contained in this humid air is set to be less than saturated steam, and to the extent that no dew condensation occurs on the pellet surface or the wall surface of the supply hopper 9. The pellets supplied onto the conveyor belt 2 are conveyed to the terminal end of the conveyor belt 2 in a thin layered state. The conveyor belt 2 is driven at approximately 1.5ffi/sec, and the pellets released from the end of the conveyance fall between a pair of optical cases 11 and 12, as shown in the figure.

The pellets falling between the pair of optical cases 11 and 12 are oriented in various directions, but when these pellets pass the detection line P, the light receiving sections 13 to 15 detect defective spots on the entire surface. In other words, the light receiving sections 13.14 and 15 sandwich the strip-shaped falling path, and since the light receiving sections 13.14 are shifted in the flow direction of the pellets and are provided toward the detection line P, pellets can be detected from three directions. Almost the entire surface is captured, and on the other hand, the light receiving parts 13 to 1
Fluorescent tubes 21A to 21E are arranged near each of 5.
This causes the entire surface of the pellet to be projected. Each of the light receiving sensors 17a to 17e of the light receiving sections 13 to 15 receives the amount of light from the opposing backgrounds 18 to 20, and for example, a defective pellet whose one surface is blackened with carbon is detected. When reaching the detection line P, one of the light receiving sensors 17a to 17e of the light receiving sections 13 to 15 facing this surface detects the light intensity of the backgrounds 18 to 19, which has been adjusted to approximately the same light intensity as the normal pellet. Detects the difference in light intensity with the defective surface. This difference is electrically converted and compared with a preset threshold value. If the signal (voltage) is larger than the threshold value, the pellet is determined to be defective, and the position of the light receiving sensors 17a to 17e is determined. The ejector 24 corresponding to the ejector 24 operates with a slight delay (the time required for the pellet on the detection line P to fall to the injection port of the ejector 24 is delayed), and the pellet is sprayed into the defective product discharge gutter 27. .

The light intensity of the backgrounds 18 to 20 can be adjusted by changing the angle of the backgrounds 18 to 20 and raising or lowering the light intensity using a microcomputer or the like to the light receiving sensors 17a to 17.
The brightness that makes the output waveform of e is the smallest is selected, and the light intensity of backgrounds 18 to 20 is always made to match the light intensity of normal pellets, which account for the majority of the raw material pellets.

Wipers 29 may be provided on the opposing transparent walls 22 and 23 of the optical case 11 and 12 to remove dust and the like adhering to the transparent walls 22 and 23. Furthermore, it goes without saying that the present invention is not limited to the above-mentioned embodiments, and can also be implemented with a so-called bichromatic type, in which the amount of light divided into a plurality of wavelength bands is received by separate light receiving sensors.

Next, another embodiment of the humidifying means will be described based on FIG. An evaporation plate 36 is provided at the bottom of a cover 35 that surrounds the conveyor belt 2 except for a portion of the starting end, a portion of the ending end, and the exhaust port 40, and a humidity sensor 37 is provided near the top.
to be placed. A heater 3 that heats the evaporating dish 35
8 and a switch 39 for the heater 38, and the switch 39 and the humidity sensor 37 are electrically connected via a reference humidity setting device (not shown).

As a result, the reference humidity at which the humidity sensor 37 operates is set to 9.
Assuming 5%, when the atmosphere inside the cover 35 falls below 95%, the humidity sensor 37 is activated and the switch 39 is closed.
The heater 38 becomes red hot and evaporates the water in the steamer 36,
It can maintain a constant humidity level.

[Brief explanation of drawings]

Fig. 1 is a side view and central vertical sectional view, Fig. 2 is a partially enlarged view of Fig. 1, Fig. 3 is a perspective view showing the relationship between the falling objects to be sorted and a pair of optical cases, and Fig. 4 is FIG. 5, an explanatory diagram of the light receiving section, is a sectional view showing another embodiment. 1... Machine frame, 2... Conveyor belt, 3... Roller 4... Roller, 5... Motor, 7... Side wall,
8... Vibrating supply gutter, 9... Supply hopper, 10...
・Vibration device, 11.12...Optical case, 13-15
... Light receiving section, 16... Optical system, 17a to 17e...
・Light receiving sensor, 18, 19.20... Background, 21A to 21E... Fluorescent tube, 22.23...
Transparent plate, 24... Ejector, 25... Solenoid valve,
26... Good product discharge gutter, 27... Defective product discharge gutter, 28
... Regulating valve, 29... Wiper, 30... Porous portion, 31... Air pipe, 32... Moist air generator, 33...
...Exhaust pipe, 34...Gallery, 35...Cover, 3
6... Evaporation dish, 37... Humidity sensor, 38... Converter, 39... Switch, 40... Exhaust port.

Claims (1)

[Scope of Claims] 1) A supply hopper is connected to the starting end of an endless belt for conveying raw materials that is horizontally and rotatably suspended, and a means for detecting defective products and a means for removing the defective products are provided at the end thereof. In the apparatus for removing colored particles from resin pellets, the defective product detection means includes an optical case equipped with a light receiving section having a plurality of light receiving sensors in a direction transverse to one optical system and a light source; The objects to be sorted, which are discharged in a strip form from the end of the endless belt, are placed opposite to each other, and each optical case is provided with a background facing the light receiving section, and further, the material is transported from the supply hopper to the end of the endless belt. 1. An apparatus for removing colored particles from resin pellets, characterized in that a humidifying means is provided for bringing humidified air into contact with the raw material to an extent that does not cause dew condensation on the surface of the raw material. 2) The humidifying means connects one of a pair of porous walls formed near the lower end of the supply hopper to one end of the exhaust pipe and the other to one end of the blower pipe, and connects the other end of the blower pipe to one end of the blower pipe. The apparatus for removing colored particles from resin pellets according to claim 1, which is connected to a wet air generator. 3) The humidifying means is provided with a cover that surrounds the endless belt for conveyance, and within this cover, an evaporating dish filled with water and a humidity sensor are provided, as well as a heater that heats the evaporating dish, and the humidity sensor is The apparatus for removing colored particles from resin pellets according to claim 1, further comprising a switch that turns on the heater when the humidity is detected to be below a certain level.