JPH0780181B2 - Granulating method and apparatus for plastics - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for granulating plastics, and more particularly to a new improvement for automatically controlling an optimum pressing pressure of a cutter knife against a die surface by a control device. is there.

[0002]

2. Description of the Related Art As a conventional method of controlling the pressing of a cutter knife of a molten plastics granulating apparatus of this type, it is generally adjusted on-site each time. As a thing, the structure shown in FIG. 3 can be mentioned. That is, what is indicated by reference numeral 1 in FIG. 3 is a granulator, and this granulator 1 has a manifold 2 for circumferentially distributing molten resin extruded from an extruder (not shown), and a manifold 2 for distributing the molten resin. It comprises a die 3 which is attached in close contact with the manifold 2, a cutter case 4 which is attached to the die surface 3a side of the die 3, and a cutter 5 which is provided in the cutter case 4. The die 3 has a disc shape, and a ring-shaped region surrounding the center of the die 3 has a large number of nozzles 6 penetrating in the axial direction.
6 are provided in communication with the resin passage 2a.
One end of the nozzle 6 opens into the resin passage 2a of the manifold 2, and the other end opens into the cutter case 4.

The cutter case 4 is constructed so as to be detachably attached to the surface of the die 3 by a bolt 7. The cutter case 4 is provided with a hot water inlet 8 and a temperature outlet 9 so that the inside of the cutter case 4 is always warm water 4.
It is designed to be filled with a. The cutter 5 has a structure in which a plurality of cutter knives 11, 11, ... Are radially fixed and supported on the outer periphery of the end surface of the cutter holder 10 facing the die 3, and each cutter knife 11 has a die surface of the die 3. 3a, that is, the nozzles 6, 6, ... Are arranged so as to face the surface of the ring-shaped region. A rotational force is transmitted to the cutter holder 10 by a cutter drive shaft 12 arranged on the central axis of the cutter holder 10. The cutter holder 10 is attached to and detached from the cutter drive shaft 12 via a bolt 10a and a key groove 10b. It is provided freely.

At one end of the cutter case 4, a housing 15 having a sleeve 52 that is axially movable via an O-ring 50 and a plurality of packings 51 is attached via a bolt 53. Sleeve 52
The cutter drive shaft 12 is coaxially and rotatably provided in the inside through a pair of shaft sealing devices 54 and a pair of bearings 55. The cutter drive shaft 12 is axially (longitudinal direction) with respect to the sleeve 52. ) Is relatively immovable.

A first cavity 58 and a second cavity 57 are formed between the rear portion 52a of the sleeve 52 and the rear portion 15a of the housing 15, and a first hole 58 is formed in the first cavity chamber 56. Are communicated with each other, and the second void chamber 57 is formed.
A second hole 59 is formed to communicate therewith. The cutter drive shaft 12, the sleeve 52, and the housing 15 constitute a cutter knife axial sliding mechanism 100.

A key 60, which is radially implanted in the rear portion 52a of the sleeve 52, penetrates a through groove 61 formed in the rear portion 15a of the housing 15 and projects to the outside. The detection rod 62a of the detection means 62 formed of a dial gauge or the like provided on the outer surface 15b of the housing 15 contacts. The housing 1
A ring-shaped rear lid 63 is attached to the rear end 15c of the bolt 5 through bolts 64, and a stopper 66 having an operating lever 65 is screwed into a screwing portion 63a formed in the rear lid 63. ing.

The stopper 66 is in contact with an adapter 67 connected to the rear end 52c of the sleeve 52,
By rotating the stopper 66 to move it in the axial direction, the stopper operation in the axial direction of the sleeve 52 can be obtained. Further, a first switching valve 70 connected to a pressure medium source 69 having a pressure medium such as compressed air or pressure oil via a first pressure adjusting valve 68 is connected to the first hole 58, and Second hole 5
A second switching valve 72 is connected to 9 via a second pressure adjusting valve 71. In addition, the first hole 58 and the second hole 59.
A pressure gauge 73 is connected to each of the pressure adjusting valves 68 and 71 in order to monitor the pressure of the pressure medium supplied to.

The conventional plastics granulating apparatus is constructed as described above, and its granulating method will be described below. First, when the second pressure adjusting valve 71 is fully opened, the sleeve 52 moves to the die 3 side in the housing 15 by the action similar to the piston by the pressure medium supplied to the second void chamber 57, and the die surface 3a. A cutter knife 1
1 is pressed, and in this state, the detecting means 62 sets the current state to zero.

When the cutter driving shaft 12 is rotated by a driving means (not shown) in the above-mentioned state, the cutter knife 11 rotates at a high speed, and the molten plastics (not shown) discharged from the nozzle 6 is moved by each cutter knife 11. The pellets that have been finely cut are solidified with hot water or cold water in the cutter case 4, sent together with this hot water or cold water from a hot water outlet 9 to a treatment unit (not shown), and dried to be manufactured as plastics grains. It

[0010]

Since the conventional plastics granulating apparatus is constructed as described above, the following problems exist. That is, when the cutter driving shaft 12 is rotated by the driving means (not shown), a thrust is generated by the rotation of the cutter knife 11, and this thrust increases as the rotation speed of the cutter knife 11 increases, and the thrust rotation speed increases in the normal rotation speed range. Then, it becomes significantly large. This thrust moves the cutter knife 11 in the forward direction and presses it against the die 3, which causes wear and plucking of the cutter knife 11. Therefore, the rotation speed of the cutter drive shaft 12 is detected and the rotation speed signal is detected. First manually based on
It was necessary to adjust the pressure adjusting valve 68 each time to control the pressure medium in the first void chamber 56 to keep the contact state between the cutter knife 11 and the die surface 3a optimal. Further, in this type of granulating apparatus, as shown in FIG. 4, hot water in the tank 110 is supplied to the cutter case 4 by the pump 111, and the plastic pellets cut by the cutter knife 11 are cooled and the dehydrator 112 and the dryer are dried. It is carried to machine 113,
The transport pipe 11 to the dehydrator 112 and the dryer 113
No. 4 is required to have an inclination in order to prevent the pellets from sticking to each other.
The height H is often a meter, and the height H varies depending on the distance to the dehydrator 112 and the dryer 113 and the arrangement, and may be a head pressure of 35 mH ₂ O. Therefore, since the sleeve 52 is pushed by the head pressure of the hot water 4a, it is necessary to manually adjust the pressure adjusting valves 68 and 71. Also, the cutter knife 11 is
It is necessary to move forward and backward, and this is realized by the movement allowance of the first void chamber 56 and the second void chamber 57 of the sleeve 52, but at this time, a force greater than the frictional force is required, and the first pressure regulating valve 6
8 and the setting of the second pressure adjusting valve 71 had to be manually adjusted so as to correspond to a force equal to or greater than this frictional force. In such a state, when the cutter knife 11 needs to operate at a relatively low rotational speed, when the differential pressure between the first pressure adjusting valve 68 and the second pressure adjusting valve 71 exceeding the medium supply pressure source is required. Therefore, it is necessary to reduce the set pressure of the first pressure adjusting valve 68 and increase the differential pressure to cope with the above. Therefore, the first pressure adjusting valve 68 and the second pressure adjusting valve 71 are manually adjusted each time based on the number of revolutions of the cutter knife 11 and the head pressure of the hot water 4a, and the contact state between the cutter knife 11 and the die surface 3a is adjusted. I had to keep it optimal.

The present invention has been made to solve the above problems, and in particular, provides a method and apparatus for granulating plastics in which an optimum pressing pressure is automatically controlled by a control device. The purpose is to do.

[0012]

A plastics granulating apparatus according to the present invention comprises a cutter case filled with warm water,
The molten resin extruded from the die is provided by a cutter knife that is provided on a cutter drive shaft located in a sleeve in the housing through a cutter holder and rotates in water while contacting the die surface along the die surface of the die. In the method of granulating plastics, the plastics granules are obtained by cutting, and the pressing pressure of the cutter knife against the die surface is controlled by a plurality of pressure control valves, in which the cutter drive shaft of the cutter knife is rotated. Number and the head pressure of the hot water of the cutter case containing the cutter knife are taken into the control device, the pressing pressure is controlled via each of the pressure adjusting valves, and the cutter drive shaft is made of an elastic body via the sleeve. To constantly obtain the required pressing pressure even when the maximum pressure of the pressure medium source is low. It is a method.

The plastics granulating apparatus according to the present invention has a cutter holder which is rotationally driven along the die surface of a die in a cutter case filled with warm water, and a cutter holder which is connected to a cutter driving shaft. A molten plastic that is provided with a housing that incorporates the cutter drive shaft that rotationally drives the cutter holder via a sleeve, and obtains plastic grains by cutting the molten resin extruded from the die with the cutter knife. In a granulating apparatus of a nozzle, a first means for supplying a pressure medium to the first and second void chambers formed between the housing and the sleeve that holds the cutter drive shaft coaxially and rotatably in the housing. The first and second pressure regulating valves, the first and second switching valves, the rotational speed of the cutter drive shaft, and the cutter case. A controller for detecting the head pressure of the hot water inside and calculating the pressure of the pressure medium in each of the void chambers, and an elastic body for constantly urging the cutter drive shaft toward the die side via the sleeve. The pressure medium of each pressure chamber and the elastic body control the pressing pressure of the cutter knife against the die surface.

[0014]

In the method and apparatus for granulating plastics according to the present invention, the force of pressing the cutter knife against the die surface is adjusted by adjusting the pressure of the pressure medium supplied into each of the void chambers formed between the sleeve and the housing. Can be adjusted, so that the influence of the thrust generated by the rotation of the cutter drive shaft is calculated and predicted in advance, so that each time the rotation speed of the cutter drive shaft is changed, it is supplied into the void chamber formed between the sleeve and the housing. The pressure of the pressure medium can be automatically adjusted by the control device, and the cutter knife can be pressed against the die surface with an appropriate pressing pressure. Further, when the cutter housing is filled with warm water and different head pressures are generated for each plant, the head pressure is detected or preliminarily calculated and predicted in the space between the sleeve and the housing. The pressure of the pressure medium to be supplied can be automatically adjusted by the control device, and the cutter knife can be pressed against the die surface with an appropriate pressing pressure.
Further, since the elastic body is provided in the void space formed between the sleeve and the housing, even if the maximum pressure of the pressure medium source is low, an appropriate pressing pressure of the cutter knife can be obtained at the desired rotation speed of the cutter knife. As can be obtained, by changing the setting of the pressure of the pressure medium supplied to the cavity chamber required for the forward and backward movement of the cutter drive shaft and the pressure of the pressure medium necessary for pressing the cutter knife, and instructing the output, It is possible to widen the range of the rotational speed of the cutter drive shaft that can appropriately adjust the pressing pressure against the die surface.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a plastics granulating method and apparatus according to the present invention will be described in detail below with reference to the drawings. The same or equivalent parts as those of the conventional example will be described with the same reference numerals. FIG. 1 is a configuration diagram showing an overall configuration of a main part of a plastics granulating apparatus according to the present invention, and FIG. 2 is a characteristic diagram.

In the figure, the reference numeral 1 designates a granulator, which is attached to a manifold 2 connected to an extruder (not shown), and a die 3 which is mounted in a close contact state with the die 3. It is mainly composed of a cutter case 4 attached to the die 3 and a cutter 5 provided in the cutter case 4, and the inside of the cutter case 4 is constantly filled with hot water 4a supplied from the hot water inlet 8 to the hot water outlet 9. The molten plastic extruded from the die 3 in the state of being cut is cut.

The cutter 5 has a structure in which a plurality of cutter knives 11 are radially fixed and supported on the outer circumference of the end face of the die 3 facing the cutter holder 10 and facing the die surface 3a. The cutter holder 10 is mounted via bolts 10a. It is detachably attached to the cutter drive shaft 12. At one end of the cutter case 4, a housing 15 having a sleeve 52 that is axially movably incorporated is fixed bolt 53.
The cutter drive shaft 12 is attached by
It is held so as to be rotatable relative to this sleeve 52.

At the rear part of the sleeve 52, between the rear part of the housing 15 and the first space 56 and the second space 5.
7 is formed, the cutter drive shaft 12 moves in the direction opposite to the die 3 when pressure is applied to the first void chamber 56, and the cutter drive shaft 12 moves in the die 3 direction when pressure is applied to the second void chamber 57. It has a structure.

A first pressure adjusting valve 68 and a first switching valve 70 are connected to the first void chamber 56 via a first hole 58, and a second pressure chamber 68 is connected to a second void chamber 57 via a second hole 59. Pressure control valve 7
1 and the second switching valve 72 are connected to each other, and each pressure medium source 6
The configuration is such that the pressure medium is supplied from 9.

The pressing medium supply device 200 includes the first pressure adjusting valve 68 and the first switching valve 70, the second pressure adjusting valve 71 and the second switching valve 72, the first pressure adjusting valve 68 and the second pressure adjusting valve 68. A control device 201 that outputs a pressure setting signal to the adjusting valve 71 and a signal converter 202 that outputs a rotation speed Nc of the cutter drive shaft 12 (this signal is also replaced by a control signal of a cutter drive motor (not shown)). (Possible) and a pressure transmitter 162 provided in the cutter case 4 for detecting the head pressure Pw of the hot water 4a in the cutter case 4.

Next, in the above-mentioned configuration, the control device 201 of the pressing medium supply device 200 is actually used to
A case where the pressing pressure of the cutter knife 11 against the die surface 3a is controlled to a suitable state will be described. First, the thrust Fs generated by the rotation speed Nc of the cutter 5 is as shown in FIG.
It can be estimated in advance as shown in. Fs = f (Nc) On the other hand, the force Ff required to move the cutter drive shaft 12 to the pushing (advancing) side is set to the second pressure adjusting valve 71 by the control device 201 as the set value Pf, and then pulled ( The force Fb required to move to the (reverse) side is the first pressure adjusting valve 6
8 is set as a set value Pb by the control device 201.

Further, the head pressure Pw of the hot water 4a obtained from the pressure transmitter 162 provided in the cutter case 4 causes a force Fw for moving the sleeve 52 toward the pulling (retracting) side. Therefore, the force (pressing pressure) P with which the cutter knife 11 is pressed against the die surface 3a is calculated by P = Ff + Fs-Fb-Fw-Fr. (However, Fr is the sliding resistance of the sleeve 52.)

Since the thrust Fs is determined by the rotational speed Nc of the cutter drive shaft 12, the desired optimum pressing pressure P can be set in advance by the set pressure of the second pressure adjusting valve 71, and therefore the rotational speed of the cutter 5 is convenient for production. It can be set automatically even when changes occur.

The force Fb required to move to the pulling (retracting) side can be freely set by the first pressure adjusting valve 68.
When the pressure of the pressure medium source 69 is low and the force Ff required to move to the pushing (advancing) side that is equal to or higher than the pressure of the pressure medium source 69 is required, it is necessary to move to the pulling (retracting) side. This effect can be enhanced by reducing the force Fb to be set, and further by providing the elastic body 203 made of a spring or the like so as to act on the push side in the second void chamber 57. In addition,
The elastic body 203 can be provided not only in the second void chamber 57 but also in another place to obtain the same action.

Therefore, the control device 201 adjusts the pressure of the pressure medium supplied into each of the void chambers 56 and 57 formed between the sleeve 52 and the housing 15 so that the cutter knife 11 is moved to the die surface 3a. Since the pressing pressure applied to the cutter can be adjusted freely, the cutter drive shaft 1
By preliminarily calculating and predicting the influence of the thrust force Fs generated by the rotation of 2, the pressure of the pressure medium supplied into each of the void chambers 56 and 57 is automatically set every time the rotation speed Nc of the cutter drive shaft 12 is changed. The cutter knife 11 can be adjusted and pressed against the die surface 3a with an appropriate force.

Further, when the cutter case 4 is filled with the hot water 4a and the head pressure Pw which is different for each plant is generated, the actual head pressure Pw is detected by the control device 201, or the head pressure Pw is calculated and predicted in advance. Each void chamber 56,5
It is possible to automatically control the pressure of the pressure medium supplied into the inside 7 and press the cutter knife 11 against the die surface 3a with an appropriate force.

Further, since the elastic body 203 is provided in the second void chamber 57 or in another portion,
Even if the maximum pressure of the pressure medium source 69 is low, each void chamber 56 required when the cutter drive shaft 12 is moved forward and backward so that an appropriate pressing pressure of the cutter knife 11 can be obtained when the rotational speed Nc of the cutter knife 11 is desired. , 57, and the pressure medium pressure required for pressing the cutter knife is changed by the control device 201 to instruct the output, so that the cutter knife 11 is appropriately pressed against the die surface 3a. The range of the rotation speed Nc of the cutter drive shaft 12 that can be adjusted to a wide range can be widened.

[0028]

Since the method and apparatus for granulating plastics according to the present invention are configured as described above, the following effects can be obtained. (1) Since the cutter medium is pressed against the die surface by the pressure medium and the elastic body, a desired pressing pressure can be obtained even if the maximum pressure of the pressure medium source is low. (2) Even if the number of revolutions of the cutter changes, the supply pressure of the pressure medium can be automatically controlled according to the thrust generated, so the contact state between the cutter knife and the die surface is optimized and Efficient granulation and longer life of cutter knife and die can be achieved. (3) The optimum conditions for the granulation operation can be obtained by actually detecting or calculating the head pressure of hot water in the cutter case depending on the equipment arrangement of each plant. (4) Since the supply pressure of the pressure medium can be freely controlled on the pushing (forward) side and the pulling (backward) side, it is possible to avoid being restricted by the maximum pressure of the pressure medium source. (5) Conventionally, the efficiency of granulation depends largely on the skill of the driver, but since the optimum pressing force can be obtained by calculation, the required skill level can be reduced and the labor shortage can be resolved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall configuration of a main part of a plastics granulating apparatus according to the present invention.

FIG. 2 is a characteristic diagram showing a relationship between rotation speed and thrust.

FIG. 3 is a configuration diagram showing a conventional plastics granulating apparatus.

FIG. 4 is a configuration diagram showing a conventional plastics granulating apparatus.

[Explanation of symbols]

 3 dies 3a dies surface 4 cutter case 4a hot water 11 cutter knife 12 cutter drive shaft 15 housing Nc rotation speed 52 sleeve 56 first void chamber 57 second void chamber 68 first pressure adjusting valve 69 pressure medium source 70 first switching valve 71 Second pressure adjusting valve 72 Second switching valve Pw Head pressure 201 Control device 203 Elastic body

(72) Inventor Takaaki Okita 1-6-1, Funakoshi-minami, Aki-ku, Hiroshima City, Hiroshima Prefecture, Japan Steel Works, Ltd. No. 1 in Japan Steel Works, Ltd. (56) References JP-A-4-25409 (JP, A)

Claims (3)

[Claims] 1. A cutter drive shaft (12) located in a sleeve (52) in a housing (15) provided in a cutter case (4) filled with warm water (4a) via a cutter holder (10). Along with the die surface (3a) of the die (3) together with the die surface (3
With a cutter knife (11) rotating in water while contacting with a), a plastics grain is obtained by cutting the molten resin extruded from the die (3), and the cutter knife for the die surface (3a). In the granulation method of plastics, the pressing pressure of (11) is controlled by a plurality of pressure control valves (68, 71), the rotational speed (Nc) of the cutter drive shaft (12) of the cutter knife (11). And the cutter knife (11)
Head pressure of hot water (4a) in the cutter case (4)
(Pw) is taken into the control device (201), and each pressure adjusting valve (6
8, 71) to control the pressing pressure, and the sleeve (52) to connect the cutter drive shaft (12) to the elastic body (2).
A method for granulating plastics, characterized in that it is constantly energized by 03) to obtain the required pressing pressure even when the maximum pressure of the pressure medium source (69) is low. 2. A cutter case (4) filled with warm water (4a) has a cutter knife (11) which is rotationally driven along a die surface (3a) of a die (3) and a cutter drive shaft (12). ) Connected to the cutter holder (10) and a housing (15) having the cutter drive shaft (12) for rotationally driving the cutter holder (10) built in via a sleeve (52), and the die (3)
In a granulating apparatus for molten plastics, which is obtained by cutting the molten resin extruded from the cutter knife (11) to obtain plastics particles, the cutter drive shaft (12) in the housing (15). First and second pressures for supplying a pressure medium to the first and second void chambers (56, 57) formed between the sleeve (52) coaxially and rotatably held and the housing (15) Regulator valve (68,71)
And the first and second switching valves (70, 72) and the cutter drive shaft (1
Rotation speed (Nc) of 2) and hot water (4a) in the cutter case (4)
A controller (201) that detects the head pressure (Pw) and calculates the pressure of the pressure medium in each of the void chambers (56, 57), and the cutter drive shaft (12) via the sleeve (52). The dice (3)
The elastic body (203) for constantly urging the side, and the pressure of the pressure medium in each of the void chambers (56, 57) and the elastic body (203)
The molten plastics granulating apparatus is characterized in that the pressing pressure of the cutter knife (11) against the die surface (3a) is controlled by the above. 3. The elastic body (203) is provided in the housing (1).
Void chamber (56 or 57) formed between 5) and the sleeve (52)
The granulating apparatus for molten plastics according to claim 2, wherein the granulating apparatus for molten plastics is provided in the.