JP2825448B2 - Plastics granulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the granulation of plastics, and more particularly to a novel improvement for achieving a long life of a cutter knife whose pressing force is adjusted by a pressure medium.

[0002]

2. Description of the Related Art There have been various types of plastics granulators of this type which have been used in the past. Among them, a typical configuration will be described with reference to FIG.
No. 5409 can be cited. In FIG. 3, reference numeral 1 denotes a granulator, and the granulator 1 is attached in a state in which the molten resin extruded from an extruder (not shown) is closely attached to a manifold 2 which distributes the molten resin in a circumferential direction. The die 3 is fixed to the die surface 3a side via a cutter case 4. The die 3 has a disk shape, and a ring-shaped region surrounding the center thereof is provided with a large number of nozzles 6, 6,. One end of the nozzle 6 opens into the ring-shaped resin passage 2 a of the manifold 2, and the other end opens into the cutter case 4.

One side of the cutter case 4 is detachably fixed to the surface 3a of the die 3 by bolts 7 and the granulator 1 is fixed to the other side by bolts 53. The cutter case 4 is provided with a cooling water inlet 8 at a lower portion and a cooling water outlet 9 at an upper portion, so that the inside of the cutter case 4 is always filled with warm water.

In the granulator 1, a sleeve 52 is incorporated in the housing 15 via an O-ring 50 and a plurality of packings 51 so as to be movable in the axial direction by a predetermined distance. The cutter drive shaft 12 is coaxially rotatable via the shaft sealing device 54 and a pair of bearings 55 and is held immovable relative to the sleeve 52 in the axial direction (longitudinal direction). The cutter drive shaft 12 is provided with a bolt 1 at the tip protruding into the cutter case 4.
The cutter holder 10 rotates with the cutter drive shaft 12 via the key 10a and the key 10b and is detachably held.
A drive device (not shown) is connected to the rear end via a shaft joint (not shown) that can slide in the axial direction. A plurality of cutter knives 11, 11,... Are radially fixed and held on the end face of the cutter holder 10 facing the die 3, and each of the cutter knives 11 is attached to the die surface 3 of the die 3.
a, that is, the surface of the ring-shaped region where the nozzles 6, 6, ... are provided. The sleeve 52 forms a piston cylinder together with a rear lid 63 between the rear part 52a and the rear part 15a of the housing 15 using the rear part 52a as a piston.
The first gap chamber 56 formed on both sides of the first gap chamber 56 is formed with a first hole 58, and the second gap chamber 57 is formed with a second hole 59. That is, the cutter driving shaft 12, the sleeve 52 and the housing 15 constitute an axial movement mechanism 100 of the cutter knife 11. Rear part 52a of the sleeve 52
A key 60 implanted in the radial direction projects outside through a through groove 61 formed in the rear portion 15a of the housing 15. The key 60 is provided on the outer surface 15b of the housing 15. The detection rod 62a of the detection means 62 formed of a dial gauge or the like is in contact.

[0005] The rear end 15c of the housing 15 has the ring-shaped rear lid 63 attached thereto via bolts 64, and a threaded portion 63a formed on the inner diameter of the rear lid 63.
Is screwed with a stopper 66 having an operation lever 65. The stopper 66 is rotated so as to move in the axial direction, so that the sleeve 52 is moved at a predetermined position.
The stopper 67 is configured to come into contact with the adapter 67 coupled to the rear end 52c to obtain a stopper operation in the axial direction. Further, the first hole 58 is connected to a pressure medium source 69 having a pressure medium such as compressed air or pressure oil via a first switching valve 70 and a first pressure regulating valve 68, and 59 is connected to the pressure medium source 69 via a second switching valve 72 and a second pressure regulating valve 71. In order to monitor the pressure of the pressure medium supplied to the first hole 58 and the second hole 59, each of the pressure regulating valves 6
A pressure gauge 73 is connected to 8,71.

[0006] The conventional plastics granulator is configured as described above, and the granulating method will be described below. First, when the second switching valve 72 is switched to the supply side and the first switching valve 70 is switched to the discharge side, the sleeve 52
The inside of the housing 15 is moved toward the die 3 by the same action as the piston by the pressure medium supplied to the gap chamber 57, and the cutter knife 11 is pressed against the die surface 3a.
In this state, the state at that time is set to zero by the detecting means 62. When the cutter driving shaft 12 is rotated by a driving device (not shown) in the above-described state, the cutter knife 11 rotates at a high speed, and the molten plastics (not shown) discharged from the nozzle 6 is cut into granules by each cutter knife 11. The cut and pellets are solidified with cooling water supplied from the cooling water inlet 8 into the cutter case 4 and sent to a processing unit (not shown) from the cooling water outlet 9 together with the cooling water.
It is dried and commercialized.

When the cutter knife 11 rotates in the water, a thrust (forward thrust) directed toward the dice 3 is generated.
This thrust changes in proportion to the number of rotations of the cutter knife 11, but becomes extremely large in a normal high-speed rotation range. In particular, the large-capacity granulator 1 used recently has a remarkable tendency to operate at high speed, and the generation of this thrust causes the die surface 3a of the cutter knife 11 to be driven.
, And the cutter knife 11 is greatly worn. Therefore, with respect to the forward thrust caused by the rotation of the cutter knife 11, the first switching valve 70 is switched to the supply side, the pressure medium is supplied to the first gap chamber 56, and the sleeve 5
2 is applied with a force in the direction of retreating against the thrust, thereby canceling most of the forward thrust. That is, the setting of the first pressure regulating valve 68 is set higher than the setting of the second pressure regulating valve 71, most of the thrust is canceled, and the cutter knife 11 causes the die surface 3a to move with the desired force by the remaining forward thrust. Each pressure regulating valve 68, 71 is set so as to be pressed. By the above operation, the cutter knife 11 is constantly pressed against the die surface 3a with a desired weak pressing force and rotates to cut the molten plastic.

Further, the wear state of the cutter knife 11 can be observed from the outside of the apparatus by reading the scale of the detecting means 62.

[0009]

The conventional plastics granulating apparatus has the following problems because it is configured as described above. That is, in the above-described conventional configuration, when the molten resin coming out of the die is cut, the edge of the cutter knife is worn by cutting the molten resin. It is necessary to always form a new edge by contacting and abrading the surface.However, some resins have a low wear rate due to the cutting of the resin. In some cases, it is not necessary to push the knife. However, in the above-described conventional structure, a thrust for pressing the cutter knife against the die surface is always applied, and the pushing of the cutter knife cannot be stopped. Further, in the above-described conventional configuration, the die surface and the cutter knife are always in contact with each other with an appropriate pressing force and are rotating. For this purpose, the dies and cutter knives must be made of materials excellent in wear resistance, and for example, expensive materials such as TIC (titanium carbide alloy) are used. If the material of the cutter knife is made of inexpensive stainless steel or tool steel, the life of the cutter knife will be shortened.If the pressing force of the cutter knife is reduced for the purpose of extending the life of the cutter knife, discharge from the die The resulting resin pushed the cutter knife back, and a gap was formed between the die surface and the cutter knife, resulting in defective cutting. Further, the pressure of the cooling water in the cutter case may change suddenly (for example, when switching the three-way valve in the transport pipe line of the cut pellet).
However, the force in the retreating direction acts on the sleeve end surface exposed to the cutter case due to the instantaneously rising water pressure, the cutter knife is pushed back, and a gap is formed between the die surface and the cutter knife, resulting in poor cutting. Therefore, when such a sudden change in the water pressure is expected, it is necessary to previously set the pressure of the pressure medium supplied to the gap chamber for adjusting the forward thrust so that the forward thrust increases. When the forward thrust is increased, the cutter knife is pressed against the die surface with an unnecessarily large force, and the wear speed of the cutter knife is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in particular, a plastics material which achieves a long life of a cutter knife and stable granulation which is not affected by changes in cooling water pressure. It is an object of the present invention to provide a granulating apparatus.

[0011]

According to the present invention, there is provided an apparatus for granulating plastics, comprising: a cutter holder having a cutter knife rotatably driven along a die surface of a die; a cutter driving shaft for holding the cutter holder; A sleeve for internally holding the drive shaft so as to be rotatable and immovable in the axial direction; and a piston cylinder for holding and internally holding the sleeve, and using a part of the sleeve as a piston to move in the axial direction of the cutter drive shaft. In a plastics granulator comprising a housing capable of being provided, a brake device operated by a pressure medium is provided between the sleeve and the housing.

More specifically, the brake device comprises a brake drum provided on the sleeve and first and second brake drums arranged at outer peripheral positions of the brake drum and having different diameters.
A second holder, a diaphragm provided on an inner peripheral surface of the first holder, a brake shoe corresponding to the brake drum provided on an inner peripheral surface of the second holder, and a pressure medium supplied to the diaphragm. A third switching valve for switching between supply and discharge, and a third switching valve for adjusting the supply pressure of the pressure medium.
This is a configuration including a pressure regulating valve.

[0013]

In the plastics granulator according to the present invention, when a pressure medium is supplied to the diaphragm of the brake device, the diaphragm expands and the diaphragm pushes the brake shoe toward the brake drum. When a frictional force is generated between the sleeve and the housing to move relative to the housing in the axial direction, the frictional force can reduce the relative moving force or prevent the relative movement. The pressure medium changes the contact pressure between the brake shoe and the brake drum by adjusting the pressure, thereby adjusting the frictional force between the two members. Therefore, the relative movement of the sleeve with respect to the housing is prevented or the moving force is reduced. Is adjusted. When the pressure medium is discharged from the diaphragm, the diaphragm contracts and separates from the brake shoe. Therefore, the sleeve is free from the housing and freely moves in the axial direction.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a plastics granulator according to the present invention will be described below in detail with reference to the drawings.
The same or equivalent parts as those in the conventional example will be described with the same reference numerals. FIG. 1 is a configuration diagram having a partial cross section showing a plastics granulator according to the present invention, and FIG. 2 is a configuration diagram showing a main part of FIG. 1 in detail. In the figure, reference numeral 1 denotes a granulator, and the granulator 1 is attached in a state in which the molten resin extruded from an extruder (not shown) is closely attached to a manifold 2 which distributes the molten resin in a circumferential direction. The die 3 is fixed to the die surface 3a side via a cutter case 4.

The die 3 has a disk shape, and is provided with a large number of nozzles 6, 6,... Penetrating in the axial direction in a ring-shaped region surrounding the center. One end of the nozzle 6 opens into the ring-shaped resin passage 2 a of the manifold 2, and the other end opens into the cutter case 4.

One side of the cutter case 4 is detachably fixed to the surface 3a of the die 3 by bolts 7, and the granulator 1 is fixed to the other side by bolts 53. A cooling water inlet 8 is provided at a lower part and a cooling water outlet 9 is provided at an upper part, and the inside of the cutter case 4 is always filled with the cooling water.

In the granulator 1, a sleeve 52 is incorporated in the housing 15 via an O-ring 50 and a plurality of packings 51 so as to be movable by a predetermined distance in the axial direction. The cutter drive shaft 12 is coaxially rotatable via the shaft sealing device 54 and a pair of bearings 55 and is held immovable relative to the sleeve 52 in the axial direction (longitudinal direction). The cutter drive shaft 12 is provided with a bolt 1 at the tip protruding into the cutter case 4.
The cutter holder 10 rotates with the cutter drive shaft 12 via the key 10a and the key 10b and is detachably held.
A drive device (not shown) is connected to the rear end via a shaft joint (not shown) that can slide in the axial direction. A plurality of cutter knives 11, 11,... Are radially fixed and held on the end face of the cutter holder 10 facing the die 3, and each of the cutter knives 11 is attached to the die surface 3 of the die 3.
a, that is, the surface of the ring-shaped region where the nozzles 6, 6, ... are provided.

The sleeve 52 has a rear portion 52a as a piston, forms a piston cylinder together with a rear lid 63 between the sleeve 52 and the rear portion 15a of the housing 15, and is provided in a first gap chamber 56 formed on both sides of the rear portion 52a. Is the first hole 5
8, a second hole 59 is formed in communication with the second gap chamber 57. That is, the cutter driving shaft 12, the sleeve 52 and the housing 15 constitute an axial movement mechanism 100 of the cutter knife 11.

At the rear part 52a of the sleeve 52, a key 60 implanted in the radial direction is projected through a through groove 61 formed at the rear part 15a of the housing 15 to the outside. The detection rod 62a of the detection means 62 composed of a dial gauge or the like provided on the outer surface 15b of the housing 15 abuts. The sleeve 52
The rear part 52a holds the bearing 55 for rotatably supporting the cutter drive shaft 12 therein, and the rear end 52c includes
An adapter 67 for holding the bearing 55 to the sleeve 52 is fixed. At the rear of the adapter 67,
A cylindrical brake drum 67a is provided, and at the rear end of the rear lid 63, first and second holders 203, 203a, which are located apart from the outer peripheral portion of the brake drum 67a and have different diameters, are provided. It is fixedly arranged. The first holder 203 and the second holder 203a are coaxially spaced apart from each other, and a ring-shaped deformable diaphragm 202 is provided on the inner surface of the first holder 203. inner surface 202 is spaced at a small gap D ₁ is the outer surface of the second holder 203a. Wherein the inner surface of the second holder 203a, a brake shoe 201 which forms an annular is formed unitedly, a slight gap D ₂ between the outer peripheral surface of the inner peripheral surface of the brake shoe 201 and the brake drum 67a Is formed. Further, the second holder 203a and the brake shoe 201 are formed by dividing the circumference into several parts so as to be easily deformed. The diaphragm 202 is provided with a pressure medium supply / discharge hole 202a. The supply / discharge hole 202a is connected to a pressure medium source 69 that supplies a pressure medium such as compressed air or pressure oil via a third switching valve 211 and a third pressure regulating valve 210. The third pressure regulating valve 210 is provided with a pressure gauge 73 for monitoring the pressure of the pressure medium. That is, the brake drum 67a, the brake shoe 201, the diaphragm 202, the first holder 203, the second holder 203a, the third
The switching device 211 and the third pressure regulating valve 210 constitute the brake device 200.

Further, the pressure medium source 6 is inserted into the first hole 58 through a first switching valve 70 and a first pressure regulating valve 68.
9 and the second hole 59 is connected to the pressure medium source 6 via a second switching valve 72 and a second pressure regulating valve 71.
9 is connected. In order to monitor the pressure of the pressure medium supplied to the first hole 58 and the second hole 59, a pressure gauge 73 is connected to each of the pressure regulating valves 68 and 71. In this embodiment, the pressure medium supplied to the brake device 200 is obtained from the pressure medium source 69 for moving the sleeve 52 in the axial direction. However, this need not be common, and the pressure medium for the brake device 200 is not required. Separate sources may be used.

The apparatus for granulating plastics according to the present invention is configured as described above, and the method for granulating the plastics will be described below. First, when the second switching valve 72 is switched to the supply side and the first switching valve 70 is switched to the discharge side, the sleeve 5
2 moves to the die 3 side in the housing 15 by the same action as the piston by the pressure medium supplied to the second gap chamber 57, and the cutter knife 11 is pressed against the die surface 3a. In this state, the state at that time is set to zero by the detecting means 62.

When the cutter driving shaft 12 is rotated by a driving device (not shown) in the above-described state, the cutter knife 11 rotates at a high speed, and molten plastics (not shown) discharged from the nozzle 6 is moved by each cutter knife 11. The cut pellets are solidified by cooling water supplied from the cooling water inlet 8 into the cutter case 4 and sent together with the cooling water from the cooling water outlet 9 to a processing unit (not shown).
It is dried and commercialized.

When the above-mentioned cutter knife 11 rotates in water, a thrust (forward thrust) directed toward the dice 3 is generated.
In response to the forward thrust acting on the sleeve 52 via the cutter drive shaft 12 due to the rotation of the cutter knife 11, the first switching valve 70 is switched to the supply side, and the pressure medium is supplied to the first gap chamber 56 to resist the thrust. The force in the direction to retract
To counteract most of the forward thrust. That is, in order to cancel most of the forward thrust generated by the rotation of the cutter knife 11, the first pressure regulating valve 68 is
Each adjustment pressure is set to be higher than 1. By the above-described operation, the cutter knife 11 rotates in a state where the cutter knife 11 is constantly pressed against the die surface 3a by a desired, that is, optimal, weak pressing.

Next, in a state where the cutter knife 11 is rotating with an optimal pressing force against the die surface 3a, the third
The switching valve 211 is switched to the supply side to supply the pressure medium to the diaphragm 202. When the diaphragm 202 is elastically deformed and expanded by the pressure medium, the brake shoe 201 is pushed inward, the brake shoe 201 comes into contact with the outer peripheral surface of the brake drum 67a, and the sleeve 52 tries to move with respect to the housing 15. A frictional force is generated on the contact surface between the brake shoe 201 and the brake drum 67a, and acts to prevent this movement. The pressure of the pressure medium changes by changing the setting of the third pressure regulating valve 210. Therefore, the force for preventing the movement of the sleeve 52 can be changed by changing the frictional force of the contact surface. As before, the first pressure regulating valve 68 and the second
When the pressure control valve 71 is set, the brake device 2
When the cutter knife 11 is operated with the movement inhibition force set to a large value, the cutter knife 11 continues to rotate while being held at the position where it was first pressed, and thereafter, the cutter knife 11 moves forward to maintain the pressing force. There is no, it rotates at a certain position.

In this case, the pressing force of the cutter knife 11 gradually becomes weak due to the abrasion caused by sliding on the die surface 3a, and the abrasion caused by the sliding of the die surface 3a and the cutter knife 11 disappears. Also, the brake device 200 is
Prevents the cutter knife 11 from being pushed back or separated from the die surface 3a due to a sudden change in the resin discharge force from the die 3 or the cooling water pressure. Further, the movement inhibiting force of the brake device 200 is set small, and the pressing force acting on the sleeve 52 is set large.

In this case, the sleeve 52 moves forward with a reduced forward thrust. That is, while the sleeve 52 receives a large forward thrust, the cutter knife 11 always applies an optimal pressing force to the die surface 3a. Also in this case, the cutter knife 11 is prevented from being pushed back or separated from the die surface 3a by the frictional force of the brake device 200. The brake device 200 includes the third switching valve 21
When the pressure medium 1 is switched to the discharge side, the diaphragm 202 contracts as in the original state by forcibly discharging the pressure medium whose pressure has disappeared due to its own elasticity, and the brake shoe 20
1 is separated from the outer peripheral surface of the brake drum 67a. In this state, the first pressure adjusting valve 68 and the second
It moves forward or backward only in accordance with the set value of the pressure regulating valve 71.

[0027]

The plastics granulator according to the present invention is configured as described above, so that the following effects can be obtained. The cutter knife can be held with a small or almost zero pressing force against the die surface, and can be pushed back by resin pressure,
It does not recede due to the rapid fluctuation of the cooling water pressure and separate from the die surface. As a result, the wear rate of the cutter knife is reduced, the service life is extended, the frequency of replacement is reduced, the maintenance interval is extended, and long-term continuous granulation can be performed. In addition, the service life of the cutter knife can be greatly extended even when a stainless steel or tool steel material is used. Furthermore, since the contact state between the cutter knife and the die surface is always constant, the granulation conditions are constant, and the occurrence of defective products can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a plastics granulator according to the present invention.

FIG. 2 is a detailed configuration diagram of a main part of FIG. 1;

FIG. 3 is a cross-sectional configuration diagram showing a conventional device.

[Explanation of symbols]

 Reference Signs List 3 die 3a die surface 10 cutter holder 11 cutter knife 12 cutter drive shaft 15 housing 52 sleeve 56,57 gap chamber 67a brake drum 201 brake shoe 202 diaphragm 203 first holder 203a second holder

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B29B 9/00-11/16

Claims (2)

(57) [Claims] 1. A cutter holder (10) having a cutter knife (11) rotatably driven along a die surface (3a) of a die (3).
And a cutter drive shaft (12) for holding the cutter holder (10).
A sleeve (52) for holding the cutter drive shaft (12) rotatably and immovably in the axial direction, and a sleeve (5).
2) a housing (15) which holds the housing (15) and forms a piston cylinder using a part of the sleeve (52) as a piston, and is movable in the axial direction of the cutter drive shaft (12). A granulator for plastics, characterized in that a brake device (200) operated by a pressure medium is provided between the sleeve (52) and the housing (15). 2. The brake device (200) includes a brake drum (67a) provided on the sleeve (52), and first and second brake drums (67) provided at outer peripheral positions of the brake drum (67a) and having different diameters. 2 holders (203, 203a) and the first holder (20
3) a diaphragm (202) provided on the inner peripheral surface, and the brake drum provided on the inner peripheral surface of the second holder (203a).
(67a) and a corresponding brake shoe (201), a third switching valve (211) for switching between supply and discharge of the pressure medium supplied to the diaphragm (202), and a third switch valve for adjusting the supply pressure of the pressure medium. 2. The apparatus for granulating plastics according to claim 1, wherein said apparatus comprises a pressure regulating valve (210).