JP2000176932A - Cutter edge of plastic granulating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep cutting performance for a long period and to granulate continuously for a long period by forming a high hardness coating layer at the tip edge of a surface contacting the die surface of a blade edge. SOLUTION: In a tip edge part 15a to be a terminal edge part cutting a resin of a contact surface 15 contacting a die surface with which one surface of the blade edge 12 of a cutter blade 11 is contacted and a part other than a base end edge part 15b on the opposite side to it, a base material is exposed to the surface. All the surface of the base material 13 other than the exposed part of the contact surface 15 is coated with a high hardness coating layer 14. Cutter steel is used for the base material 13, and hard ceramic such as TiN, TiC, and SiC is used for the layer 11. The layer 14 is made by a method in which the whole blade is coated with the layer 14 in advance, and a part of the contact surface is cut off. In this way, good cutting performance is kept for a long period, the breakage of the blade edge 12 and burrs are prevented, the abrasion of the blade edge 12 itself and the die surface is minimized, a long life is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutter blade attached to a plastic granulator for cutting a molten resin, the cutting blade having a long cutting ability.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a plastic granulating apparatus. In the figure, reference numeral 1 denotes an extruder main body, and 2 denotes a die attached to the tip of the extruder main body 1. The die 2 has a large number of resin discharge holes (not shown). Also,
A cutter device 3 is provided on the front surface of the die 2 so as to be able to advance and retreat with respect to the die 2.

[0003] The cutter device 3 includes a pedestal 4 capable of moving forward and backward with respect to the die 2, a rotary drive source 5 such as a motor fixed to the pedestal 4, and a rotary shaft 6 of the rotary drive source 5.
And a plurality of cutter blades 8 attached to the base plate 7 attached to the base plate 7.
8 ... These cutter blades 8, 8 ...
As shown in FIG. 3, it is mounted on the base plate 7 in the form of a propeller and its blade surface faces the die 2. By rotating the rotary drive source 5, the cutter blades 8 are rotated, and by moving the pedestal 4, the cutter blades 8 are moved closer to or away from the die 2.

FIG. 4 shows the cutter blade 8 described above.
The cutter blade 8 is a single-sided blade having a rectangular parallelepiped appearance, and mounting holes 9 and 9 are drilled at its base. The cutter blade 8 is made of blade steel such as SUS440C, and its cutting edge is quenched and sharpened.

In order to perform plastic granulation using such a plastic granulator, first, the cutter device 3 is brought close to the die 2, and the cutting edges of the cutter blades 8 are gently pressed against the surface of the die 2. Then, it is fixed at a position where it rotates while sliding on the surface of the die 2. Next, the extruder main body 1 is operated, the molten resin is extruded into a rod shape from the resin discharge hole of the die 2, and the cutter blades 8, 8 are rotated. Thereby, when the molten resin extruded from the resin discharge hole of the die 2 has a length of 2 to 5 mm, the molten resin is cut by the rotating cutter blades 8, 8,. The target pellets are manufactured by flowing cooling water or cooling air into the jacket 10 and air-cooling or water-cooling it.

[0006] In such a cutter device 3, when the cutter blades 8, 8... Cut the resin, the cutting edge gradually wears and the sharpness falls, but at the same time, the cutting edge is changed to the surface of the die 2. The surface of the die 2 is polished as a kind of honed stone because the die 2 rotates while being pressed against.
At this time, if the cutting edges of the cutter blades 8, 8,... Are too hard, the tips of the cutting edges may be chipped during rotation. If the cutting edges are too soft, the tips of the cutting edges may bend and burrs may appear, and in all cases, the sharpness of the cutting edges And it was difficult to maintain good sharpness for a long time.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to make it possible to maintain the sharpness of a cutter blade attached to a cutter device of a plastic granulator for a long period of time, and to achieve long-term continuous granulation. Is to be able to do it.

[0008]

This problem can be solved by providing a high-hardness coating layer on the edge of the surface of the blade of the cutter blade in contact with the die surface. The Vickers hardness of the base material of the cutting edge is 500 to 700, the Vickers hardness of the high hardness coating layer is 800 to 1800, and the hardness difference between the high hardness coating layer and the die surface is 200 to 1000 in Vickers hardness. It is desirable that

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
FIG. 1 shows an example of the cutter blade of the present invention. The cutter blade 11 has a contact surface 15 in which one surface of a blade edge 12 is in contact with a die surface. The base material 13 is exposed on the surface of the contact surface 15 except for the front edge 15a serving as the edge for cutting the resin and the base edge 15b on the opposite side. The entire surface of the base material 13 including the distal edge 15a and the proximal edge 15b other than the exposed portion is coated with the high hardness coating layer. The base material 13 has a Vickers hardness of 500.
To 700, preferably 530 to 620, and more preferably 540 to 600. High hardness coating layer 14
Has a Vickers hardness of 800 to 1800,
Preferably 1000 to 1400, more preferably 12
00 to 1400. The difference between the hardness of the high hardness coating layer 14 and the surface of the die 2 is Vickers hardness of 200.
To 1000, preferably 400 to 800, and more preferably 500 to 700.

The steel material forming the base material 13 is SUS
Knife steel such as 440C is used. For the high hardness coating layer 14, a hard ceramic such as TiN, TiC, or SiC is used, and TiN is particularly preferable.
The thickness is 1 to 10 μm, preferably 2 to 7 μm,
More preferably, it is 3-5 μm. 1 μm thick
If it is less than 10 μm, the sharpness is insufficient, and if it exceeds 10 μm, chipping of the high-hardness coating layer 14 causes cutting failure. The high-hardness coating layer 14 is formed by a normal CVD method or the like. The high-hardness coating layer 14 is formed by previously coating the entire blade with the high-hardness coating layer 14 and then shaving off the contact surface 15.

If the Vickers hardness of the base material 13 is less than 500, it is too soft, and the cutting edge may be deformed while the cutter blade 11 is operating. On the other hand, if it exceeds 700, it becomes too hard, becomes brittle, and wears the surface of the die 2 greatly. Hardness of high hardness coating layer 14 is 8
If it is less than 00, the sharpness is poor, and if it exceeds 1800, it tends to chip. The difference between the Vickers hardness of the high hardness coating layer 14 and the Vickers hardness of the surface of the die 2 is 20.
When it is less than 0, the wear of the high hardness coating layer 14 increases, and the sharpness is reduced at an early stage. The difference is 10
If it exceeds 00, wear on the surface of the die 2 becomes large.

In such a cutter blade 11, the contact surface 15 of the blade edge 13 slides while contacting the surface of the die 2,
The exposed base material 13 occupying most of the contact surface 15 and the front edge 15a and the base edge 15b rotate while sliding on the surface of the die 2 to cut the resin at the front edge 15a. Since the surface hardness of the tip edge 15a of the cutting edge 12 is sufficiently high, the sharpness to the resin is good. Also,
Since the cutting edge is hard, burrs are not easily formed on the cutting edge 12 when the cutter blade 11 slides on the surface of the die 2. Further, since the base material 13 is softer than the high hardness coating layer 14, the cutting edge 1
2 is not chipped, and even if it is chipped, only the thin high-hardness coating layer 14 is chipped, and the chip is small. Furthermore, since most of the contact surface 15 is the soft base material 13, the surface of the die 2 is not unnecessarily worn during operation, and the life of the die 2 is extended. In addition, since the difference in hardness between the high-hardness coating layer 14 and the surface of the die 2 is appropriate, the high-hardness coating layer 14 and the base material 13 are excessively worn, or the surface of the die 2 is excessively worn. And both have a longer life. As a result, a long-term continuous operation of the granulating apparatus becomes possible, maintenance is reduced, labor and cost are reduced. In the present invention, the present invention is not limited to the above embodiment, and the function can be sufficiently achieved if the high-hardness coating layer 14 is present only at the leading edge 15a for cutting the resin.

A specific example will be described below. Vickers hardness 56
FIG. 1 is attached to the edge of a cutter blade made of SUS440C of No. 0.
As shown in FIG.
a and a 2 μm thick Ti including the base edge portion 15 b
A high hardness coating layer made of N was coated by a CVD method to form a cutter blade. The plain Vickers hardness of this TiN was 1300. On the other hand, the die is SUS53
0 and a Vickers hardness of 700 whose surface was nitrided was used.

The above-mentioned cutter blade was pressed against the die surface, rotated while sliding, and a pellet of polypropylene was produced. After a total operating time of 400 hours, the state of the cutting edge of the cutter blade was observed with a magnifying glass, and no large chipping or burrs were observed. In addition, good sharpness continued until 700 hours later. On the other hand, when the wear amount of the die surface was determined, the wear depth was 2000 μm, which was extremely small.

On the other hand, polypropylene pellets were manufactured using a cutter blade (Vickers hardness 550) made of conventional SUS440C blade steel and having a hardened blade edge, and the operation time was 24 hours. As a result, burrs were generated, the sharpness was reduced, and replacement of the cutter blade was required.

[0016]

As described above, claims 1 and 2
In the cutter blade described in (1), good sharpness is maintained over a long period of time, there is no chipping and burrs of the cutting edge, the wear of the cutting edge itself and the die surface is slight, the life is long, and the operating cost can be reduced. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a cutter blade of the present invention in a partial cross-sectional view.

FIG. 2 is a schematic configuration diagram showing a plastic granulator.

FIG. 3 is a perspective view showing a main part of a plastic granulator.

FIG. 4 is a perspective view showing a conventional cutter blade.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Cutter blade 12 Cutting edge 13 Base material 14 Hard coating layer 15 Contact surface 15a Tip edge

Claims (2)

[Claims] 1. A cutter blade for cutting a resin extruded from a resin discharge hole of a die by sliding while a cutting edge of the cutting edge is pressed against a surface of a die of an extruder, wherein a contact surface of the cutting edge contacts a die surface. A cutter blade of a plastic granulator, wherein a high hardness coating layer is provided on a tip edge portion. 2. The Vickers hardness of the base material of the cutting edge is 500 to 500.
700, Vickers hardness of high hardness coating layer is 80
The cutter blade according to claim 1, wherein the difference between the hardness of the high hardness coating layer and the surface of the die is 200 to 1000 in Vickers hardness.