JPH0550429A - Pelletizer - Google Patents

Abstract

PURPOSE:To cut easily a flexible strand such as an elastomer strand without so called long and oblique cutting due to miscut by providing a belt-like strand press pressing the strand on a strand supporting stage provided between a take-up roll and the apex of a fixed blade. CONSTITUTION:A belt-like strand press 9 pressing lightly from the upper side a strand to be cut is provided between a take-up roll 3 and the apex of a fixed blade 2. A soft and wear-resistant material such as a synthetic rubber is used as this strand press. It is thereby possible not only to pelletize polyolefin and polyamide but to cut easily a flexible strand without miscut or oblique cutting and to pelletize it with a uniform quality. The cost required for fixing this strand press 9 is extremely small. In addition, if the strand press 9 is fixed on a safety cover 10, it can be simply fixed and no special work is necessary and operation is safe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pelletizer (also called a strand cutter) for cutting organic polymer materials extruded in a strand form from an extruder into pellets.

[0002]

2. Description of the Related Art Most of thermoplastic resins are once pelletized and then molded into plastic molded articles. One of the methods for pelletizing is the strand cut method. In this method, the molten resin is extruded in the form of a string with a porous die attached to the tip of the extruder or the outlet of a gear pump, cooled, solidified, and then cut into short pieces with a pelletizer. Pelletizers generally sandwich and pull a plurality of string-shaped plastics, that is, strands, solidified by two take-up rolls, and deliver them at a predetermined speed onto a strand support surface between the take-up rolls and the fixed blade tip. ,
It has a structure that cuts with a rotary blade. The shape of the pellet is usually cylindrical.

By the way, if the pellets are not uniform in size and shape, not only the commercial value is impaired, but also clogging occurs in the molding process and the uniformity of the molded product is impaired, which is not preferable. Therefore, in order to manufacture uniform pellets, many technical proposals have been made for pelletizers. As a typical example, JP-A-49-5815
No. 2, JP 61-192494, and JP 2
-310009, Japanese Patent Laid-Open No. 3-61507,
Japanese Patent Publication No. 56-500169 and Japanese Utility Model Publication No. 62-87.
Inventions and devices described in the specification of No. 806 and the like can be mentioned. These inventions and devices have problems such as requiring a complicated control system, but relatively rigid polystyrene,
Some effects can be expected in cutting plastics such as polyethylene, polypropylene, and polyamide.

[0004]

However, from the past,
If you try to cut a relatively flexible strand of elastomer such as synthetic rubber with a pelletizer, you will get a miscut called long, or a diagonal cut,
At times, there was the problem of being almost impossible to cut. The solution of this problem cannot be expected even if the pelletizer improved by the above invention or device is used.

However, the invention described in Japanese Patent Laid-Open No. 3-61507 is aimed at cutting a flexible strand. This pelletizer uses a press roll and a belt conveyor inclined downward to introduce the strand into a take-up roll, guides it to a strand support with a fixed blade at the tip, and sprays the liquid from above while rotating it. It is cut with a blade. However, this pelletizer has a problem that the structure is complicated, the positional relationship with the front and rear devices is different from the conventional one, and a spray is required, so that the pelletizer cannot be easily introduced.

Therefore, the inventor of the present invention can easily cut not only a strand having normal hardness but also a soft strand such as rubber without causing long or slanted cuts. The structure is simple and easy to use. Researching pelletizers,
The present invention has been completed.

[0007]

SUMMARY OF THE INVENTION The present invention is a pelletizer for cutting a strand delivered from a take-up roll at a predetermined speed between a rotary blade and a fixed blade, and between the take-up roll and the fixed blade tip. Provided is a pelletizer characterized in that a strip-shaped strand retainer for retaining the above-mentioned strand is provided on the provided strand support base surface.

Further, among the above-mentioned pelletizers, one having a simple structure and easy to use is that the above-mentioned strand retainer is attached to the tip of the safety cover of the rotary blade or take-up roll which is rotatably provided by a hinge. The present invention provides a pelletizer that is characterized by

[0009]

FUNCTION AND EXAMPLE OF EMBODIMENT The present invention will be described below with reference to the drawings showing an example of embodiment. FIG. 1 is a schematic side sectional structural view showing an embodiment of a pelletizer of the present invention.

Although not shown, the strand to be cut is usually a plurality of strands.
It is taken up by a take-up roll 3 consisting of a lower roll 5 and the lower roll 5, and is sent to the fixed blade 2 at the tip thereof on the strand support base surface 8 while being prevented from being wound around the lower roll 5 by the scraper 6. The rotary blade 1 having a gear-shaped blade and the fixed blade 2 cut the sent strand into a predetermined length. The cutting length of the strand is determined by adjusting the rotation speed of the rotary blade 1 and the feed speed of the strand.

The inventor of the present invention has studied the cause of long or oblique cuts or inability to cut in the flexible strand cutting. As a result, when the strand is soft, the strand is pulled by the take-up roll 3 due to the shearing force at the time of cutting. And cutting position 15
It was found that it was not possible to cut accurately because it freely moved between and, the cutting surface was not fixed, and it was caught between the blades of the rotary blade.

Then, as a result of trial and error of means for stabilizing the running of the strand during cutting, surprisingly, a strip-shaped strand retainer 9 is provided between the take-up roll 3 and the tip of the fixed blade 2 for cutting. It has been found that the above problems can be completely solved by a very simple means of lightly pressing the strand from above onto the strand support base surface 8.
Unlike the invention described in Japanese Patent Application Laid-Open No. 3-61507, there is no need to hold the press roll, spray, or diagonally attach the strand base.

The position for pressing the strand is the take-up roll 3
The distance between the fixed blade 2 and the tip of the fixed blade 2, the traveling speed of the strand, the type of the strand, etc. may be slightly different, but the closer to the tip of the fixed blade 2, the more effective it is.
Particularly effective is within m. The strand retainer 9 can retain a plurality of strands by being provided in a strip shape in a direction substantially perpendicular to the traveling direction of the strands so as to fill the traveling width. It is sufficient to press the strand very lightly. If the size is too large, the smooth running of the strand will be hindered, so care must be taken. Therefore, it is not preferable to use metals for the material of the strand presser 9, and it is appropriate to use synthetic or natural rubber, a composite material of these rubbers and fibers, or a flexible and wear-resistant material such as a brush. Is.

When the strand retainer 9 is attached, it is desirable that the strand retainer 9 can be moved upward or toward the machine side so that the strand can be easily passed through before the operation of the pelletizer. The preferred concrete means is to attach the strand presser 9 to the safety cover 10 of the rotary blade 1. The safety cover 10
In general, a hinge 11 is attached to the base on the side opposite to the strand insertion side so as not to interfere with the running of the strand, and the tip end on the strand insertion side can be rotated and opened upward. FIG. 2 is a front view of the safety cover 10 to which the strand retainer 9 given as an example of the embodiment is attached (A-A 'in FIG. 1).
Direction). The tip portion of the safety cover 10 is notched in order to secure the traveling path of the strand. If the strand retainer 9 is fixed to the notch with the fixing member 12, the strand retainer 9 can be attached without the need for any other special attachment member, and no special work is required during operation. If the opening / closing operation of the safety cover 10 and the operation switch of the device are locked, it is possible to easily and safely guide the strand before the operation.
13 is a bed, and 14 is a fixed blade base.

Further, depending on the structure of the pelletizer, the safety cover of the take-up roll may be attached to the base by a hinge, and its tip may be closer to the cutting position than the tip of the safety cover of the rotary blade. is there. In such a pelletizer, it is better to attach the strand presser to the tip portion of the safety cover of the take-up roll.

[0016]

EXAMPLE A strand presser similar to that shown in the drawing was attached to a safety cover of a fixed blade of a pelletizer (TMS type manufactured by Tanaka Iron Works Co., Ltd.) having substantially the same structure as shown in FIG. I confirmed the effect. The width of the notch through which the strand at the tip of this safety cover was passed was about 150 mm. About 1.5 mm thick and 30 m wide in this notch
m, wear-resistant silicon rubber having a length of about 150 mm, using a strip-shaped metal mounting member having a width of about 20 mm and a length of about 150 mm, the distance between the tip of the silicon rubber and the strand support is about 3 mm. Installed. Furthermore, the tip of the silicone rubber was adjusted so that the strand came into contact with the strand and was pressed very lightly to obtain a strand presser. The horizontal distance between the tip of the silicone rubber and the cutting position was about 2 mm.

Twenty-one flexible synthetic rubber strands having a diameter of about 3 mm were aligned on this pelletizer, drawn by a take-up roll at a speed of about 50 m / min, introduced onto a strand support stand, and cut into a length of 3 mm. The strand was able to be cut uniformly and stably without the occurrence of long cuts and oblique cuts due to miscuts.

Next, for comparison, the strand holder was removed and the same strand was tried to be cut, but it was impossible to cut at all.

[0019]

When the pelletizer of the present invention equipped with a very simple strand retainer is used, not only pelletization of polyolefin and polyamide but also flexible strands such as elastomer, which have hitherto been impossible, can be cut into long or slanted lines by miscutting. It is possible to easily cut and supply pellets of uniform quality without causing cutting. The cost for mounting the strand retainer is extremely low.

Further, if the strand presser is attached to the safety cover, it can be attached very easily without requiring any special attaching member, and no special work is required during operation, and the operation is safe.

[Brief description of drawings]

FIG. 1 is a schematic side sectional structural view showing an example of an embodiment of a pelletizer of the present invention.

[Fig. 2] Safety cover 8 with a strand presser 9 attached
Front view (direction AA ′ in FIG. 1).

[Explanation of symbols]

1: Rotating blade 2: Fixed blade 3: Take-up roll 4: Upper roll 5: Lower roll 6: Scraper 7: Chute 8: Strand support surface 9: Strand retainer
10: Safety cover 11: Hinge 12: Fixing member 13: Bed 14: Fixed blade stand 15: Cutting position

Claims (2)

[Claims] 1. In a pelletizer for cutting a strand delivered from a take-up roll at a predetermined speed between a rotary blade and a fixed blade, on a strand support base surface provided between the take-up roll and the tip of the fixed blade. A pelletizer characterized in that a band-shaped strand retainer for retaining the above-mentioned strand is provided on the. 2. The pelletizer according to claim 1, wherein the strand retainer is attached to a tip end portion of a safety cover of a rotary blade or a take-up roll which is rotatably provided by a hinge.