JP2579300B2 - Rotary cutter position adjustment device for pelletizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary cutter position adjusting device for adjusting a separation distance of a rotary cutter from a die plate in a pelletizer for manufacturing synthetic resin pellets.

[0002]

2. Description of the Related Art An outline of a conventional pelletizer will be described with reference to FIG. A large number of extrusion holes 22 are formed in a die plate 21 provided at the end of the extruder 2 in a line in a circle, and a rotary cutter 3 is provided facing the die plate 21. The molten resin extruded toward 23 is successively cut into pellets by the rotation of the rotary cutter 3 by the rotary shaft 4. Rotary cutter 3
An appropriate cooling fluid such as water or air is circulated inside the granulation chamber 23 in which the rotating pellets rotate, and the cut pellets are cooled and solidified by touching the cooling fluid, and then taken out to the outside. The rotary cutter 3 advances and retreats with respect to the opposing surface of the die plate 21 by the feed screw 43 to adjust the separation gap. Reference numerals 6 and 42 denote a worm and a worm wheel for giving this feed rotation, respectively. Reference numeral 41 denotes a pulley that drives the rotary shaft 4 to rotate.

[0003]

In a pelletizer, the clearance (clearance) between the rotary cutter 3 and the die plate 21 is extremely important. If the clearance is too small to come into contact with each other, In particular, abrasion of the rotary cutter 3 is caused and metal powder is mixed in the pellets. If the clearance is too wide, the resin is not sheared smoothly, and burrs commonly called "whiskers" are generated in the pellets. Invite the situation. Therefore, in the pelletizer, the clearance between the rotary cutter 3 and the die plate 21 is carefully set very delicately. However, it is affected by various factors that occur during operation, for example, the temperature rise of the extruder head. Since the above-mentioned clearance fluctuates due to the thermal expansion and elongation of the rotating shaft 4, the clearance value set prior to operation cannot be maintained at a constant value without fluctuating during operation. It is. Conventionally, readjustment of the clearance is performed by measuring the distance between the rotary cutter 3 and the die plate 21 using a clearance gauge or a dial gauge. However, this clearance measurement adjustment operation is extremely complicated, and this operation is also difficult. In this case, the operation of the pelletizer must be interrupted each time, so that the operation efficiency of the pellet production can be suppressed to a low level, and the improvement of the production efficiency cannot be expected.

[0004] Attempts to improve such inconveniences have not been completely eliminated. For example, 58
The cutter blade position adjusting device disclosed in JP-A-62613 is provided with a sensor that detects a change in the gap between the cutter blade and the die plate as a voltage change, facing the granulating chamber of the pelletizer, and is provided by the voltage detection sensor. The idea is to control the driving of the pilot motor in accordance with the change in the applied voltage, thereby automatically moving the cutter blade to and from the die plate. However, in this prior art, when cutting conductive resin, the voltage change is often uncertain, and the detected voltage value indicates the gap value between the cutter blade and the die plate. It is not possible to determine whether the resin shows the properties of the resin, and when cutting a resin that does not have conductivity, the resin will be present as an electrical insulating material in the gap between the cutter blade and the die plate. Therefore, it is difficult to achieve the intended purpose of always maintaining optimally the clearance between the cutter blade and the die plate.

[0005]

SUMMARY OF THE INVENTION The present invention provides an apparatus for adjusting the position of a rotary cutter in a pelletizer which can always quantitatively control the clearance between the rotary cutter of the pelletizer and the die plate to a desired optimum value without causing the above-mentioned problems. Specifically, the molten resin extruded toward the granulation chamber from the extrusion hole of the die plate provided at the end of the extruder, close to the extrusion-side end surface of the die plate In a pelletizer that cuts into a pellet shape by a rotating rotary cutter to produce the resin pellets, a contact detection circuit that forms an electrical closed circuit by the rotating cutter contacting the die plate,
An optical displacement meter that is provided inside the granulation chamber and measures the displacement amount of the rotary cutter, and is provided outside the granulation chamber and is AD-converted to the displacement amount measured by the optical displacement meter and is digitally converted. A rotary cutter position adjusting device in a pelletizer having a clearance indicator for displaying as a quantity.

The present invention also provides a rotary cutter position adjusting device for a pelletizer as described above, wherein a voltage output device for outputting a voltage corresponding to a difference between the display quantity of the clearance indicator and a predetermined reference amount, and the voltage output device A motor driven by the output voltage of the motor, a worm rotated by the motor, and a rotary cutter configured to move the rotary cutter in a direction approaching or away from the die plate by rotation of the worm. It is a position adjusting device.

[0007]

[Function] If the operator looks at the numerical value displayed on the clearance display and manually rotates the worm so that the numerical value becomes a desired optimum value, the position of the rotary cutter of the pelletizer can be easily adjusted to the optimum position. it can. Further, in the configuration in which the voltage output device is provided, the above-described manual adjustment operation can be fully automated, and monitoring of an operator is not required.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. FIG. 1 shows the second embodiment described later as it is, and in the case of the first embodiment, the figure to be referred to should be considered to be one in which elements indicated by reference numerals 91 and 92 in FIG. 1 are removed. . The molten resin of the pellets to be produced is extruded from the extrusion holes 22 of the die plate 21 of the extruder 2 by an extrusion screw drawn on the right side, and exits into a granulation chamber 23 cooled by an appropriate cooling medium. The end of the die plate 21 is cut by the rotating cutter 3 rotating close to the end face of the die plate 21 to continuously manufacture the pellets 1. The rotary cutter 3 is attached to an end of a rotary shaft 4 which is driven to rotate via a pulley 41. The rotary shaft 4 is rotated by a worm 6 via a worm wheel 42 so as to be integrally rotated therewith. The screw 43 is moved back and forth in its own longitudinal direction, whereby the rotary cutter 3 is moved.
Of the die plate 21 with respect to the facing surface, that is, the clearance in question here is adjusted.

An appropriate slip ring 71 is attached to the rotating shaft 4, and a lead is drawn out from the slip ring 71.
A lead wire connected to a part of 1 is taken out, and a loop-shaped contact detection circuit 7 including an appropriate low-voltage DC power supply 74 and an ammeter 73 is configured as shown in the figure. Then, the die plate 21 and the rotary cutter 3 rotate to form the pellet 1.
Is electrically insulated with a suitable electric insulating material 72 between the granulation chamber 23 and the wall of the granulation chamber 23. An optical displacement meter 5 for measuring the displacement of the rotary cutter 3 is provided in a part of the granulation chamber 23 so as to face the rotary cutter 3.
A clearance indicator 8 for converting the measurement data of the optical displacement meter 5 into an analog signal and digitally displaying the data is provided outside the granulation chamber 23 at a position that is easy for an operator to see.

The optical displacement meter 5 will be briefly described with reference to FIG. The drive circuit 51 excites an appropriate light emitting element 52 such as a light emitting diode or a semiconductor laser,
The light emitted from here is collected by the projection lens 53,
This is projected as a single beam onto a target object whose displacement is to be measured, for example, an object at the P position. Since the surface of the object is generally not a mirror surface, the projected light is diffusely reflected (irregularly reflected) at this point, and a part of the reflected light (the part having the highest energy) passes through the light receiving lens 54 onto the light position detecting element 55. The most conspicuous spot image P is formed. Here, focusing on the spot image P,
When the spot image P is displaced from the position to the Q position, the spot image P which is being watched now moves to the Q point on the light position detecting element 55. That is, the displacement of the object whose displacement is to be measured from the P position to the Q position is regarded as the movement of the spot image on the optical position detection element 55 from the point P to the point Q. Therefore, if the relationship between the displacement distance of the target object and the movement length of the spot image is known in advance, the displacement distance to be measured can be extracted and measured as a kind of analog quantity by the signal amplification circuit 56.

Returning to the description of the first embodiment of the present invention, first, several minutes after the start of the heating of the extruder 2, the thermal expansion of each part of the apparatus reaches a certain equilibrium state. Close to full, at this time contact detection circuit 7
Of the rotary cutter 3 contacts the die plate 21 by the operation of the ammeter 73. Assuming that this position of the rotary cutter 3 is a reference position, a displacement amount when the rotary cutter 3 is displaced in the axial direction of the rotary shaft 4 from the reference position by the optical displacement meter 5, that is, the rotary cutter 3 and the die plate. The clearance with the reference numeral 21 can be measured, and this clearance is AD-converted by the clearance display 8 and displayed as one digital quantity.

The preferred clearance between the rotary cutter 3 and the die plate 21 varies slightly depending on the resin used, but is preferably 30 to 50 μm. Therefore, the operator works while monitoring the clearance indicator 8, and when the clearance between the rotary cutter 3 and the die plate 21 deviates from the above-mentioned desired suitable value, the worm 6 may be adjusted by hand. .

A second embodiment of the present invention is shown directly in FIG. That is, in this embodiment, the operator does not operate the worm 6 by looking at the clearance between the rotary cutter 3 and the die plate 21 shown on the clearance display 8, but the display amount of the clearance display 8 is set to a predetermined optimum clearance. When a difference appears in comparison with the amount, a voltage output device 91 for generating an output voltage corresponding to the difference is provided, and the output voltage output from the voltage output device 91 is used to output the motor 9.
2, the worm 6 is automatically rotated by a predetermined amount in a predetermined direction by the motor 92, and the clearance between the rotary cutter 3 and the die plate 21 is adjusted.

[0014]

According to the apparatus of the present invention, the rotary cutter 3
The gap between the die and the die plate 21 is displayed as an easy-to-read digital value on the clearance display 8, and the operator looks at the value displayed on the clearance display 8, and
If the worm 6 is manually rotated so that the numerical value falls within a desired optimum value range, the position of the rotary cutter 3 of the pelletizer can be easily adjusted to the optimum clearance holding position. According to the configuration in which the voltage output device 91 and the motor 92 driven and controlled by the output voltage are provided,
The above manual adjustment work can be fully automated,
There is an advantage that monitoring of workers is almost unnecessary.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating the operating principle of an optical displacement meter used in the device of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pellet 2 extruder 21 die plate 22 extrusion hole 23 granulating chamber 3 rotating cutter 4 rotating shaft 5 optical displacement meter 6 worm 8 clearance display 91 voltage output device 92 motor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toraichi Ishikawa 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Hisao Sakaguchi 1-5-1, Kiba, Koto-ku, Tokyo Fujikura (56) References JP-A-4-28506 (JP, A) JP-A-58-62613 (JP, U) JP-A-59-146112 (JP, U) JP-A-62-38114 (JP, U) , U) Tokiko 56-46966 (JP, B2)

Claims (2)

(57) [Claims] 1. A molten resin extruded from an extrusion hole (22) of a die plate (21) provided at an end of an extruder (2) into a granulation chamber (23). The pelletizer cuts into pellets by a rotary cutter (3) rotating close to the extrusion-side end face of the resin to produce pellets of the resin.
And a contact detection circuit (7) that forms an electrically closed circuit by contacting the die plate (21), and is provided in the granulation chamber (23), and a displacement amount of the rotary cutter (3) is determined. An optical displacement meter (5) for measurement, and a clearance display provided outside the granulation chamber (23) and for converting the displacement measured by the optical displacement meter (5) from analog to digital and displaying it as a digital quantity. Rotary cutter position adjusting device in a pelletizer having a vessel (8). 2. A voltage output device (91) for outputting a voltage corresponding to a difference between a display quantity of the clearance display (8) and a predetermined reference amount, and driven by an output voltage of the voltage output device (91). The motor (92) to be controlled and this motor (9)
A worm (6) rotated by 2), and the rotation of the worm (6) causes the rotary cutter (3) to move in a direction toward or away from the die plate (21). A rotary cutter position adjusting device for a pelletizer according to claim 1.