JPH0596533A - Adjusting device for position of rotary cutter in pelletizer - Google Patents

Abstract

PURPOSE:To provide the title device capable of always easily and quantitatively controlling the clearance between a rotary cutter and a die plate to the optimum range. CONSTITUTION:An optical displacement meter 5 is provided in the pelletizing chamber 23 of a pelletizer in opposed relation to a rotary cutter 3 and the spaced-apart distance of the rotary cutter 3 from the contact position of the rotary cutter 3 with a die plate 21 capable of being accurately known by a contact detection circuit 7, that is, the clearance between the rotary cutter 3 and the die plate 21 is displayed on a clearance display device 8 as digital quantity. Further, a voltage output device 91 outputting the voltage corresponding to the difference between the displayed numerical value of the clearance display device 8 and a predetermined optimum clearance is provided and the driving of a motor 92 is controlled on the basis of the output voltage and a worm 6 is rotated to automatically allow the rotary cutter 3 to advance and recede with respect to the die plate 21 to adjust the clearance.

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 the 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 circle in a die plate 21 provided at the end of the extruder 2. A rotary cutter 3 is provided so as to face the die plate 21, and a granulation chamber is formed from the extrusion holes 22. The molten resin extruded toward 23 is cut into pellets one after another by the rotational drive of the rotary cutter 3 by the rotary shaft 4. Rotating cutter 3
An appropriate cooling fluid such as water or air is circulated inside the granulating chamber 23 in which is rotated, and the cut pellets are brought into contact with the cooling fluid to be cooled and solidified, and then taken out to the outside. The rotary cutter 3 is moved forward and backward by the feed screw 43 with respect to the facing surface of the die plate 21 to adjust the clearance, and reference numerals 6 and 42 denote a worm and a worm wheel for giving the feed rotation, respectively. Further, reference numeral 41 denotes a pulley that rotationally drives the rotary shaft 4.

[0003]

In the pelletizer, the clearance between the rotary cutter 3 and the die plate 21 is extremely important. If the clearance is so narrow that they come in contact with each other, In particular, abrasion of the rotary cutter 3 is caused and metal powder is mixed into the pellets. If the clearance is too wide, the resin is not sheared smoothly, and burrs commonly called "whiskers" occur on the pellets. Cause a situation. Therefore, in the pelletizer, the clearance between the rotary cutter 3 and the die plate 21 is set very delicately and carefully, but it is affected by various factors that occur during operation, for example, the temperature rise heat of the extruder head. Since the clearance fluctuates due to the thermal expansion of the rotating shaft 4 and the like, the value of the clearance set prior to the operation cannot be maintained at a constant value without fluctuating during operation. Is. Conventionally, the clearance is readjusted by measuring the distance between the rotary cutter 3 and the die plate 21 with a gap gauge or a dial gauge, but this clearance measurement adjustment work is extremely complicated, and this work is also difficult. In order to do so, the operation of the pelletizer must be interrupted each time, so the operating efficiency of pellet production was suppressed to a low level, and improvement in production efficiency could not be expected.

There has been no attempt to improve such inconvenience. For example, the actual exploitation 58
The cutter blade position adjusting device disclosed in Japanese Patent Laid-Open No. 62613 is provided with a sensor that faces the granulating chamber of the pelletizer and that detects a gap change between the cutter blade and the die plate as a voltage change. The idea is to control the drive of the pilot motor according to the change of the applied voltage, thereby automatically moving the cutter blade back and forth with respect to the die plate. However, in this prior art, when cutting a resin having conductivity, the voltage change often becomes uncertain, and whether the detected voltage value indicates the gap value between the cutter blade and the die plate, It is impossible to determine whether it shows the characteristics 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. Since it becomes impossible to measure such a large voltage change, it is difficult in reality to achieve the intended purpose of always maintaining the optimum clearance between the cutter blade and the die plate.

[0005]

According to the present invention, there is provided a position adjusting device for a rotary cutter in a pelletizer, which can always quantitatively control a clearance between a rotary cutter of a pelletizer and a die plate to a desired optimum value without causing the above-mentioned problems. Specifically, the molten resin extruded from the extrusion hole of the die plate provided at the end of the extruder toward the granulation chamber, in the vicinity of the extrusion side end surface of the die plate. In a pelletizer that produces pellets of the resin by cutting into pellets by a rotating cutter that rotates, a contact detection circuit that constitutes an electrically 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 a displacement amount that is provided outside the granulation chamber and that is measured by the optical displacement meter are digitally converted by AD conversion. It is a rotary cutter position adjusting device in a pelletizer having a clearance indicator for displaying as a quantity.

Further, according to the present invention, in the rotary cutter position adjusting device for the above-mentioned pelletizer, a voltage output device for outputting a voltage according to a difference between the display quantity of the clearance display and a predetermined reference quantity, and this voltage output equipment. A drive controlled by an output voltage of the motor, a worm rotated by the motor, and a rotary cutter configured such that the rotation of the worm causes the rotary cutter to move in a direction toward or away from the die plate. It is a position adjusting device.

[0007]

[Operation] If the operator looks at the numerical value displayed on the clearance indicator and manually rotates the worm so that the numerical value becomes the 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-mentioned manual adjustment work can be fully automated, and the operator's monitoring is unnecessary.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. This FIG. 1 shows a second embodiment which will be described later as it is, and in the case of the first embodiment, it should be considered that the drawing to be referred to has the elements denoted by reference numerals 91 and 92 in FIG. 1 removed. . The molten resin of pellets to be produced is extruded from the extrusion hole 22 of the die plate 21 of the extruder 2 by the extrusion screw drawn on the right side, and is discharged into the granulation chamber 23 cooled by an appropriate cooling medium. Pellets 1 are continuously manufactured by cutting the place where it comes close to the end surface of the die plate 21 by the rotating cutter 3 which is rotating. The rotary cutter 3 is attached to an end portion of a rotary shaft 4 which is rotationally driven via a pulley 41, and the rotary shaft 4 is fed by a worm 6 via a worm wheel 42 so as to rotate integrally therewith. The screw 43 causes the rotary cutter 3 to move forward and backward in the longitudinal direction thereof.
The distance to the facing surface of the die plate 21, that is, the clearance at issue here is adjusted.

An appropriate slip ring 71 is attached to the rotary shaft 4 and a conductive wire is drawn from this, while the die plate 2
A conducting 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 illustrated. Then, the die plate 21 and the rotary cutter 3 rotate to rotate the pellet 1
An appropriate electric insulating material 72 is used to electrically insulate between the wall surface that defines the granulation chamber 23 for forming the granules. An optical displacement gauge 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 AD-converting the measurement data of the optical displacement meter 5 and digitally displaying the data is provided outside the granulation chamber 23 at a position where the operator can easily see.

The optical displacement gauge 5 will be briefly described with reference to FIG. The drive circuit 51 excites a suitable 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 beam is projected as a beam onto a target object whose displacement is to be measured, for example, an object at the P position. Since the surface of this object is not generally a mirror surface, the projection light is diffusely reflected (diffusely reflected) here, and a part of the reflected light (the portion with the highest energy) passes through the light receiving lens 54 and is incident on the optical position detection element 55. The most conspicuous spot image P will be connected. Here, while paying attention to this spot image P, the target object P
If the position image is displaced from the position to the Q position, the spot image P, which is currently being noticed, moves to the Q point on the optical 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 can be grasped as the movement of the spot image on the optical position detection element 55 from the P point to the Q point. Therefore, if the relationship between the displacement distance of the 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 the description to the first embodiment of the present invention, first, after the heating of the extruder 2 is started for several minutes, the thermal expansion of each part of the apparatus reaches a balanced state to some extent, and then the rotary cutter 3 is attached to the die plate 21. Bring it close to full, and at this time contact detection circuit 7
It is known that the rotary cutter 3 has come into contact with the die plate 21 by the operation of the ammeter 73. If this position of the rotary cutter 3 is set as the reference position, the displacement amount when the rotary cutter 3 is displaced in the axial direction of the rotary shaft 4 from the reference position by the above-described optical displacement gauge 5, that is, the rotary cutter 3 and the die plate. The clearance with 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 is 30 to 50 μm, although it varies slightly depending on the resin used. 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 desired desired value described above, the worm 6 may be manually turned to adjust. .

A second embodiment of the 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 indicator 8, but the displayed amount on the clearance indicator 8 is a predetermined optimum clearance. A voltage output device 91 is provided which generates an output voltage corresponding to the difference when compared with the amount, and the motor 9 is driven by the output voltage output from the voltage output device 91.
2 is drive-controlled, and the motor 92 automatically rotates the worm 6 in a predetermined direction by a predetermined amount to adjust the clearance between the rotary cutter 3 and the die plate 21.

[0014]

According to the apparatus of the present invention, the rotary cutter 3
The clearance between the die plate 21 and the die plate 21 is displayed on the clearance display 8 as an easy-to-see digital numerical value.
By manually rotating the worm 6 so that the numerical value falls within a desired optimum range, the position of the rotary cutter 3 of the pelletizer can be easily adjusted to the optimum clearance holding position. Further, according to the configuration in which the voltage output device 91 and the motor 92 whose drive is controlled by the output voltage thereof 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 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]

 1 Pellet 2 Extruder 21 Die plate 22 Extrusion hole 23 Granulation chamber 3 Rotating cutter 4 Rotating shaft 5 Optical displacement meter 6 Worm 8 Clearance indicator 91 Voltage output device 92 Motor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toraichi Ishikawa 1-5-1, Kiba, Koto-ku, Tokyo Within Fujikura Electric Wire Co., Ltd. (72) Inventor Hisao Sakaguchi 1-1-5, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd.

Claims (2)

[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), said die plate (21). In a pelletizer for producing pellets of the resin by cutting into pellets by a rotary cutter (3) that rotates in proximity to the end face on the extrusion side of the rotary cutter (3).
Is provided in the granulation chamber (23) and the contact detection circuit (7) that forms an electrical closed circuit by contacting the die plate (21) with the displacement amount of the rotary cutter (3). An optical displacement meter (5) for measurement and a clearance display provided outside the granulation chamber (23) and AD-converting the displacement amount measured by the optical displacement meter (5) and displaying it as a digital amount. Rotary cutter position adjusting device in a pelletizer having a container (8). 2. A voltage output device (91) for outputting a voltage according to a difference between the display quantity of the clearance display device (8) and a predetermined reference quantity, and driven by an output voltage of the voltage output device (91). The controlled motor (92) and this motor (9
The worm (6) rotated by 2) and the rotation of the worm (6) move the rotary cutter (3) toward or away from the die plate (21). The rotary cutter position adjusting device in the pelletizer according to claim 1.