JPH08207116A - Method and apparatus for adjusting clearance of twin extrusion screw - Google Patents

Abstract

PURPOSE: To eliminate the damage of a screw or the inner wall of a cylinder during extrusion molding, to stabilize a molding condition and to produce a molded product of excellent quality with good productivity. CONSTITUTION: The positional shift of screw bearing parts 8a, 8b is measured by displacement sensors 9a, 9b to be transmitted to an operation part 13 and the clearance between screw flights is operated from the measured values by the operation part 13 to calculate the deviation with an inputted set value and the position of a gear rotary shaft 6a is finely moved by the force of the oil compressor 17 connected to the rear end of the gear rotary shaft 6a so as to eliminate the deviation and the position of the screw bearing part 8a is corrected in cooperation with this fine movement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for adjusting clearance between screw flights of a twin-screw extruder used when a plastic material such as synthetic resin or rubber is extrusion-molded.

[0002]

2. Description of the Related Art Conventionally, as a twin-screw extruder, a cantilever type two screws are arranged in parallel in a cylinder, and the respective flights are engaged with each other to rotate in mutually different directions. Has been done.

With respect to the screws of such a twin-screw extruder, a force that presses each screw toward the inner wall of the cylinder at the time of extrusion molding acts, the shaft center of the screw becomes eccentric, and the clearance between flights becomes abnormal. There is a problem that friction with the inner wall of the cylinder at the top of the flight and pressure rise of the molten resin at the meshing part of the flights easily occur, resulting in damage to the screw flight and the inner wall of the cylinder, or deterioration of product quality due to overheating of the molten resin. Various attempts have been made to suppress the pressure rise of the molten resin.

Japanese Patent Laid-Open No. 63-29, which was previously developed by the present applicant.
The technique described in Japanese Patent No. 7022 is one of them. This technique is a technique in which the side wall of the flight is formed into a curved surface having a special shape, that is, by devising the shape of the flight, an abnormal rise in pressure and temperature of the molten resin is suppressed. As a result, the eccentricity of the twin screw was reduced, damage to the inner wall surface of the cylinder and flight was reduced, and the frequency of member replacement could be reduced. Further, the material resin can be uniformly melted and kneaded under an appropriate temperature and pressure, and the quality of the product can be improved to a considerable extent.

[0005]

However, recently, there is an increasing tendency for users to demand products of higher quality, and it is necessary to further improve quality. In addition, since the problem caused by the eccentricity of the twin screw has been taken for the first time by inspecting the product and taking action, the occurrence rate of defective products is large and cost reduction can be achieved. could not.

In view of the above market situation, the present invention eliminates the drawbacks of the prior art, eliminates the damage to the equipment in the extrusion molding process, and stabilizes the molding conditions, thereby improving the productivity. The object of the present invention is to provide a method and an apparatus for adjusting the clearance of a twin-screw extrusion screw that can be manufactured continuously well.

[0007]

According to a second aspect of the invention described in claim 1,
The method for adjusting the clearance of the axial extrusion screw is as follows: "Measure the positional deviation of the screw bearing portion of a twin-screw extruder having screws arranged in the cylinder and rotating in mutually different directions, and measure the measured value between the screw flights. The clearance is calculated, the obtained clearance is compared with the initial set value to find the deviation, and the clearance is controlled by correcting the position of the screw bearing portion so as to eliminate this deviation. " According to this, one of the above objects can be achieved.

According to a second aspect of the present invention, there is provided a clearance adjusting device for a twin-screw extruding screw, comprising: a detecting section having a displacement sensor for detecting a positional deviation of the screw bearing section, and a clearance setting between the flight and a detecting section. Is attached to the gear rotation shaft of the drive unit that cooperates with the screw bearing unit, and the calculation unit that calculates the clearance between screw flights based on the signal from, calculates the deviation between the clearance and the set value, and transmits the control command. An oil compression device that can finely move the position of the gear rotation shaft, a displacement sensor that detects the position of the gear rotation shaft, a pressure and a flow rate of the hydraulic oil supplied to the oil compression device in response to a command from the displacement sensor and the calculation unit. And a control section having an actuating hydraulic valve for adjusting. " One is achieved.

In the extrusion molding by the twin-screw extruder, the inventors of the present invention pursued a means for reducing the eccentricity of the screw shaft center in the extrusion molding process and maintaining a normal flight clearance. Experiments of extrusion molding with various combinations of molding elements such as molding material, molding conditions, etc. were accumulated, and the data on the correlation between the condition of each part of the molding device during molding and the quality of the product were summarized.

As a result, when the screw shaft is eccentric and the clearance between the screw flights becomes abnormal, a positional deviation of the screw bearing portion is recognized, and in some cases, in addition to this positional deviation, the tip end portion in the cylinder is It has been found that the pressure of the molten resin is also relevant. Also, the screw bearing part is connected to the gear rotation shaft in the drive part of the extruder and works in cooperation with each other.Therefore, if these phenomena are combined and developed, the clearance between screw flights during machine operation will be reduced. When an abnormality occurs, the inventors have found that there is a possibility that this can be automatically corrected, and completed the present invention.

In the invention according to claim 1 or 2, the positional deviation of the screw bearing portion means one of displacement of the screw from its normal position in the axial direction and parallelism between the two screws, that is, eccentricity. Or both are meant.

[0012]

According to the clearance adjusting method of the twin-screw extrusion screw of the invention described in claim 1, the position deviation of the screw bearing portion, which is correlated with the eccentricity of the screw, is measured during the operation of the machine, and based on the measured value. Since the clearance between the screw flights is calculated, the clearance state can always be grasped.

Further, if there is a deviation between the clearance and the set value, that is, if there is an abnormality in the clearance, the position of the screw bearing portion is corrected to correct it. As compared with the conventional method of detecting an abnormality after that, quick control operation is possible, and there is no need to stop the machine to replace members such as screws, thereby improving product efficiency and machine operating rate.

In the clearance adjusting device for a twin-screw extruding screw according to the second aspect of the present invention, since the detecting portions each having a displacement sensor and a pressure sensor are used as means for measuring the positional deviation of the screw bearing portion, the clearance adjusting device can be promptly operated. And accurate measurement data can always be obtained.

Further, since a calculation unit having a function of setting a clearance, a function of receiving a signal from the detection unit and calculating a clearance and a function of calculating a deviation from the set value of the clearance is used, the signal from the detection unit is used. It is possible to immediately grasp the actual clearance value based on, and to know the degree of badness by comparing it with the set value.

Further, of the gear rotation shaft of the drive unit that cooperates with the screw bearing unit, that is, the gear rotation shaft equipped in the gear box, the rotation speed of the final stage is reduced to give the rotation power. Is attached to a gear rotation shaft directly connected to the screw bearing portion, and an oil compression device that can finely move the position of the gear rotation shaft, a displacement sensor that detects the position of the gear rotation shaft, a displacement sensor, and a calculation unit Since the control unit having the hydraulic pressure valve that adjusts the pressure and flow rate of the hydraulic oil supplied to the oil compression device according to the command is used, the position of the screw bearing unit can be indirectly corrected by adjusting the position of the gear rotation shaft. .

In general, by the cooperation of the above-mentioned detection unit, calculation unit and control unit, when an abnormality occurs in the clearance between screw flights, not only can it be corrected automatically and in real time, but it can also be set accurately. Even if the value is within the range or within the range, the actual clearance value and its deviation can always be known, and proper process control can be carried out.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method and apparatus for adjusting the clearance of a twin-screw extrusion screw according to the first and second aspects of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an adjusting apparatus of the invention described in claim 2 for carrying out the invention described in claim 1.

In FIG. 1, 1 is a cylinder,
A heating device (not shown) is attached to the peripheral wall. Two
Reference characters a and 2b are biaxial screws that are arranged in parallel in the cylinder 1 and that have flight portions 3a and 3b that rotate in different directions and mesh with each other. 4 is cylinder 1
Is a gear box arranged at the rear of the gear, which is driven by an unillustrated motor as a drive source to reduce the rotational speed to a required speed and finally to rotate the biaxial screws 2a and 2b in different directions. The group is built in.

Of the built-in gear group, 5a and 5b are
The gears are decelerated to give the final rotational speed, and the rotational power of the rotary shaft, which will be described later, is transmitted to the screw bearing portion, and 6a and 6b are the gear rotary shafts. The tips of the rotary shafts 6a and 6b are projected from the gear box 4 and are connected to the rear ends of the screws 2a and 2b by couplers 7a and 7b, and the projecting portions are screw bearing portions 8a and 8b.

9a and 9b are screw bearing portions 8a and
8b, the screw bearing portion 8 installed close to
It is a displacement sensor that detects the positions of a and 8b, and is a non-contact type that uses a semiconductor laser as a light source. The parallelism and axial deviation of the screw bearings 8a and 8b are always 0.5 μm accurate. It is measurable and detects the parallelism and the axial position of the screw bearing portions 8a and 8b, and the displacement converter 10 amplifies the detection signal and sends it to the arithmetic portion and digital display. .

Reference numeral 11 is a pressure sensor for detecting the pressure of the molten resin at the tip of the cylinder.
The pressure can be constantly detected via a pressure transmission pin (not shown) installed therein, and the pressure converter 12 amplifies the detection signal and sends it to the arithmetic unit, and digital display is also possible. A plurality of the pressure sensors may be installed to detect the average value.

Further, the pressure sensor 11 need not be installed if the action can be sufficiently taken by the detection of the displacement sensors 9a and 9b, and even if it is installed, it may not be operated. The displacement sensors 9a and 9b, the displacement converter 10, the pressure sensor 11, the pressure converter 12 and the like constitute a detection unit.

The arithmetic unit 13 is mainly composed of a controller composed of a microcomputer, and a storage device, an input / output device, etc. are attached to the controller, and the controller inputs the detection signal or data, which is input to the storage device by the input / output device, and the setting. It is equipped with a function to calculate the clearance from the measured value and the measured value, calculate the deviation between the clearance and its set value, and read the necessary instruction data for the control unit to be described later and send the command. Are stored together in the control box.

Reference numeral 14 is a power amplifier for amplifying the command from the arithmetic unit 13, and 15 is the amplified command, and the amplified data from a displacement sensor of the gear rotation shaft described later is converted into the pressure and flow rate of the hydraulic oil. Electro-hydraulic control valve,
6 is an operating oil pressure source, 17 is an oil compression device, which is connected to the rear end of the gear rotation shaft 6a, and hydraulic cylinders (not shown) divided into the left and right are operated individually or simultaneously to operate the gear rotation shaft 6a. It is configured to rotate in the forward and backward directions or to the left and right with the center of the rear end of the gear rotation shaft 6a as the rotation axis.

Reference numerals 18a and 18b denote gear rotating shafts 6a and 6b.
Is a contact type displacement sensor provided at the center of the rear end of each of the gears, operates within a range of 0.2 to 0.5 mm, and the position of the gear rotation shaft 6a is correctly changed by the operation of the oil compression device 17. Or not. The detection signal is amplified by the displacement converter 19 and sent to the electrohydraulic control valve 15. These power amplifier 14, electrohydraulic control valve 15,
Hydraulic pressure source 16, oil compression device 17, displacement sensor 1
A control unit is configured by 8a, 18b and the displacement converter 19.

Next, the adjusting method of the present invention according to claim 1 which is carried out by using the above apparatus will be described. When the extruder operates, the positions of the screw bearings 8a and 8b and the pressure of the molten resin at the tip of the cylinder 1 are detected by the displacement sensors 9a and 9b and the pressure sensor 11 in the detection unit. It is constantly in the monitoring state via the device 12 and is input to the arithmetic unit.

The calculation unit calculates the clearance between the screw flights 3a and 3b based on the signal from the detection unit, and if there is a deviation between the obtained clearance and the preset value, this deviation is calculated. In order to eliminate the above, a necessary command is read out and sent to the electrohydraulic control valve 15 via the power amplifier 14. The electro-hydraulic control valve 15 operates the oil compression device 17 based on the command, and finely adjusts the position of the gear rotation shaft 6a by the operation.

The fine movement condition is indicated by the displacement sensors 18a, 18
b is detected one by one, and the signal is the displacement transducer 19
If the data is sent to the electro-hydraulic control valve 15 via the, and the gear rotation shaft 6a has not changed its position as instructed, the electro-hydraulic control valve 15 has data that the position has been changed appropriately. The oil compression device 17 is operated until it is obtained.

Thus, the position of the screw bearing portion 8a is corrected in cooperation with the slight movement of the gear rotation shaft 6a. The corrected results are the displacement sensors 9a and 9b.
And the pressure sensor 11 will be checked. In this way, the clearance between the screw flights is always controlled in real time so as to maintain the initial set value.

The set value is not limited to one specific value, but may be a value having a constant width, that is, a range, and a value outside this range may be managed as an abnormal value. . In the above embodiment, the oil compression device is attached to the gear rotation shaft 6a, but it may be attached to the gear rotation shaft 6b.

[0033]

According to the clearance adjusting method of the twin-screw extrusion screw of the first aspect of the invention, the measured value of the displacement of the screw bearing portion closely related to the eccentricity of the screw and the pressure of the molten resin at the tip of the cylinder are measured. Since the actual clearance is calculated from this and the position of the screw bearing part is corrected to correct it, the process from abnormal clearance detection to corrective action is speeded up, and the quality is always excellent. The production method can be continuously produced easily, the product defect rate can be reduced to 1/4 or less of the conventional one, and the machine operation rate can be improved to 97 to 99%.

In the clearance adjusting device for a twin-screw extruding screw according to the second aspect of the invention, when the clearance between the screw flights is abnormal due to the cooperation of the detecting part, the calculating part and the controlling part, it is automatically and in real time. Not only can it be corrected accurately, but even if it is within the set value range, the deviation from the actual clearance can always be known, and proper process control can be carried out.
Therefore, the apparatus is suitable for use in the adjusting method according to the first aspect of the invention.

[Brief description of drawings]

1 is a claim for carrying out the invention according to claim 1;
It is a block diagram which shows one Example of the adjustment apparatus of the described invention.

[Explanation of symbols]

 1 Cylinder 2a, 2b Screw 3a, 3b Flight part 6a, 6b Gear rotation shaft 8a, 8b Screw bearing part 9a, 9b Displacement sensor 11 Pressure sensor 13 Calculation part 17 Oil compression device 18a, 18b Displacement sensor

Claims (2)

[Claims] 1. A displacement of a screw bearing portion of a twin-screw extruder having screws arranged in a cylinder and rotating in mutually different directions is measured, and a clearance between screw flights is calculated from the measured value. The two axes are characterized in that the clearance is obtained by comparing the obtained clearance with an initial set value and the deviation is corrected, and the clearance is controlled by correcting the position of the screw bearing portion so as to eliminate this deviation. Extrusion screw clearance adjustment method. 2. A detection unit having a displacement sensor for detecting a positional deviation of the screw bearing unit, setting a clearance between screw flights, calculating a clearance between screw flights based on a signal from the detection unit, the clearance and a set value. Of the oil compression device, which is attached to the calculation part that calculates the deviation from the control part and transmits the control command, and the gear rotation shaft of the drive part that cooperates with the screw bearing part and that can finely move the position of the gear rotation shaft. A displacement sensor for detecting a position; and a control unit having a hydraulic pressure valve for adjusting a pressure and a flow rate of hydraulic oil supplied to the oil compression device in response to a command from the displacement sensor and the arithmetic unit. Clearance adjusting device for twin screw.