JPH0475127B2 - - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for controlling the start-up conditions of an extruder, particularly a foamed plastic coating extruder.

(Technical background of the invention and its problems) Generally, in foamed plastic insulated wires,
Insulators are required to be foamed at a predetermined foaming rate in order to have insulation properties such as standard finished outer diameter and capacitance.

In the method of kneading and extruding foaming a resin containing a blowing agent using a coating extruder, a predetermined foaming rate cannot be obtained unless the resin temperature in the extruder is maintained at an appropriate value.

Conventionally, therefore, the product was not collected until the resin temperature, which had risen due to the shear heat generated during kneading after starting the extruder, had stabilized.

In other words, as shown in Figure 1, after the extruder is started with the heating temperature set to a steady value, the take-up speed of the extruded body and the rotational speed of the screw reach the steady value, and the resin temperature rises to the appropriate value. stable point
We started picking up products from T′.

Therefore, there was a problem in that it took a long time from starting the extruder to taking out the product, and a large amount of materials such as resin and conductors extruded during this time were wasted.

In addition, when the extruder is stopped and restarted, the residual resin that has been exposed to temperatures above the foaming temperature for a long period of time and has become overfoamed must be removed. This method resulted in a large amount of material loss.

(Object of the Invention) The present invention was made to solve these problems, and an object of the present invention is to provide a start-up control method for an extruder that can shorten the time from startup to product removal and reduce material loss. purpose.

(Summary of the invention) In the present invention, the heating temperature of the extruder is set in advance to a slightly higher value than the steady value, and the resin temperature in the extruder is rapidly raised by this set temperature signal, and at the same time, the rotation speed of the screw is increased. Extrusion is continued while increasing to a steady value at a higher rate of increase than the rate of increase in the take-up speed of the extruded body, and as soon as the rotational speed of the screw reaches the steady value, the set temperature of the extruder is returned to the steady value, and the resin temperature is This is a method for controlling the start-up of an extruder, which is characterized by maintaining the start-up at an appropriate value.

(Embodiments of the invention) Examples of the invention will be described below with reference to the drawings.

In the example, first, as shown in Figure 2C, the heating temperature setting value of the extruder is set slightly higher than the steady value within a range that does not cause over-foaming of the resin, and this set temperature signal is used to control the extruder heating temperature. The extruder is started while outputting to the heating kneading section. After startup, the temperature of the resin in the extruder rises rapidly in response to the set temperature signal, as shown in FIG. 2D, and further rises due to the shear heat generated during heating and kneading. In order to prevent this resin temperature from exceeding an appropriate value, the heating set temperature is returned to a steady value when it approaches the appropriate value.

In addition, the take-up speed of the extruded body after startup is controlled so that it increases at a constant speed as shown in Figure 2A, but at this time, the rotation speed of the screw is controlled so that the internal resin pressure does not become excessive. As shown in FIG. 2B in the range, the take-up speed is increased more quickly than the steady-state value. In this way, the resin temperature quickly rises to an appropriate value due to the generation of the shear heat.

In addition, as shown by the broken line in Figure 2B, the screw rotation speed can be controlled so that it is once raised to a value higher than the steady value and then lowered to the steady value when the take-up speed reaches the steady value. can.

In the embodiment controlled in this way, the time point T2 when the take-up speed reaches a steady value and the time point _T2 when the resin temperature reaches an appropriate value and product taking can be started.
can be made almost the same, and the time from startup to product removal can be significantly shortened.

(Effects of the Invention) As is clear from the above description, according to the present invention, the start-up time from the start of the extruder to the product removal can be significantly shortened compared to the conventional method, and the resin extruded at the time of start-up can be greatly reduced. can reduce material loss.

[Brief explanation of the drawing]

Figure 1 is a time chart showing changes over time in take-up speed, screw rotation speed, heating set temperature, and resin temperature when controlled by the conventional method;
The figure is a time chart showing the change over time of the same amount when controlled by the method of the embodiment of the present invention.

[Claims]

1 Arrange and fix a plurality of rod-shaped spacer members of an appropriate thickness in parallel at appropriate intervals on the surface of a sound-absorbing board such as a fiberboard, and integrally adhere the back side of the surface decorative board to these rod-shaped spacer members. A sound-absorbing decorative material characterized in that a slit-shaped opening is formed in a surface decorative board in a direction intersecting with a rod-shaped spacer member so as to penetrate between the front and back surfaces. 2. A process of installing a plurality of rod-shaped spacer members of appropriate thickness in parallel at appropriate intervals on the surface of a sound-absorbing board such as a fiberboard, and installing a surface decorative board on the surface of these rod-shaped spacer members. and integrally bonding the back side thereof to the surface of the rod-shaped spacer member, and forming a plurality of slit-shaped openings in the surface decorative board along the direction intersecting the rod-shaped spacer member using a router, a saw, etc. A method for producing a sound-absorbing decorative material, which comprises the steps of drilling a hole between the front and back surfaces, and separating the surface decorative material into an appropriate number of parts as necessary.