JPS6135225A - Method of measuring position of corresponding die bolt - Google Patents

Abstract

PURPOSE:To enable to measure easily a position of a corresponding die bolt, by blowing air against predetermined positions corresponding to positions of the die bolts on the surface of a plastic sheet moving on the surface of a lip or directly below the lip of a T die from one or a plurality of pieces of nozzles. CONSTITUTION:Air is blown against a lip 11A of the lower part of a certain die bolt 13 out of a plurality of the die bolts 13 by facing a nozzle 32 toward the lip 11A during molding of a sheet 12 by working an extruder 21. The lip 11A is either cooled or heated by abutting a thin flow of the air blown off through the nozzle 32 against the lip 11A. A flow, therefore, of a polymer flowing through a T die 11, generally, is reduced in case of cooling and increased in case of heating, or hardness becomes hard in case of the cooling and soft in case of the heating, through which a thickness of a sheet 12A is varied. When a variation of the thickness is detected by a thickness meter 23, a position corresponding to the specific die bolt 13 can be discriminated on a plane of the sheet 12.

Description

[Detailed Description of the Invention] [Technical field to which the present invention pertains] The present invention provides a method for adjusting the die bolt of a T-die, which greatly affects the thickness of the plastic sheet, etc., when manufacturing a plastic sheet or film. , relates to a method for measuring the position corresponding to a die bolt on a sheet, etc. after molding.

[Prior art]

When molding a plastic sheet or film (hereinafter simply referred to as a sheet) using a T-die, it is necessary to adjust the gap between the die slits in order to make the thickness uniform. However, due to the neck-in phenomenon (a phenomenon in which the sheet width becomes narrower than the die slit width) between the T-die and the forming roll, when adjusting the gap between the T-die slits using a die port based on the results of measuring the sheet thickness, the sheet It is impossible to accurately determine the position of the die bolt in the width direction.

In Figure 1, the sheet 12 that has exited the T-die 11 is necked in to the position of the I-X cast roll (not shown).
F514 is an imaginary line indicating the neck-in state for each die bolt 13 position.

Note that the spacing between the 11 tables (3) is shown as being the same, but both sides may be narrower in some cases.

For this purpose, the sheet width can be divided equally by the number of die bolts, or the die slit gap can be adjusted appropriately based on representative data obtained by carefully comparing the l° islit gap with the sheet thickness and position. We have been making adjustments, but when the conditions are changed, the corresponding positions become distorted, and in extreme cases, the result is that the unevenness of thickness is even exacerbated, making it impossible to make correct adjustments.

Furthermore, the neck-in ratio is not constant due to differences in materials and operating conditions, making it even more difficult to know the corresponding position.

[Purpose of the invention]

The present invention has been made from this viewpoint, and its purpose is to easily and easily adjust the die bolt position corresponding to the position on the sheet at the manufacturing site even if the neck-in phenomenon changes due to changes in materials, operating conditions, etc. The object of the present invention is to provide a method for measuring without contact.

[Key points of the invention]

The method for measuring the corresponding die bolt position in the present invention is T&
Corresponds to the die bolt position on the surface of the plastic sheet, etc., which moves from one or more nozzles to the lip surface of T, Y-A, or just below the lip, for plastic sheets where neck-in phenomenon occurs between A and cast rolls. By blowing air at a predetermined position and cooling or heating the plastic sheet, etc., the thickness of the air x blown area is locally changed, and this change is detected by a thickness gauge to form a cast roll. l on the surface of the subsequent molded plastic sheet, etc.

The feature is that it measures the position corresponding to Evolt.

[Embodiments of the invention]

The present invention will be explained below with reference to FIG. 2 showing one embodiment. The extruder 21 melt-kneads the polymer into a melted state, which is then extruded from the T-die 11 and passed through the cast roll 22.
It is cooled and solidified and formed into a sheet. After leaving the cast roll 22, the f'LJE-shaped sheet 12 undergoes necessary treatment, passes through a thickness gage 23, and is then wound up into a product 25 by a winder 24.

Note that the measurement data of the thickness gauge 23 is normally displayed on the CRT 27 via the microcomputer 26.

In this process, the present invention is characterized in that air is blown from the nozzle 32 onto the 12 sheets directly below the lip IIA or lip 11A of the T-die.

The number of nozzles 32 is one or more (in this case, the interval is i
It can be held by hand, but is preferably mounted on a machine base (not shown) so as to be movable in the direction perpendicular to the plane of the drawing. The temperature of the air ejected from the nozzle 32 is normally sufficient at room temperature, but depending on the characteristics of the material, a cooler or heater 33 may be installed in front of the nozzle 32, or the nozzle 32 or cooler 33 may have air volume adjustment. A valve 34 is connected and further connected via an air hose 35 to an air supply (not shown).

Next, a case will be described in which only one nozzle 32 is used in the operation of the embodiment described above. While the extruder 21 is operating to form the sheet 12, the nozzle 32 is directed toward the lower 11 lug 11-A of one of the plurality of die bolts 13 (see Figure 1). Blow air.

The thin stream of air ejected from the nozzle 32 is the lip IIA.
etc. to cool or heat this area. Therefore, the flow t of the polymer flowing through the T-die 11 generally decreases in the case of cooling and increases in the case of heating, or becomes hard in the case of cooling and becomes soft in the case of di-heating. Thickness varies. If this thickness change is detected by the thickness gauge 23, the position corresponding to the specific die bolt 3 on the plane of the sheet 12 can be determined. , fx If there are two nozzles 32, positions corresponding to two specific i° die bolts 13 are determined, and if there are three nozzles 32, positions corresponding to three specific die bolts 13 are determined. .

FIG. 3 is a diagram showing the measurement results of the sheet 12 by the thickness gauge 23, where the vertical axis represents the thickness and the unit is microns, and the values on the horizontal axis are the same as the values for the ivolt 13 in FIG. This is the bolt number. The conditions of this diagram are fll, in which air heated by the heater 33 is ejected from the nozzle 32, and (2) indicates when the nozzle 32-(i- is not in use).
(B is when one nozzle 32 is placed below the die bolt 13 at position 2, O is when one nozzle 32 is placed below the die bolt 13 at position 3) When XAfc is placed below 3, ■ is one nozzle 32 and 4 are shown when placed below the die bolt 13 at position 4.

3 shows the case where three nozzles 32 are placed below the l° port 13 at positions 3 to 5.

〔Effect of the invention〕

As explained above, the method of measuring the corresponding die bolt position in the present invention is as follows: l) Air is blown to a predetermined position corresponding to the die bolt position on the lip surface of the T-die using one or more nozzles, and air is blown through the lip. By cooling or heating the sheet, the thickness of the air-blown portion is locally changed, and this change is detected by a thickness gauge to measure the corresponding position of the die bolt on the surface of the formed sheet after being cast rolled. . Therefore, with a simple configuration that does not contact the seat and blows air, it is possible to determine the position of the bolt with high accuracy despite the low cost.

[Brief explanation of drawings]

FIG. 1 is a plan view for explaining the neck-in phenomenon, FIG. 2 is a side view showing an embodiment of the present invention, and FIG. 3 is a diagram showing the thickness of a molded sheet.

Claims (1)

[Claims] For plastic sheets, etc. where a neck-in phenomenon occurs between the T-die and the cast roll, one or more nozzles correspond to the die bolt position on the surface of the plastic sheet, etc., which moves on the lip surface of the T-die or just below the lip. By blowing air at a predetermined position and cooling or heating the plastic sheet, etc., the thickness of the air-blown part is locally changed, and this change is detected by a thickness gauge, so that the thickness of the plastic sheet after the cast roll is A method for measuring a corresponding die bolt position, which measures a position corresponding to the die bolt on the surface of a molded plastic sheet or the like.