JPS6350179B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting the thickness unevenness in the width direction of a plastic film, sheet, etc., and in particular, the lip gap adjustment of a die for discharging the film, etc. is performed using a slide lip or a chuck bar (hereinafter referred to as a slide lip method). (explained).

As shown in FIGS. 1 and 2, the T-die using the slide lip method is moved along the slide surface A of the movable die 14 by a die bolt 13 having a plurality of slide lips 12 in the width direction relative to the fixed lip 11. The gap 15 is adjusted.

However, the slide lip 12 is continuous in the width direction, and when a particular bolt among the multiple die bolts is operated, not only the lip gap at the position where that bolt acts changes, but also affects other parts. It has been found that
This phenomenon is called mutual interference effect.

For example, as shown in Figure 3, if only the 5th die bolt is operated, if only the 7th die bolt is operated, or if the former and the latter are operated at the same time, graphs a, b, and c will appear, respectively. Therefore, the "principle of superposition" does not hold.

Therefore, even if the target shape of the lip gap is known, it is extremely difficult to calculate the amount of bolt operation to achieve it, whether manually or automatically.

Currently, most of the adjustment of the lip gap is done manually based on the experience and feeling of the operator, so there are individual differences, which not only limits the ability to adjust the lip gap, but also takes a lot of time. hanging,
There were drawbacks such as the work being dangerous.

In addition, although some models have automated this adjustment, they have essentially been unable to solve the above-mentioned mutual interference effect, and the accuracy of the lip gap has been at a low level.

The present invention was developed by focusing on the fact that the system composed of the die bolt and slide lip is clearly a spring system, although it undergoes complicated deformation due to mutual interference effects. To provide a method for automatically adjusting the lip gap with high accuracy. To explain the method of the present invention in more detail, the thickness in the width direction of the sheet, etc. being formed is measured, and it is inspected whether the sheet thickness is a predetermined thickness, and if it is not the predetermined value, provides a lip gap adjustment method that calculates the above-mentioned mutual interference effect, automatically operates a die bolt for slide lip adjustment based on the result, and corrects the lip gap to a predetermined sheet thickness. It is to be.

Next, referring to FIG. 4, a plastic sheet according to an embodiment of the present invention will be explained using an example. Reference numeral 21 is a die attached to an extruder (not shown), and as explained in the above-mentioned conventional example, the die 21 is inserted in the width direction of the slide lip 21a. The lip gap is adjusted by pushing and pulling a plurality of die bolts 21b attached to the slide lip 21a to move the slide lip 21a relative to the fixed lip 21c.
A running sheet 22 passes through a cooling roller 23 and is wound up by a winding device (not shown) through a treatment process 24 that performs stretching and the like. 2
Reference numeral 5 denotes a thickness measuring device that continuously measures the thickness of the sheet 22 while it is running in the width direction. 26
is a calculation device that calculates the operation amount of each die bolt from the thickness in the width direction of the sheet measured by the measuring device 25. 27 is an A/D converter, and 28 is a storage setting device for storing and setting data necessary for various calculations performed by the calculation device 26 from an input device (not shown), such as a keyboard. 28a
28 is a target sheet thickness setting section that sets the sheet thickness at a plurality of predetermined locations in the width direction of the die 21;
b is a proportional constant (spring constant or A spring constant setting section 28c sets the reciprocal K) and the spring constant of a single bolt, and 28c is a constant setting section that sets the bolt gap l at both ends in the width direction of the slide lip 21a and the pitch a of a plurality of bolts. This is to set the constant when it is considered as a continuous beam with both ends fixed. 29 compares the sheet thickness value m _i detected by the thickness measuring device 25 and the value t _i set in the target sheet thickness setting section 28a, and determines the amount of lip gap to be changed from the deviation value e _I. It is a comparator that Reference numeral 30 denotes a calculation section that calculates the amount of change in each die bolt at the plurality of predetermined locations from the amount of change in lip gap received from the comparator 29 and the proportionality constant set in the spring constant setting section 28b. Reference numeral 31 denotes a calculation unit that calculates the amount of bending change ε _i due to bending of the slide lip 21a from the deviation value e _i calculated by the comparator, the constant l set in the constant setting unit, and a. 32
is a die bolt operation amount calculation unit that calculates the operation amount of each of the plurality of die bolts 21b from the results from the calculation units 30 and 31 and the constant set in the spring constant setting unit 28b, and this calculated value δ _i via the D/A converter 33, the CRT device 34a,
Printer 34b or floppy disk 34
c etc. to the recording unit 34, and also to the die bolt 21b via the power control unit 35.
The signal is applied as a feedback signal to the drive unit.

The system is configured as described above, and next, regarding its operation, the target thickness of the sheet at a predetermined location t _i
Assuming that the measured value of the sheet is m _i , the comparator 29 calculates the deviation e _i of each lip at a predetermined position as e _i =m _{i -ti} .

In general, if the bending displacement ε _i at each point of the lip is the amount of change Δp _i in each bolt load, then according to Hook's law, ε _i = _o-1 〓 ^j=1 f _ij , Δp _j (i=2, 3, 4...n -1)
(1) holds, and f _ij in equation (1) is a proportionality constant (path number of a spring constant) for the lip gap at the i-th position with respect to the j-th bolt load.

That is, ε ₂ =f _2.2 Δp ₂ +f _2.3 Δp ³ +f _2.4 Δp ₄ + …+f _2.o-1 Δp _o-1 ε ₃ =f _3.2 Δp ² +f _3.3 Δp ³ +f _3.4 Δp ₄ + …+f _{3.o- 1} Δp _o-1 ε ₃ =f _4.2 Δp ² +f _4.3 Δp ³ +f _4.4 Δp ₄ + …+f _4.o-1 Δp _o-1 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ ---
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
ε _o-1 =f _o-1.2 ′∆p ² +f _o-1.3 ′∆p ³ +f _{o-1.4 ′} ∆p ₄ +…+f _o-1,o-1 ′ ∆p _o-1 , and we can write a multidimensional simultaneous linear equation for ∆p _j . By solving, Δp ² , Δp ³ , Δp ⁴ Δp _o-1 can be found.

On the other hand, as shown in Fig. 5, the displacements ε ₁ and ε _o at both end positions of the slide lip become ε ₁ = ε _o = 0 when considered as a continuous beam with both ends fixed, and each point as shown in the lip displacement pattern in Fig. 6. The deviation ε _i at each position considering the bending displacement ε _i of is expressed by the following equation (2).

e _i = e ₁ + en-e ₁ / lx _i + ε _i (2) where x _i = (i-1) a and a is the bolt pitch,
l=(n-1)a is the distance between the bolts at both ends.

The amount of change Δp ¹ and Δpn in the bolt load at both ends is determined from the force balance equation: Δp ₁ +Δp _o + _o-1 〓 ^j=1 Δp _i =0 (3) From the moment balance equation: Δpnl+ _o-1 〓 ^j=1 Δp _i (i-1)a=0 (4) and can be obtained from this two-dimensional linear equation. Therefore, the operating amount δ _i of each die bolt can be obtained from the following equation (5): δ _i =e _i +Δp _i /K (5) (K is a spring constant in units of bolts).

The present invention will be explained according to the flowchart of FIG. 7 regarding this operation.The target sheet thickness setting section 28 sets the target sheet thickness pattern _ti , the spring constant setting section sets the proportional constant speeds _tij and K, and the constant The bolt spacing l and bolt pitch a at both ends are set in the setting section, the sheet measurement value pattern m _i is measured by the thickness measuring device 25, and the deviation pattern e _i = m _i −t _i is calculated by the comparator 29. Then, the calculation unit 30 calculates the bolt load change amount Δp _j . At the same time, the calculation quantity 31 calculates the bending displacement pattern ε _i from equation (2) using the deviation pattern e _i =m _i −t _i and l, a from the constant setting section 28c, and from both values Δp _j and ε _i . The calculation unit 32 calculates the bolt operation amount δ _i =e _i +Δp _i /K.

As is clear from the above equation, the die bolt operation amount ε _i determined by the present invention is determined by the first term serving as the reference, that is, the target displacement amount e _i of the movable cap, and the second term determining the correction amount.
It is expressed as a term, that is, the sum of elastic deformation amounts Δp _i /k of the bolt itself due to load changes, and there is no ambiguity at all.

As explained above, the bolt operation amount δ _i is determined and can be guided by the arithmetic unit 26 to the display device 34a using a cathode ray tube or the printer 34b. Also, power control unit 3
5, it is possible to provide feedback to the operating bolt drive unit, such as a heat bolt type or servo motor type, using thermal displacement, to achieve a predetermined lip gap, and there are individual differences in the adjustment work listed at the beginning. and defects that make the work dangerous are eliminated.

In addition, although the above explanation was about the slide-rip type T-die, not only the lip part but also
It is also applicable to a method in which the resin flow rate is adjusted by a choke bar provided in the resin flow path of the T-die.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing a slide-rip type T-die. FIG. 2 is a sectional view seen from the direction of arrow Z in FIG. FIG. 3 is a graph explaining the relationship between the operating bolt and lip displacement. FIG. 4 is a diagram showing one embodiment of the present invention. FIG. 5 is a diagram illustrating the displacement of a lip due to a continuous beam fixed at both ends. FIG. 6 is a diagram showing the displacement pattern of the lip. FIG. 7 is a flowchart showing the control process according to the method of the present invention. 21...Sliding lip die, 25...Thickness measuring device, 26...Calculating device, 28...Memory setting section, 29
... Comparator, 30, 31, 32... Arithmetic section, 34... Recording section, 36... Power control unit.

Claims (1)

[Claims] 1. The pattern of the flow path gap formed by the sliding lip or jaw bar and its opposing member is adjusted by pushing and pulling a plurality of die bolts provided in the width direction of the sliding lip, etc. In a method for adjusting the thickness of a plastic film or sheet, etc., molded by the T-die constructed as described above, in the width direction, the thickness of the film, etc. being molded is measured in the width direction, and the thickness is measured in advance at a plurality of predetermined locations. Compare the thickness t _i of the film, etc. in the width direction determined as a target, determine the target dimension of the lip gap to be changed from the deviation e _i = m _i - t _i , and then determine the amount of bending change ε _i of the slide or jaw bar. e _i =e _i +
Calculated from e _n −e ₁ /lx _i +ε _i [However, x _i =(i−1
) a, a is the bolt pitch, l = (n-1) a is the distance between bolts at both ends] and a proportionality constant of a plurality of die bolts for lip gap adjustment provided at positions corresponding to the target dimensions and the predetermined locations. From f _ij (spring constant or its reciprocal), the load change ΔP _i of the die bolt is ε _i = _n-1 〓 ^j=1 f _ij・Δp _j (i=2, 3, 4...n
-1), and from the above values Δp _i and ε _i and the spring constant K of the bolt alone, the operation amount of each bolt δ _i = e _i +
A method for adjusting the thickness of a plastic film or film, etc. formed by a slide type lip or choke bar type T-die, characterized in that the thickness is determined as Δp _i /K.