JPS6247696B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film thickness control method applied to a forming apparatus when forming a plastic film of uniform thickness using a polymeric material.

When a polymeric material is formed into a sheet-like material (hereinafter referred to as a film) by an extrusion film forming method, groups occur in the thickness of the film extruded from an extruder in both the longitudinal and width directions of the film. . In order to solve this thickness problem, a method of automatically correcting the thickness by changing the gap between the extrusion mouthpieces of the extruder has generally been attempted in the past. for example,
FIG. 1 shows a conventional automatic control device when a flat die is used as an extruder. As shown in the figure, the main parts of the flat die 1 are die bodies 2 and 3,
A chiyoke bar 4 for adjusting the gap and a retainer plate 5
, a plurality of adjustment bolts 6 and a heater 7
By rotating the adjustment bolt 6, the jaw bar 4 is moved and the gap w is adjusted. On the other hand, the automatic control section
A bolt drive device 8 that includes a chuck that can be attached and detached from the bolt and a drive motor (not shown) that rotates the chuck, and a rotation amount detector 9 that detects the amount of rotation of the adjustment bolt 6 rotated by the bolt drive device 8.
and a computer, a motor control device, a detection device for detecting the motor drive torque, etc. (not shown)
and a control panel 10 that commands the operations of the bolt drive device 8 and rotation amount detector 9.

In such an apparatus, the thickness distribution pattern in the width direction of the film extruded from the flat die 1 is measured, and the measured value is input into a computer (not shown) in the control panel 10. This computer compares the input measurement value with a preset and memorized film thickness setting value,
By calculating the deviation and detecting the position of the adjustment bolt 6 to be adjusted, determining the rotation direction and required rotation amount, and instructing the bolt drive device 8 and rotation amount detector 9 to operate, the chain yoke bar 4 is The gap w is automatically adjusted.

However, a mismatch occurs between the operation instruction signal for the adjustment bolt and the gap between the jaw bars that is actually adjusted. That is, the position of the adjustment bolt to be adjusted obtained based on the thickness distribution pattern signal in the film width direction, the rotation direction of the adjustment bolt, and the required rotation amount of the adjustment bolt. A phenomenon occurs in which the change in the gap and the actually adjusted change in the gap between the chuck bars do not match.

This is because the relationship between the amount of rotation of the adjustment bolt and the change in the gap between the jaw bars is not merely a linear relationship due to backlash of the adjustment bolt and other operating conditions. In other words, as shown in Fig. 2, there is a region (dead zone region) A in which the tooth bar gap w hardly changes even when the adjustment bolt is rotated, and a region (nonlinear region) B in which the change in the bolt rotation angle and the tooth bar gap w is not linear. This is due to the fact that there is a region (linear region) C in which there is a linear relationship between the bolt rotation angle and the jaw bar gap w. Therefore, even if the adjustment bolt 6 is rotated, the adjustment bolt 6 is in the dead zone area A.
If it is inserted into the hole, check the gap between the two
will hardly change, making it impossible to accurately adjust the tooth bar gap w.

In order to solve this problem, in the past, the necessary amount of rotation of the adjustment bolt was determined from the measured value of the film's thickness in the width direction, and based on that value, the adjustment by which the adjustment bolt was rotated was determined. Japanese Patent Application No. 49-23259 (Japanese Patent Publication No. 55-5413) proposes a method of detecting the rotational torque of the bolt and rotating the adjustment bolt by the necessary rotation amount, excluding the bolt rotation amount in the dead zone region of the adjustment bolt. .

This adjustment method uses a torque meter to detect the rotational torque of the adjustment bolt, and when the adjustment bolt is rotated according to the required rotation amount calculated based on the film thickness measurement, the rotational torque is detected with the torque meter. It is carried out while In other words, since the rotational torque of the adjustment bolt has the relationship A<B<C between the dead zone area A, nonlinear area B, and linear area C of the bolt as shown in Figure 2, the value of the rotational torque in the dead zone area A is Displayed as the lower limit value. Therefore, in the dead band area A between b and c in the figure, the adjustment bolt is rotated to point c while detecting the lower limit torque value with a torque meter, and the rotation amount in the dead band area A is calculated as the above-mentioned required rotation amount x ₁ + x ₂
By rotating the adjustment bolt by the required rotation amount x ₂ calculated above at point c, the gap w between the jaw bars is adjusted.

However, the conventional control method described above has the following drawbacks. Figures 3 and 4 are shown below.
This will be explained with reference to the figures.

FIG. 3 shows a plurality of adjustment bolts 6 ₁ to 6 ₆ arranged in a row.
It is an II sectional view in FIG. 1 showing the extruded state,
FIGS. 4a to 4e show the arrayed adjustment bolts 6 ₁ to _{6 6}
This shows the relationship between the In addition, in Figure 4,
4 indicates the position of the deformed jaw bar, L indicates the backlash (play) of the adjusting bolt itself, M indicates the flat position where the jaw bar is not deformed, and X ₁ and X ₂ represent the nonlinear regions B and B in Fig. 2. Linear region C
Adjustment bolt 6 corresponding to the required rotation amount x ₁ and x ₂
The amount of movement and u indicate the direction of movement of the adjustment bolt 6.

FIG. 4a shows an example of the state of each of the adjustment bolts 6 ₁ to 6 ₆ before adjustment. In this case, the adjustment bolts 6 ₂ , 6 ₃ , 6 ₄ , and 6 ₅ press the jaw bar 4 downward, and the adjustment bolts 6 ₁ and 6 ₆ press the jaw bar 4 upward.

Next, FIG. 4b shows a state in which the adjusting bolt ₆₃ has been rotated by x ₁ and moved upward by x ₁ . In this case, the yoke bar 4 moves upward by an amount corresponding to the change in the yoke bar 4 from point a to point b in FIG.

Further, when the adjusting bolt ₆₃ is rotated in the same direction as shown in FIG. 4c, the position falls between points b and c in FIG. 2, that is, within the dead zone area A, and the amount of movement of the yoke bar 4 does not change.

FIG. 4d shows a state in which the adjustment bolt ₆₃ has reached the end point of the dead zone area A, that is, point c in FIG. Further, when the adjustment bolt ₆₃ is rotated by x ₂ from point c, the chain bar 4 moves by x ₂ as shown in Fig. 4e, and from point c to d (nonlinear region B and The adjustment is completed by moving to the linear region C).

However, when adjusting only the adjustment bolt ₆₃ by rotating it from point a to point d in FIG. 2, the connection state between the other adjustment bolts ₆₅ and the jaw bar 4 changes to the fourth position, as shown in FIG. 4e. The jaw bar 4 changes from the downwardly pressed constraint state shown in Figures a to d to the released state. This is considered to be because, due to the number of adjustment bolts, the pitch of the bolts, the rigidity of the tie yoke bar, etc., when one adjustment bolt is adjusted, other adjustment bolts in the vicinity are affected.

Therefore, adjustment of one adjustment bolt causes an unexpected change in the coupling relationship between adjacent adjustment bolts and the tie yoke bar, resulting in a large change in the thickness pattern of the film and the occurrence of hunting. As a result, not only is time wasted until each adjustment bolt is properly adjusted, but the film product exceeds the set thickness tolerance, making it difficult to produce a film product with a uniform thickness within the standard. It was difficult.

Therefore, the present invention eliminates the above-mentioned drawbacks, and by stably adjusting the coupling relationship between each adjustment bolt and the jaw bar, it is possible to keep the film thickness within the set tolerance and to produce a film of uniform thickness. The purpose of the present invention is to provide a film thickness control method that enables the production of film.

Embodiments of the present invention will be described below based on the drawings. In this embodiment, a case will be described in which a flat die is used as the extrusion device, and the same parts as in the conventional example are given the same numbers, and redundant explanations will be omitted.

The film thickness control method of the present invention is based on the required rotation amount calculated by comparing the measured value of the width direction thickness pattern of the film formed so as to reduce the variation in film thickness with a preset thickness setting value. When rotating the adjustment bolt, the rotational torque of this adjustment bolt is detected by a torque detector, and if the adjustment bolt is adjusted passing through the dead zone region, the rotational torque is detected as the lower limit torque value. Control is performed so that the adjustment bolt is rotated over the entire lower limit torque value (within the dead band region) until the end point of the lower limit torque value, and the adjustment is completed regardless of the above-mentioned required rotation amount. Then, the thickness pattern in the width direction of the film is measured again, a new deviation is calculated, a new adjustment bolt to be adjusted and its required amount of rotation are set, and the same adjustment as above is repeated based on this required amount of rotation. Therefore, the gap between the jaw bars is adjusted.

Below, based on the conditions shown in Fig. 4 a to e, the fifth
This will be explained with reference to Figures a and b.

Figures 5a and 5b both show the relationship between the rotation amount of the adjustment bolt and its rotational torque, Figure 5a shows the case where adjustment of the adjustment bolt starts from point a within the linear region C, and Figure 5b is in the middle of dead zone area A (b ₁
(point). When the adjustment bolt is adjusted passing through the dead zone area A in this way, there are two possible adjustment starting points as shown in FIGS. 5a and 5b.

When the adjustment is started from point a in the linear region C as shown in _FIG . and x ₂ are obtained. If the adjusting bolt to be adjusted is the adjusting bolt ₆₃ in FIG. 4, the lower limit torque value of the adjusting bolt is set in advance on the torque detector, and
₃ is rotated by the required rotation amount x ₁ while detecting its rotational torque with a torque detector, the torque detector detects the adjustment bolt 6. The rotational torque of ₃ decreases toward the lower limit torque value and reaches the dead band region. It is displayed that point b of A has been reached (state shown in Fig. 4b). Furthermore, while detecting the lower limit torque value of the adjusting bolt ₆₃ with a torque detector, the bolt 63 rotates over the entire lower limit torque value range (within the dead band area A) to the end point c of the lower limit torque value.
The adjustment of the adjustment bolt ₆₃ is completed when point c is reached (the state shown in FIG. 4d). In this case, the adjustment is finished regardless of the required rotation amount x ₂ . Therefore,
At point c, the backlash L of the adjusting bolt ₆₃ is completely removed, so the coupling relationship between the adjusting bolt ₆₃ and the jaw bar 4 is stable as shown in Fig. 4d, and other nearby There is no adverse effect on the adjustment bolt.

On the other hand, when the adjustment is started from _one point b in the middle of the dead zone area A as shown in Fig. 5b, that is, when the lower limit torque value is displayed on the torque detector from the beginning, The amount of rotation y is obtained.
At that time, while detecting the lower limit torque value of the adjusting bolt ₆₃ with the torque detector,
The adjusting bolt ₆₃ is rotated over the entire range of the lower limit torque value until point c is reached, and the adjustment of the adjusting bolt ₆₃ is completed regardless of the above-mentioned required rotation amount y. In this case as well, the coupling relationship between the adjustment bolt ₆₃ and the tie yoke bar 4 is stable, and the neighboring adjustment bolts are not adversely affected.

When the adjustment of the adjustment bolt ₆₃ is completed in this way,
The thickness pattern of the film after adjustment is measured again, a new deviation is calculated, and the adjustment bolt to be newly adjusted, its rotation direction, and required rotation amount are determined. Next, adjust the adjustment bolt in the same way as above. By repeating this operation until the thickness pattern in the width direction of the film becomes uniform, the gap can be adjusted while the coupling relationship between the adjustment bolt and the tie yoke bar is stable.

Next, the results obtained using the method of the present invention will be explained based on FIGS. 6a to 6c, while comparing them with the conventional example.

FIG. 6a shows the data of the widthwise thickness pattern of the formed film, and FIG. 6b shows the measured data of the widthwise thickness pattern after being adjusted by the conventional method based on the data of FIG. 6a. , Figure 6c
3 shows measurement data of the thickness pattern in the width direction after adjustment using the method of the present invention. In the figure, m ₀ is the set value of the film thickness.

As shown in FIGS. 6a to 6c, when the data of the width direction thickness pattern as shown in FIG. The measurement data of the thickness pattern after the adjustment is as shown in Figure 6b, and a hunting phenomenon occurs in which thin parts become too thick and other parts become thinner, making it impossible to keep the thickness within the set tolerance. It becomes difficult. On the other hand, according to the method of the present invention, as shown in FIG. 6c, the hunting phenomenon does not occur, and the film thickness deviation is greatly improved and evened out. It can be accommodated.

In the above embodiment, only the case where the rotational torque of the adjustment bolt itself is used as the rotational torque value is explained, but the lower limit torque value is not limited to this. It is also possible to detect by employing a value that includes mechanical loss of equipment, etc.

As explained above, according to the present invention, the adjustment of the adjusting bolt is finished when the looseness of the adjusting bolt is removed, regardless of the required rotation amount, so that the coupling relationship between the adjusting bolt and the yoke bar is stabilized. Therefore, the hunting phenomenon does not occur and the adjustment time required for thickness control is reduced. In addition, it has become possible to easily keep the thickness of the manufactured film within the product tolerance, and it has also become possible to significantly improve the uniformity of the film thickness.

[Brief explanation of the drawing]

Figures 1 to 4 relate to the conventional example, Figure 1 is a schematic explanatory diagram of the automatic thickness control device, Figure 2 is a graph showing the relationship between the rotation amount of the adjustment bolt, the tooth bar gap and the rotational torque, and Figure 3 is a sectional view taken along the line I-I in FIG. 1 showing the arrayed adjustment bolts; FIG. 4a;
~e are explanatory diagrams showing the connection relationship between the adjustment bolt and the tire yoke bar in FIG. An example of the measurement data of the thickness pattern of the film is shown, FIG. 6b shows the measurement data after adjustment in the conventional method, and FIG. 6c is a diagram showing the measurement data after adjustment in the method of the present invention. be. In the drawing, 1 is a flat die, 2 and 3 are die bodies, 4 is a choke bar, 6, 6 ₁ , 6 ₂ , 6 ₃ ,
6 ₄ , 6 ₅ , 6 ₆ are adjustment bolts, A is the dead band area (the entire range of the lower limit torque value), B is the nonlinear area, C is the linear area, L is the play of the adjustment bolts, x ₁ , x ₂ , y are necessary It is the amount of rotation.

Claims (1)

[Claims] 1. Between multiple pieces: Measure the thickness of the sheet-like material extruded in the width direction using a polymer material molding device equipped with adjustment bolts, and compare the measured value with the preset thickness setting. The required amount of rotation of the adjusting bolt is calculated from the deviation obtained by comparing the values, and the adjusting bolt is rotated based on the required amount of rotation while detecting the rotational torque of the sheet-like object. In a film thickness control method for adjusting the thickness, when the rotational torque of the adjustment bolt decreases toward a preset lower limit torque value, a lower limit torque value is detected so that the variation in film thickness is reduced. From the time when the adjustment bolt is rotated over the entire range of the lower limit torque value, the adjustment of the adjustment bolt is completed regardless of the required rotation amount, and when the rotational torque starts from the lower limit torque value. The film thickness control method is characterized in that the adjustment bolt is controlled to be rotated until the lower limit torque value is reached and the adjustment is completed regardless of the required rotation amount.