JP3213767B2 - Bank amount detection method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sheet forming of a plastic material, and more particularly to a method for detecting a bank amount in bank forming and an apparatus therefor.

[0002]

2. Description of the Related Art As shown in FIG.
A flat die 10 connected to, for example, an extruder is provided upstream of a gap 13 between two forming rolls 11 and 12 controlled to a desired temperature and rotated in the directions of arrows A and B in pairs.
Plasticized material 14 heated to a desired temperature and plasticized
And a pool of the plastic material 14 on the upstream side of the gap 13,
That is, the plastic material 14 forming the bank 14a is drawn into the narrowest gap 13 (hereinafter simply referred to as a gap) 13 by the rotation of the forming rolls 11 and 12 so that the plastic material 14 is formed. There is a method of carrying out pinching molding and carrying out the sheet 15 downstream of the gap 13.

One of the important factors that determines the quality of the sheet 15 manufactured by this sheet forming method is as follows:
The purpose is to keep the bank amount, that is, the height h of the bank 14a from the center of the gap 13 at an appropriate value. If the bank amount h is insufficient, a surface defect called “hike” occurs,
If the bank amount h is excessive, a surface defect called “bank mark” occurs, and furthermore, the forming roll 1
1 and 12 are deflected to deteriorate the thickness distribution of the sheet 15 in the width direction. In order to produce the sheet 15 having desired characteristics without causing such surface defects and deterioration of the thickness distribution, it is necessary to more accurately control the bank amount h.

Therefore, conventionally, as disclosed in JP-A-48-47955 and JP-A-53-28657, light is applied to the bank 14a from the upstream side or from the side to reflect or pass the light. Measure the bank amount h,
The flat die 10 is adjusted so that the bank amount h becomes a desired value.
Of the plastic material 14 from the material or the forming roll 1
Although apparatuses for controlling the rotation speeds of the first and the second have been proposed, it is difficult to accurately detect the bank amount h by these methods.

The present applicant has proposed a method described in Japanese Patent Application Laid-Open No. 3-161315 as a method for more accurately detecting the bank amount h. This method is based on the knowledge that the temperature of the sheet 15 carried out to the downstream side of the gap 13 is related to the bank amount h, and is already being put to practical use.

[0006]

The method of detecting the bank amount h based on the temperature of the seat 15 is being evaluated as a method capable of detecting the bank amount h more accurately. Is measured with a radiation thermometer, there is a disadvantage that a measurement error occurs when the absorption wavelength of infrared rays changes due to a change in the material or color of the sheet 15. Further, when a laminate film on which a pattern is printed is supplied from the non-winding side forming roll 11 to be laminated on the sheet 15, there is a disadvantage that a measurement error occurs due to a change in emissivity due to the pattern.

[0007] The present invention solves the above-mentioned problems,
It is an object of the present invention to provide a method and a device capable of easily and accurately detecting a bank amount.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method for forming a desired temperature at a position upstream of a gap between a pair of forming rolls which are arranged substantially in parallel and rotate at a desired temperature. A plastic material heated and plasticized is supplied, and the plastic material is pressed and formed into a sheet by the forming roll while forming a bank on the upstream side of the gap between the forming rolls, and is carried out to the downstream side of the gap. In the method for detecting the amount of bank in sheet forming, the surface temperature of the forming roll on the non-winding side of the sheet to be carried out of the pair of forming rolls is measured, and the surface temperature near the downstream side of the gap is measured. It is to detect the bank amount based on this.

It is preferable that the temperature information of the forming roll to be measured is a temperature distribution of at least a plurality of locations in the width direction of the forming roll.

In order to achieve the above object, the present invention provides a plasticizer which is heated to a desired temperature and heated at a desired temperature upstream of a gap between a pair of forming rolls which are arranged substantially in parallel and rotate at a desired temperature. The plastic material is supplied by the forming roll, and the plastic material is formed into a bank by forming the bank on the upstream side of the gap between the forming rolls. In the amount detection device, the radiation thermometer installed downstream of the gap, the radiation thermometer, of the forming roll of the non-winding side of the sheet to be carried out of the pair of forming rolls, It is installed toward the roll surface near the downstream side of the gap.

The radiation thermometer is preferably mounted so as to be able to scan in the width direction of the forming roll.
It is preferable to provide a reflecting plate facing the surface of the forming roll near the downstream side of the gap, which is the portion to be measured.

[0012]

The plastic material heated to a desired temperature from a flat die or the like connected to the extruder and plasticized and supplied to the upstream side of the gap between the forming rolls is lower than the temperature of the plastic material and is suitable for forming. While being cooled by the forming rolls controlled to the temperature, the rolls are drawn into the gap by the rotation of the forming roll, pressed and formed, and formed into a sheet and carried out downstream of the gap. The cooling of the plastic material by the forming roll is related to the bank amount h. In other words, the plastic material forming the bank is drawn into the gap by the surface of the forming roll due to the rotation of the forming roll and becomes a sheet, so the temperature of the plastic material reaching the gap depends on the contact time with the forming roll if the bank amount is large. Becomes longer and is cooled more. Conversely, if the bank amount is smaller, the degree of cooling becomes smaller. Therefore, the temperature of the sheet carried out from the gap is high when the bank amount is small, and is low when the bank amount is large.

By the way, the temperature of the forming roll is controlled to a desired temperature suitable for forming as described above, but a portion where the plastic material comes into contact receives heat from the plastic material and rises in temperature. The surface temperature immediately downstream of the gap of the forming roll on the non-winding side of the sheet, that is, the surface temperature of the portion where the sheet peels off, is higher when the bank amount is larger, and lower when the bank amount is smaller. Therefore, by measuring the temperature near the downstream side of the gap with a radiation thermometer, the bank amount can be detected without being affected by the emissivity of the plastic material.

[0014]

1 and 2 show an embodiment of the present invention.
This will be described with reference to FIG. In FIG. 1, a flat die 10
Is connected to an extruder (not shown), preferably via a gear pump (not shown), and is supplied with a plastic material 14 such as molten plastic or rubber.
Is controlled to a desired temperature by a heater (not shown), is formed into a sheet shape from the slit-shaped outflow portion 10a, and is supplied to the upstream side of the gap 13 between the forming rolls 11 and 12. In addition, 16 is a lip adjusting device, and 17 is a choke bar.

The forming rolls 11 and 12 are controlled to a desired temperature by flowing a temperature-controlled fluid into the inside thereof.
It is rotated at a controllable predetermined speed in the directions indicated by arrows A and B. The gap 13 can be controlled to an appropriate value by moving the forming roll 11 in the left-right direction in FIG. 1 by a gap adjusting device (not shown).

The plastic material 14 supplied in the form of a sheet to the upstream side of the gap 13 is so-called bank-formed by the two forming rolls 11 and 12 to form a sheet 15. The bank-forming itself is the same as a known one. Therefore, detailed description is omitted.

A radiation thermometer 21 is arranged on the downstream side (the lower side in FIG. 1) of the gap 13. Radiation thermometer 21
Is arranged to measure the surface temperature of the forming roll 11 on the side where the sheet 15 unloaded from the gap 13 is not wound, near the downstream side of the gap 13, that is, near the downstream side of the place where the sheet 15 is peeled off. I have.

The radiation thermometer 21 is mounted on a scanning head 24 that moves along a guide rail 23 provided on an apparatus frame 22. The guide rail 23 extends in parallel with the forming roll 11, and moves the radiation thermometer 21 along the gap 13 by moving the scanning head 24.

The output of the radiation thermometer 21 is supplied to the scanning head 24
The temperature information is taken out in association with the width direction position of the forming roll 11.

A reflection plate 25 is attached to the radiation thermometer 21 so as to face the measured point P of the forming roll 11 so that the heat radiation from the roll surface can be reflected as many times as possible in the vicinity of the point P. To suppress the incidence of thermal radiation.

Next, the method of detecting the bank amount according to the present invention will be described together with the operation of the present apparatus. The plastic material 14 heated and melted by an extruder (not shown) is preferably supplied to the flat die 10 at a desired flow rate controlled by a gear pump, and is controlled to a predetermined temperature by a heater (not shown) provided on the flat die 10. Discharged in sheet form.

The plastic material 14 discharged from the flat die 10 forms a bank 14a on the upstream side of the gap 13 between the forming rolls 11 and 12, and the gap 14 is formed by the drawing force of the forming rolls 11 and 12 generated according to the bank amount h. The sheet 15 is semi-forcibly pulled into the sheet 13, and is cooled and pressed by the forming rolls 11, 12 to form a sheet 15.

At this time, at least the forming rolls 11, 1
2 is controlled to a desired temperature suitable for sheet forming lower than the discharge temperature of the plastic material 14 discharged from the flat die 10 by, for example, passing a fluid controlled at a predetermined temperature. 12 plastic materials 1
The portion in contact with 4 is partially heated.

During the partial temperature rise of the forming rolls 11 and 12, the forming roll 11 on the side where the unloaded sheet 15 is not wound is located immediately downstream of the gap 13, that is, the sheet 15.
The temperature θ at the part where the is peeled off (approximately the point P to be measured)
As shown by the curve T in FIG. 2, there is a certain relationship that the larger the bank amount h is, the higher the bank amount h is.

The value of the temperature θ depends on the temperature of the plastic material 10 discharged from the flat die 10 and the forming rolls 11 and
Although it depends on the ambient conditions such as the temperature of No. 12, there is a certain relationship with the ambient conditions such as these temperatures. Therefore, the bank amount h can be detected by grasping the surrounding conditions and detecting the temperature θ at the location P.

The above ambient conditions include those that vary depending on the type of the plastic material 14 such as the specific heat and the thermal conductivity of the plastic material 14. The difference between the absorption wavelengths (including the color) is relatively small, and these numerical values are relatively accurately grasped for each material, so that the conditions can be easily set. Therefore, the detection of the bank amount h by detecting the temperature θ of the location P can be performed relatively easily and more accurately, and is not particularly affected by the color and pattern of the sheet 15 at all.

The sheet 15 carried out from the gap 13
When is wound around the forming roll 12, there is a case where peeling failure occurs with respect to the forming roll 11. In the initial stage of the occurrence of the peeling failure, the place where the sheet is peeled off from the forming roll 11 is repeatedly and slightly moved to the sheet discharge side.

This repetitive movement of the sheet peeling point appears as a change in the temperature θ of the measured point P of the forming roll 11. Since this repetitive movement has a shorter cycle than one rotation cycle of the roll and can be clearly distinguished from a change in the bank amount h, the occurrence of peeling failure should be detected early without adversely affecting the detection of the bank amount. Becomes possible.

In the above-described embodiment, the forming rolls 11, 1
Although the example in which the supply of the plastic material 14 to 2 is performed from the flat die 10 connected to the extruder has been described, the present invention is not limited to this, and can be applied to general bank molding without using the flat die 10. Needless to say, there is.

[0030]

As described above, according to the present invention, the influence of the material, color, pattern, and the like of the sheet can be reduced or eliminated, and the bank amount can be detected more simply and accurately. The effect that can be obtained is obtained, and further, the occurrence of the sheet peeling failure can be detected.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a forming roll surface temperature θ and a bank amount h at a measurement point P.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flat die 11, 12 Forming roll 13 Gap 14 Plastic material 15 Sheet 21 Radiation thermometer 23 Guide rail 24 Scan head 25 Reflector

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 43/22-43/34 B29C 43/52-43/58 B29C 47/78-47/92 B29C 59 / 04 B29D 7/00-7/01

Claims (5)

(57) [Claims] 1. A plastic material heated to a desired temperature and plasticized is supplied to an upstream side of a gap between a pair of forming rolls which are arranged substantially in parallel and rotate at a desired temperature, respectively. And forming a bank on the upstream side of the gap between the forming rolls by the forming rolls. Measuring the surface temperature near the downstream side of the gap of the forming roll on the non-winding side of the sheet to be carried out, and detecting the bank amount based on the measured temperature information. Detection method. 2. The method for detecting a bank amount according to claim 1, wherein the temperature information of the forming roll to be measured is a temperature distribution of at least a plurality of positions in a width direction of the forming roll. 3. A plastic material heated to a desired temperature and plasticized is supplied to an upstream side of a gap between a pair of forming rolls which are arranged substantially in parallel and rotate at a desired temperature, respectively. A sheet forming device for forming a bank on the upstream side of the gap between the forming rolls by using the forming roll, and carrying out the sheet to the downstream side of the gap. The radiation thermometer is installed on the non-winding side of the pair of forming rolls of the unwound side of the sheet to be conveyed, toward the roll surface near the downstream side of the gap. An apparatus for implementing the bank amount detection method according to claim 1, wherein the apparatus is installed. 4. The apparatus according to claim 3, wherein the radiation thermometer is mounted so as to be able to scan in the width direction of the forming roll. 5. The apparatus according to claim 3, wherein a reflecting plate is provided so as to face a forming roll surface near a downstream side of the gap, which is the portion to be measured.