JPH089194B2 - Inflation molding method and apparatus therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inflation molding method and apparatus. More specifically, the present invention relates to an inflation molding method and apparatus including a system for monitoring an extrusion rate.

[0002]

2. Description of the Related Art Inflation molding is suitable for forming a film tube, since melting, stretching and cooling of a thermoplastic resin material can be performed in a series of steps.
In order to perform this inflation molding, usually, a heating cylinder portion that heats and melts a thermoplastic raw material and rectifies and feeds it, and a melt that is connected and delivered to the downstream end of the cylinder portion are formed into a tubular shape. An inflation molding device comprising an inflation die for pushing out, a blower means for injecting hot air to the tubular melt extruded from the die, and a pinch roller portion for pulling out the film tube stretched by the hot air provided above the die is generally used. Has been done.

[0003]

The heating cylinder of the above apparatus is provided with a raw material inlet, a heater for melting the raw material, a screw for feeding the raw material, a rectifying filter, a die connecting adapter, etc. If molding is continued for a long period of time, screw abrasion, filter clogging, etc. will occur, which will reduce the extrusion rate with time, which will reduce the production rate and affect the quality. It is thought that this can be solved by monitoring the extrusion rate frequently, but until now, there is no system to directly monitor this, and at best, the extrusion rate is calculated from the daily production rate and checked. However, this is troublesome and lacks accuracy.

The problem to be solved by the present invention is as follows.
An object of the present invention is to provide a system capable of easily detecting a decrease in extrusion amount in real time in order to appropriately replace parts such as a screw and a filter so as not to impair the decrease in production amount and quality.

[0005]

Thus, according to the present invention, an inflation is performed in which the thermoplastic resin raw material supplied to the raw material feeding section is melted and discharged, and this is extruded from the die and hot air is jetted to stretch it into a film. In molding, the weight reduction amount per unit time or the consumption time per unit weight of the raw material supplied to the raw material feeding section is continuously monitored, and the weight reduction amount or the consumption time obtained by the monitor is determined by a predetermined number. Calculate and obtain the average value
Check whether each average value is within the preset tolerance range
Confirmed by monitoring the variation of the average value, thereby detecting the variation of the extrusion rate from the die based on the average value variation, the
Provided is an inflation molding method and an apparatus therefor, which issues an alarm when a value outside an allowable range is obtained .

[0006] The method of the present invention is carried out by a system for monitoring the fluctuation of the extrusion rate by the weight loss per unit time of the raw material supplied to the raw material feeding section of the heating cylinder or the consumption time per unit weight. Since the weight reduction amount per unit time (hereinafter referred to as a reduction rate) may include an error by chance, it is preferable to adopt the average value of the reduction rates in the method of the present invention. That is, it is preferable that the reduction rate is continuously measured and the obtained values are sequentially grouped by a predetermined number and the average value of each group is calculated and used. The above average value is preferably an arithmetic average value for simplifying the processing, but is not limited thereto. When the average value obtained as described above is plotted against the time axis, the variation over time is obtained, but it is possible to maintain an appropriate extrusion rate by maintaining this variation range within a certain appropriate range. it can. In other words, by monitoring the fluctuation of the average value, the average value deviating from the appropriate fluctuation range can be caught.

Therefore, the present invention also includes a heating cylinder portion for heating and melting a thermoplastic raw material and rectifying and delivering the same, and an inflation die for connecting the downstream end of the cylinder portion and for extruding the molten material to be delivered. An inflation molding apparatus comprising a blower means for injecting hot air into a melt extruded from the die, wherein a load cell disposed in a raw material charging part of the heating cylinder and a unit time from a weight change in the load cell An arithmetic processing unit that continuously calculates the weight reduction amount of the raw material per unit and sequentially averages the obtained continuous calculated values by a predetermined number, and an average value that is sequentially obtained by the arithmetic processing unit is set in advance. And a warning unit for detecting a value outside the permissible range in the comparison unit and notifying an abnormal extrusion amount. There is provided an inflation molding apparatus according to claim.

In the molding apparatus of the present invention, the load cell is arranged in the raw material charging section of the heating cylinder section, and the arithmetic processing section, which will be described later,
A configuration known in the art can be used except that the comparison unit and the alarm unit are provided. In the present invention, a load cell is arranged in the raw material charging section of the heating cylinder so as to detect the amount of decrease of the raw material stored in the raw material charging section. When the load cell is arranged, a raw material charging section is further provided above the raw material charging section, and the upper and lower limits of the raw material storage amount are set in the raw material charging section, and the upper and lower limits are set based on the signal from the load cell. It is preferable that the raw material is constantly supplied from the raw material feeding portion within the range so that the raw material can be smoothly fed to the heating cylinder portion. Regarding this configuration, for example, Japanese Patent Laid-Open No. 2-107426
It is possible to utilize the one disclosed in the issue. Further, the raw material charging unit may be provided with a measuring meter capable of displaying the raw material storage amount based on the output of the load cell.

The arithmetic processing unit of the present invention calculates the amount of change per unit time or the consumption time per unit weight (hereinafter referred to as a reduction rate) based on the signal output from the load cell, and each obtained calculated value. A predetermined number of (reduction rates) are stocked, the average value thereof is sequentially calculated, each obtained average value is sequentially stored, and a signal can be output to the comparison unit at the next stage. The comparison unit of the present invention can arbitrarily set the upper limit value and the lower limit value in advance, sequentially compares the signal from the arithmetic processing unit with the set upper limit value and the lower limit value, and is set by the upper limit value and the lower limit value. With respect to the signal deviating from the range, it can be output to the alarm means of the next stage. The alarm means of the present invention is provided with at least either a sound source or a display means, and is configured to be activated by a signal output from the comparison section.

The arithmetic processing unit further excludes, among the calculated values calculated from the output value of the load cell, those based on an accidental error and stocks a predetermined number from the next excluded calculated value and sequentially averages them. It is preferable to include an arithmetic control unit that can calculate the value. As the arithmetic control unit, for example, the upper limit value and the lower limit value can be arbitrarily set in advance,
A comparison unit that sequentially compares the signals for each reduction rate calculated by the arithmetic processing unit with the set upper and lower limits and outputs a signal that deviates from the range set by the upper and lower limits, When there is a signal output from the comparison section, stock switching means that can output the signal to the arithmetic processing section so as to start stock again from the next signal and calculate the average value.

[0011]

According to the present invention, the amount of reduction per unit time or the consumption time per unit weight (reduction rate) of the raw material stored in the raw material feeding section is continuously monitored. Next, the obtained reduction rate is calculated as an average value for each predetermined number. Next, it is confirmed whether each obtained average value is within a preset allowable range. When something deviating from this range is detected, the alarm means is activated, thereby notifying that the extrusion amount has changed. As a result, it is possible to know the appropriate replacement time for parts such as screws and filters so as not to impair the production quantity and quality.

[0012]

The present invention will be described in detail below with reference to the illustrated embodiments, but the present invention is not limited thereto. Example 1 FIG. 1 is a schematic view of an example of an inflation molding device of the present invention. In the figure, the molding apparatus is a raw material charging section.
(1), a heating cylinder part (2), an inflation die (3) connected to the downstream end of the cylinder part, and an air opening substantially upward around the melt extruded from the die. A blower means (4) for injecting hot air to the melt from a ring (not shown), and a pinch roller part (5) provided above the die for drawing the film molded product stretched by the hot air. There is. In addition, (6) is a width tube regulator, (7) is a control device,
(8) is a molded film. The raw material feeding section (1) is a first supply hopper (11) for directly supplying the raw material to the heating cylinder (2).
And a second supply hopper (1
2), a load cell (13) that manages the amount of raw material stored in the first supply hopper, and a shutter mechanism (14) that opens and closes the raw material supply cylinder that is hung from the second supply hopper based on a signal from the load cell. It is mainly composed. Load cell (13)
Controls the shutter mechanism (14) via the control device (7) to constantly store the raw material between the upper limit value and the lower limit value set in the first supply hopper (11), and It is configured so that the amount of raw material introduced into the heating cylinder part (2) from the first supply hopper (11) can be measured and output to the control device (7). The heating cylinder part (2) has a screw (22) driven by a motor (21), a straightening net (23), an adapter (24) for connecting to a die, and heating means (not shown), and the first supply The raw material dropped from the hopper (11) is heated and melted, and the raw material is rectified and sent to the die. The control device (7) has a CPU, and based on the output signal from the load cell (13), activates the shutter mechanism (14).
Operates and controls the extrusion rate of the melt extruded from the inflation die (3) in addition to the drive mechanism of the entire molding such as automatically adjusting the take-up speed at the pinch roller part (5), and notifies of this decrease in amount An extrusion rate control mechanism (71) is also installed.

The extrusion amount management mechanism (71) includes an arithmetic processing section (7
2), a comparison unit (73) and an alarm device (74). The arithmetic processing unit (72) has a built-in clocking means, calculates the amount of change per unit time (hereinafter referred to as a decrease rate) based on the output signal from the load cell, and obtains each calculated value (reduction rate). It is configured such that a predetermined number of stocks are stocked and the average value thereof is sequentially calculated, and each obtained average value is sequentially stored and can be output to the comparison unit (73). The comparison unit (73) has an input setting unit (not shown) that sets the upper limit value and the lower limit value in advance, compares the signal from the arithmetic processing unit with the preset upper limit value and the lower limit value, and the upper limit value and Alarm device (74) for signals that deviate from the range set by the lower limit
It is configured to output to. The alarm device (74)
A buzzer that operates by the output from the comparison unit (73) is used.

The operation of the inflation molding apparatus configured as above will be described. Prior to molding, the upper limit value and the lower limit value of the allowable range are set in the comparison part (73) in advance. The raw material stored in the first supply hopper (11) by driving the heating cylinder part (2) is
Inflation die (3) is introduced into the cylinder part, heated and melted, sent out, rectified and passed through an adapter.
Is extruded from. The melt extruded from the inflation die (3) is uniformly surrounded by the high temperature blower ejected from the air ring from the outside of the periphery and uniformly expanded into a film. Then, the product is passed through the width tube regulator while being taken up by the pinch roller at the tip thereof. While the molding apparatus is being driven, in the raw material feeding section (1), the thermoplastic resin raw material prepared in the second supply hopper (12) is supplied into the first supply hopper (11). At this time, by opening and closing the shutter mechanism based on the output signal of the load cell (13) via the control device (7), the raw material is always stored in the first supply hopper in a predetermined amount range. When the molding is started, the raw material reduction amount in the first supply hopper (11) is output to the arithmetic processing unit (72) of the control device (7) by the load cell (13). In the arithmetic processing unit (72), the load cell signal that is continuously output is sampled at a predetermined interval based on the time measuring means, the difference value between adjacent sampling values is calculated, and the difference value is stocked by a predetermined number each. The average value for the stock is calculated sequentially. The sequentially obtained average value is output to the comparison unit (73). In the comparison unit (73),
The sequentially input average value signals are compared with preset upper and lower limit values. In the above comparison, when the input average value signal exceeds the upper limit value or is lower than the lower limit value, it is output to the alarm device (74). The alarm device (74) is activated based on the output signal from the comparison unit (73), and it is notified that the extrusion amount from the inflation die (3) has changed. By the above operation, the extrusion amount from the inflation die is controlled within a predetermined range, and if this amount changes, an alarm device
It will be detected by (74).

Embodiment 2 FIG. 2 is a schematic view of another example of the inflation molding apparatus of the present invention. The molding apparatus shown in FIG. 1 is the same as that shown in FIG. 1 except that the control device (7) in the molding apparatus shown in FIG.
The device has the same configuration as that of the above-mentioned device, and therefore, the same members are denoted by the same reference numerals and the description thereof is omitted. The molding machine control device (7) includes a load cell signal monitoring unit (7) that monitors the sampled load cell signal value.
5) and an arithmetic processing control unit (76) for controlling the arithmetic processing unit (72) based on the output signal from the monitoring unit (75) are added. The load cell signal value monitoring unit (75) can measure the gradient of the load cell signal value with respect to the time axis from the difference value between the adjacent sampling values sampled and subtracted at predetermined intervals based on the time measuring means, and the predetermined gradient. You can enter a value, compare whether the measured slope value is within a predetermined range, and when a sampling value outside this is obtained,
It is configured to output to the arithmetic processing control unit (76). The arithmetic processing control unit (76), when there is an output from the monitoring unit (75), the arithmetic processing unit so as to start difference value calculation and stock again from the sampling value next to the deviated sampling value.
It is configured to activate (72).

The operation of the molding apparatus having the above structure will be described. Prior to molding, the upper limit value and the lower limit value of the allowable range are set in the comparison section (73) in advance, and the allowable range of the gradient value is set in advance in the load cell signal value monitoring section (75) of the control device (7). deep. After the above settings, the heating cylinder part (2) is driven and the first
The raw material stored in the supply hopper (11) is introduced into the cylinder portion, heated and melted, sent out, rectified, and extruded from the inflation die (3) through the adapter. The melt extruded from the inflation die (3) is a high temperature blower ejected from the air ring,
After being uniformly surrounded from the outside and expanded uniformly in the form of a film, it is air-cooled and hardened at its tip, and then taken up by a pinch roller at the tip of the tip, and made into a product through a width tube regulator. . While the molding apparatus is being driven, in the raw material feeding section (1), the thermoplastic resin raw material prepared in the second supply hopper (12) is firstly fed.
It is supplied into the supply hopper (11), but at this time, the control device
By the opening / closing drive of the shutter mechanism based on the output signal of the load cell (13) via (7), the raw material is always stored in the first supply hopper in a predetermined amount range. When the molding is started, the raw material reduction amount in the first supply hopper (11) is output to the arithmetic processing unit (72) of the control device (7) by the load cell (13). The arithmetic processing unit (72) samples the load cell signals that are continuously output at predetermined intervals based on the time measuring means, and calculates the difference value between adjacent sampling values. The difference value obtained at this time is compared with a preset gradient value in the load cell signal value monitoring section (75). On the other hand, the arithmetic processing unit (72) stocks a predetermined number of difference values obtained sequentially. When the load cell signal value monitoring section (75) determines that the sampling value deviates from the preset allowable gradient value, this is output to the arithmetic processing control section (76). Based on this output, the arithmetic processing control unit (76) operates the arithmetic processing unit (72) so as to clear the stocks up to then and start the difference value calculation and the stocks from the next sampling value. Except for the above gradient judgment, the extrusion rate from the inflation die is controlled in the same manner as in Example 1.

[0017]

According to the present invention, the extrusion amount can be accurately controlled in real time during inflation molding. From this, it is possible to properly detect the replacement time of the members such as the heating cylinder portion and the straightening net. Further, since the members can be appropriately replaced, maintenance of the molding apparatus can be favorably performed, and a molded product of constant quality can be produced with a constant production amount.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of an inflation molding device of the present invention.

FIG. 2 is a schematic view of another example of the inflation molding apparatus of the present invention.

[Explanation of symbols]

(1) ... Raw material charging section (2) ... Heating cylinder section (3)
Inflation die (4) Blower means (5) Pinch roller section (6)
Width tube regulator (7) Control device (8) Molded film (11)
First supply hopper (12) ... Second supply hopper (13) ... Load cell
(14) ... Shutter mechanism (21) ... Motor (22) ... Screw (23) ... Commutation net (24) ... Adapter (71) ... Extrusion amount management mechanism (72) ... Arithmetic processing section
(73) ... Comparison section (74) ... Alarm device (75) ... Load cell signal monitoring section (76) ... Arithmetic processing control section

Claims (3)

[Claims] 1. In an inflation molding in which a thermoplastic resin raw material supplied to a raw material charging section is melted and sent out, and this is extruded from a die and hot air is jetted to stretch it into a film shape, the material is supplied to the above raw material charging section. The weight reduction amount of the raw material per unit time or the consumption time per unit weight is continuously monitored, and an average value is calculated for each predetermined number of weight reduction amounts or consumption times obtained by the monitor, and each obtained average is obtained.
Check if the value is within the preset tolerance range
Monitoring the variation of the mean value each, as well as detecting the variations in the extrusion amount of the die based on the average value variation, the allowable range
An inflation molding method, which comprises issuing an alarm when a value outside the range is obtained . 2. A heating cylinder portion that heats and melts a thermoplastic resin material and rectifies and feeds it, an inflation die that is connected to a downstream end of the cylinder portion and that pushes out a molten material that is fed out, and the die. An inflation molding apparatus comprising a blower means for injecting hot air into a melt extruded from a load cell disposed in a raw material charging section of the heating cylinder section, and a weight change in the load cell per unit time. An arithmetic processing unit for continuously calculating the weight reduction amount of the raw material or the consumption time per unit weight and sequentially averaging the continuously calculated values obtained by a predetermined number to calculate an average value, and the arithmetic processing unit sequentially obtaining the average value. A comparing unit for comparing whether or not the average value is within a preset allowable range, and an alarm means for detecting a value outside the allowable range in the comparing unit and notifying an abnormal extrusion amount. An inflation molding device comprising: 3. The arithmetic processing unit compares whether or not the calculated value of the weight reduction amount per unit time or the consumption time per unit weight, which is continuously obtained, is within a preset allowable range, and When a value outside the allowable range is obtained, an arithmetic control unit for instructing the arithmetic operation unit to operate so that an average value of a predetermined number can be calculated from the next value is provided. 2. The molding apparatus according to 2.