JPH0371825A - Method and apparatus for detecting foaming pressure in foam molding machine - Google Patents

Abstract

PURPOSE:To detect foaming pressure by transforming a force acting in the opening direction of a mold caused by a foaming pressure of a foaming synthetic resin material in the mold to a positional signal by means of a position detecting device, performing feedback thereof to a servo control part and transforming a torque generated by controlling a servo motor under a condition where a distance between molds is kept const. to an electric voltage. CONSTITUTION:A raw material bead of a foamable synthetic resin e.g. a foamable polystyrene is filled in a molding space 15 of a mold for foam molding and a process consisting of heating, foaming and cooling is performed. In this time, a position of a movable mold 5 is detected by means of a position detecting device 11 and it is transformed to a position pulse, which is fed back to a servo control part 12. The servo control part operates the difference between a pulse at a standard position and a pulse at a detecting position to obtain the deviation and furthermore it determines a speed control command based on this position loop gain and other transmitting function and controls a servo motor 9 so as to make the deviation zero. In this case, it is possible to detect a foaming pressure by transforming it to an electric voltage and detecting by means of a torque detecting device 13 of the servo motor 9.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a method and device for detecting the foaming pressure of a raw material in a mold in a foam molding machine that produces molded products using a foamed synthetic resin material. It is related to.

[Conventional technology]

When creating molded products using foamed synthetic resin materials such as foamed polystyrene, a pair of foam molding molds is closed, raw material beads are filled into the molding space, and the following steps are performed: heating and foaming, cooling, mold opening, and molding. The process of taking out items is performed sequentially.

At this time, the raw material beads that have been pre-foamed and filled in the mold are heated by steam, thereby generating an expansion force called foaming pressure, which, together with the rise in temperature, fuses together.

When this fusion is completed, cooling is performed, the mold is opened, and the molded product is taken out.

The foaming pressure of the foamed synthetic resin material in the mold increases as heating progresses and decreases as it cools.If the molded product is taken out when the foaming pressure is above a certain value, it will deform due to its own residual foaming pressure. , it is necessary to allow sufficient cooling time.

In addition, in the heating step, it is necessary to take a heating time so that the foaming pressure is at least a certain value so that sufficient fusion is achieved.

Usually, each step in foam molding is controlled by a timer, and heating and cooling steps are also performed based on the time set in this timer.

Another method is to attach a pressure sensor to a foam mold to directly measure the foaming pressure inside the mold, and control the heating, cooling, and mold opening processes based on this.

For example, in the technique disclosed in Japanese Utility Model Application Publication No. 57-90820, a pressure sensor is incorporated into a filler for filling raw materials to detect the foaming pressure in the mold.

Furthermore, Japanese Patent Application Laid-Open No. 59-230730 discloses that a pressure sensor is provided in an eject bin for ejecting a molded product to detect the foaming pressure in the mold.

[Problem to be solved by the invention]

If a timer is used to remove the molded product from a foam molding machine, the set cooling time may not be sufficient.
If the molded product is removed while the foaming pressure is still high, the molded product will be deformed due to the remaining foaming pressure, as described above.

For this reason, it is necessary to set a sufficient cooling time for the timer, which may result in unnecessary cooling, lengthening the cycle time and reducing work efficiency.

In addition, in the heating process, sufficient fusion will occur if the foaming pressure increases to a certain value, and there is no need to heat any further.

Even if heating is performed further than that, the quality will improve to some extent, but the quality will be higher than necessary, and additional cooling time will be required, resulting in a longer cycle time.

In other words, even in the heating process, time control using a timer is wasteful and reduces work efficiency.

In addition, mounting a pressure sensor on the mold requires work, and even if a pressure sensor is incorporated into the filler or eject bin as described above, the filler or eject bin will become larger. This includes problems such as making installation difficult and impairing the original function.

Furthermore, the foaming pressure that can be detected by a sensor provided in the mold is limited to the position of the sensor, and it is impossible to detect the entire foaming pressure.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a method and apparatus for detecting the foaming pressure of a foamed synthetic resin material filled into a mold of a foam molding machine.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a fixed formwork fixed to a foam molding machine main body and to which one of the molds for foam molding is attached, and a fixed formwork movable in opposition to the fixed formwork. can be,
A foam molding machine having a movable formwork to which the other mold of the foam molding mold is attached, and a servo motor that moves the movable formwork opposite to the fixed formwork, a position detection means for a movable mold to be attached; a servo control section that controls the servo motor based on the feedback of a position signal detected by the position detection means; and a servo control section that converts the torque of the servo motor into voltage. A torque detection means is provided, and after the foam molding mold is closed, a minute gap is created between the two molds, and the foaming pressure acting in the direction of increasing the distance between the two molds during foam molding is detected at the position. The foam molding process is performed while the servo motor is controlled to maintain the minute gap constant, and at the same time, the torque of the servo motor is detected by the torque detection means and fed back to the servo control unit. This invention discloses a foaming pressure detection method in a foam molding machine that detects foaming pressure by converting it into .

Further, in the present invention, there is provided a fixed formwork which is fixed to the main body of the foam molding machine and to which one of the molds for foam molding is attached, and which is movable opposite to the fixed form frame, and the mold for foam molding is A foam molding machine having a movable formwork to which the other mold of the mold is attached, and a servo motor that moves the movable formwork opposite to the fixed formwork, the movable mold being attached to the movable formwork. a servo control section that controls the servo motor based on the feedback of a position signal detected by the position detection means; and a torque detection means that converts the torque of the servo motor into voltage. This constitutes a foaming pressure detection device in the foam molding machine provided.

[Effect]

The method and device for detecting foaming pressure in a foam molding machine according to the present invention are as described above, and the force acting in the direction of opening the mold is detected by the position detecting means according to the foaming pressure of the foamed synthetic resin material in the mold. The foaming pressure is detected by converting the signal into a signal and feeding it back to the servo control unit, controlling the servo motor while keeping the distance between the molds constant, and converting the generated torque into voltage.

〔Example〕

The details of the present invention will be explained based on illustrated embodiments.

FIG. 1 is an explanatory view of the main parts of a foam molding machine body used in the present invention.

1 in the figure is a fixed formwork attached to the foam molding machine main body,
One of the fixed molds 3 of the foam molding molds 2 is attached thereto.

A filler for filling raw material beads and an eject bin (none of which are shown) for taking out a molded product are attached to the back side of the fixed mold 3.

Reference numeral 4 denotes a movable formwork that is movable in opposition to the fixed formwork 1, and the movable formwork 5 is the other of the foam molding molds 2.
is installed.

This movable formwork 4 is usually guided by tie bars (not shown) that are erected from the fixed formwork 1 to move.

The movable formwork 4 is moved by a moving means 6 that converts rotational motion into linear motion, and this moving means 6 includes, for example, a ball screw shaft 7 whose tip is attached to the back of the movable formwork 4 and this ball screw shaft. 7 and a ball napft 8 which is screwed together.

Reference numeral 9 denotes a servo motor attached to the main body of the foam molding machine, and the rotational force of this servomotor 9 is transmitted to the ball napft 8 via the belt IO, but the method of transmitting the rotational force is not limited to this.

FIG. 2 is a simplified block diagram for explaining the main parts of the present invention.

That is, the 90 rotations of the servo motor are converted into a position signal by the position detection means 11 such as a rotary encoder, and thereby the position of the movable formwork 4 can be detected.

The position detection means 11 can also directly detect the position of the movable formwork 4 using an optical encoder, a magnetic scale, etc., and one that determines the home position pulse and detects the subsequent change in the increase pulse is used. It is something.

The position of the movable formwork 4 detected by the position detection means 11 is converted into a position pulse signal and fed back to the servo control section 12.

The servo control unit 12 has a set reference position and a position detection means 11.
The servo motor 9 is controlled by a transfer function determined to correct the deviation by determining a deviation from the device signal consisting of the following.

Reference numeral 13 denotes a torque detection means that converts the torque of the servo motor 9 into voltage and detects it, and a direct current or alternating current tachometer generator, an optical encoder, or the like is employed.

Reference numeral 14 denotes a torque monitor, which allows the torque of the servo motor 9 detected by the torque detection means 13 and converted into voltage to be visually observed with an indicator or the like.

FIG. 3 is an explanatory cross-sectional view of the foam molding mold 2. FIG.

That is, the foam molding mold 2 has a fixed mold 3 and a movable mold 5, which form a molding space 15 when the molds are closed together.

At this time, on the joint surface of the fixed mold 3 or the movable mold 5,
A packing 16 made of an elastic body such as a ring is attached, and when the fixed mold 3 and the movable mold 5 are brought into complete contact, the packing 16 is compressed and elastically deformed.

Normally, this packing 16 has a diameter of about 6 to 8 m1, is buried in a groove with a depth of about 5 to 6 m provided on one side of the mold 2, and has a diameter of about 6 to 8 m1. ~2n
The degree of this is outstanding.

For this reason, from a state where the mold 2 is completely in contact, it is necessary to
Even when the 0 μm mold is open, the molding space I5 forms a closed space necessary for foam molding, and the packing 16 is elastically deformed and tightened by the torque of the servo motor 9 due to the force P. An elastic force E is generated in the opposing direction.

Further, the foamed synthetic resin raw material beads filled in the molding space 15 are heated, thereby generating a foaming pressure F in a direction that resists the tightening force P.

Therefore, if a minute gap is created in the foam molding mold 2 and the servo motor 9 is controlled to keep this gap constant, the tightening method P by the torque of the servo motor 9 will be The foaming pressure F of the foamed synthetic resin and the elastic force E of the packing 16 are always balanced.

FIG. 4 is a flowchart of the present invention.

First, drive the servo motor 9 to move the movable formwork 4,
The foam molding mold 2 is brought into complete contact.

The position of the movable mold 5 at this time is assumed to be Xo=O.

Next, the movable mold 4 is moved to create a minute gap between the fixed mold 3 and the movable mold 5.

This minute gap is, for example, 10I! The gap is about m, which is enough to maintain the elastically deformed state of the gasket 16 shown in FIG. 3.

If 100 pulses of the position pulse signal Xref are required to set this minute gap to 10 μm, then
Let ref = 100 (pulse).

In this state, raw material beads of a foamed synthetic resin (for example, foamed polystyrene or the like is used) are filled into the molding space 15 of the foaming mold 2, and heating, foaming, and cooling steps are performed.

At this time, the position of the movable mold 5 is detected by the position detection means 11, converted into a position pulse X, and fed back to the servo control section 12.

The servo control unit 12 generates a reference position pulse X ref (・
100 (pulse)) and the detected position pulse X to find the deviation α, and then determine the speed control command based on this position loop gain G6 and other transfer functions so that the deviation α becomes 0. Controls the servo motor 9.

At this time, the torque of the servo motor 9 is detected by the torque detection means】3
The bubbling pressure can be detected by converting it into a voltage and detecting it.

That is, if the servo motor 9 is controlled so that the micro gap of the foam mold 2 is maintained at 10 μm, the elastic force E by the packing 16 and the foam table If7. The sum of the foaming pressure F of the resin and the tightening force P by the torque of the servo motor 9 are always balanced.

Therefore, the foaming pressure F is expressed as F=P-E, and can be easily calculated by a computer or the like from the torque of the servo motor 9 obtained by the torque detection means 13.

In the heating process, sufficient fusion is achieved when the foaming pressure reaches a certain value, for example, 1.2 to 2.0 kg/
If the heating step is completed at a foaming pressure of about cffl, appropriate heating can be performed in the minimum necessary time.

In addition, the molded product is removed by opening the mold when the foaming pressure drops to a set value.
If the foaming pressure F drops to about 0.4 to 0.05 kg/c4, it can be taken out without deformation.

The foaming pressure detection method and device for a foaming molding machine according to the present invention have the above-described configuration, and the mold closing of the foaming mold 2 by the servo motor 9 can be performed by force to the minimum necessary level. This can contribute to energy savings.

In addition, by detecting the torque generated by the servo motor 9, the foaming pressure in the molding space 15 of the foam molding mold 2 can be detected, and the heating process and cooling process are performed at an appropriate foaming pressure to form the mold. It is possible to take out the product at the appropriate time.Furthermore, the foaming pressure obtained here is
This is the entire foaming pressure within the molding space 15 of the foam molding die 2, and is highly reliable, making it possible to prevent deformation of the molded product.

Further, since it is not necessary to attach it to the foam molding mold 2, the foaming pressure can be controlled no matter what kind of mold is used.

〔Effect of the invention〕

The method and device for detecting foaming pressure in a foam molding machine according to the present invention are as described above, and the servo motor can close the mold for foam molding using force to the minimum necessary level. This can contribute to energy savings.

In addition, by detecting the torque generated by the servo motor, it is possible to detect the foaming pressure in the bottom space of the foam mold, allowing the completion of the heating process and the removal of the molded product at the appropriate time. It is possible.

Furthermore, the foaming pressure obtained here is the entire foaming pressure within the bottom space of the 4° mold for foam molding, and is highly reliable and can prevent deformation of the molded product. It is.

Furthermore, since there is no need to attach it to a mold for foam molding, the foaming pressure can be controlled no matter what kind of mold is used.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the main parts of the foam molding machine body used in the foaming pressure detection method and device for the foam molding machine according to the present invention, and FIG. 2 is a simplified block diagram for explaining the main parts of the foam molding machine. FIG. 3 is an explanatory sectional view of a foam molding die used in the present invention, and FIG. 4 is a flowchart of the present invention. 13: Torque detection means, 14: Torque monitor, 15:
Molding space, 16: Patsukin. Fixed formwork, fixed mold, moving mold, ball screw shaft, servo motor, position detection means, 2: 4: 6: 8: 10: 12: Foaming mold, moving formwork, moving means, pole nut, belt , servo control section,

Claims (1)

[Scope of Claims] 1) A fixed formwork fixed to the main body of the foam molding machine and to which one of the molds for foam molding is attached; A foam molding machine comprising: a movable formwork to which the other mold of the molds is attached; and a servo motor that moves the movable formwork opposite to the fixed formwork, the movable formwork attached to the movable formwork. A mold position detection means, a servo control unit to which a position signal detected by the position detection means is fed back and control the servo motor based on the feedback, and a torque detection means to convert the torque of the servo motor into voltage. and after the foam molding mold is closed, a micro gap is created between both molds, and the foaming pressure acting in the direction of increasing the distance between both molds during foam molding is detected by the position detection means. is fed back to the servo control unit, and the foam molding process is performed while controlling the servo motor to maintain the minute gap constant, and at the same time, the torque of the servo motor is converted into voltage by the torque detection means. A method for detecting foaming pressure in a foam molding machine. 2) A fixed formwork that is fixed to the foam molding machine main body and to which one of the foam molding molds is attached; A foam molding machine comprising: a movable formwork to which a mold is attached; and a servo motor that moves the movable formwork opposite to the fixed formwork; a servo control unit that controls the servo motor based on the feedback of a position signal detected by the position detection unit; and a torque detection unit that converts the torque of the servo motor into voltage. Foaming pressure detection device in molding machine.