JPH0366139B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is capable of heating each region in the axial direction of the cylinder to a temperature and condition suitable for the purpose while the plastic forming raw material is passed through the cylinder. The present invention relates to a molding apparatus configured as follows.

[Conventional technology]

Generally, plastic molding is carried out by utilizing the plasticity of the synthetic resin that is the main raw material. There are various processing methods depending on the properties of the resin and auxiliary materials, but most of them are molding methods that utilize the heat-resistant properties of the resin, that is, thermoplasticity or thermosetting.

Such molding methods include compression molding, transfer molding, injection molding, extrusion molding, blow molding, calendering, and the like.

Among these, thermoplastic molding material is supplied into the cylinder from a supply device, sent to the heating section by a screw or plunger, and the molding material, which has become plastic after being heated and pressurized in the heating section, is transferred to the cylinder. Molding apparatuses for molding extrudates by extruding from a nozzle or die provided at the tip of the mold or by using a press mold are well known and widely used for molding thermoplastic materials. .

In the above-mentioned molding equipment, the molding material is heated and compressed to a predetermined temperature and pressure determined mainly by the type of synthetic resin that is the raw material of the molding material at each part in the axial direction of the cylinder to fluidize it. It is necessary to
If this temperature and pressure are not maintained at predetermined values at each of the above axial locations, the mold will not be filled by mixing, melting, and extrusion at each axial location within the cylinder. If the product is not perfect, pores, cracks, distortions, etc. may occur in the product, resulting in incomplete processing.

However, this predetermined temperature depends on the shape of the product,
The temperature of the molding material changes depending on the temperature of the mold, the pressure inside the cylinder, etc. Also, since the molding material is heated by the shear heat generated as the screw rotates, the temperature of the molding material also changes due to changes in the torque applied to the screw. temperature fluctuates.

Therefore, during each molding process, the temperature must be controlled to suit the molding conditions.

Therefore, in order to be able to heat each axial portion of the cylinder to a temperature suitable for each purpose, a heating induction tube is constructed by joining a plurality of short heating tubes in the axial direction. A plastic melting device for inductively heating this heating tube is disclosed in Japanese Patent Publication No. 1983-6617. The interior of the heating guide tube disclosed herein forms a guide path having a medium diameter mixing section, an enlarged diameter melting section, and a supply section whose diameter decreases toward the tip.

The wall of the heating induction tube is composed of an inner layer made of a material having a large hysteresis effect (for example, iron) and a heating layer provided to cover the entire surface of the inner layer. The heating layer consists of a silicon anti-corrosion layer painted on the outer peripheral surface of the inner layer, and a magnetic induction layer made of, for example, an aluminum coil provided on the outside of this anti-corrosion layer, supporting the magnetic induction layer from the outside. For example, a heat-resistant adhesive tape layer is wound using a heat-resistant adhesive tape made of heat-resistant glass tape coated with an adhesive, and the outside of the heat-resistant adhesive tape layer is coated with meat. A heating layer is constructed by providing a thick heat-retaining layer made of heat-resistant asbestos, and covering the outer peripheral surface of the heat-retaining layer with a non-excitation layer made of, for example, an aluminum plate.

[Problem to be solved by the invention]

In this way, a plurality of short heating tubes each having a heating layer on the outside and a ferrous inner layer with different inner diameters in the mixing section, melting section, and supply section are joined together in the axial direction to form an integrated length. It is technically difficult to construct a slat-shaped heating induction tube for pressure-resistant bonding, and the thermoplastic molding raw material that has accumulated in the bonded area and deteriorated may peel off and get mixed in, causing molding problems. There was a defect that made the product defective.

The present invention does not have such drawbacks, and furthermore, it has a flexible cylinder that expands or contracts uniformly with temperature changes, and each part of the cylinder in the axial direction can be adjusted to a temperature or temperature that suits the purpose. The object of the present invention is to provide a molding device that can be heated and maintained in a certain state.

[Means to solve the problem]

The molding device of the present invention has a substantially uniform inner diameter in the axial direction, a desired axial length, and has a mounting member such as a flange at the rear end and a joining member for joining a die etc. at the tip. A thin-walled steel tube, a heat-resistant, high-tensile, non-magnetically-permeable wire that increases pressure resistance by wrapping the thin-walled steel tube, a heat-resistant heat insulating material such as foamed ceramics that covers the wire, and a portion of the thin-walled steel tube, respectively. a plurality of inductors distributed in the axial direction of a thin-walled steel pipe for induction heating; a power supply device that supplies alternating current or pulsed current to the inductors;
A plurality of temperature detectors are installed to detect the temperature of each part distributed in the axial direction of the thin-walled steel pipe to detect the temperature when the thin-walled steel pipe is induction-heated, and a signal from each temperature detector is used to detect the temperature. The temperature sensor includes a control device for the power supply device that controls the power, frequency, or number of pulses of the alternating current or pulse current that the power supply device supplies to the inductor corresponding to the temperature detector.

[Effect]

The thin-walled steel pipe housing the screw is heated by induction heating using a plurality of inductors distributed in the axial direction to partially heat the thin-walled steel pipe, so it can be heated quickly. The heating temperature is determined by controlling the power, frequency, or number of pulses supplied from the power supply to the corresponding inductor by a control device that receives signals from temperature detectors distributed in the axial direction. Since the temperature of the steel pipe is controlled, it has become extremely easy to control the temperature of each part of the thin-walled steel pipe. Since the object being heated is a cylindrical thin-walled steel tube with a uniform cross-sectional shape, the expansion and contraction associated with the temperature changes that rise and fall under temperature control are performed in the axial direction of the thin-walled steel tube. This eliminates the problem of cylinders with complicated cross sections that displace irregularly and cause the screw to be offset. Furthermore, the thin-walled steel tube is wrapped with heat-resistant, high-tensile, non-magnetic wire to increase its pressure resistance, resulting in a structure that can withstand the high temperatures and pressures used when kneading molding materials. It's getting old. Moreover, since it is made of wire wrapped tightly, there is flexibility in the direction in which the thin-walled steel pipe can be bent. Therefore, the tip of the long cantilevered screw may drop due to natural deflection, error or wear of the support device, or may be displaced due to heating, causing the kneading pressure of the molding material to increase.
Even if the kneading pressure becomes uneven around the screw, it flexibly responds to this and works to keep the kneading pressure uniform around the screw. On the other hand, since the wire that wraps around the thin-walled steel tube is non-magnetic, the wire itself is not heated by induction, increasing the pressure resistance of the thin-walled steel tube and adapting to the displacement and deformation of the thin-walled steel tube. .

〔Example〕

Hereinafter, the details of the present invention will be explained based on the drawings.

FIG. 1 is an explanatory diagram showing one embodiment of the molding device according to the present invention, FIG. 2 is a partially enlarged sectional view showing the configuration of the cylinder, and FIG. 3 is an explanatory diagram showing another embodiment. .

FIG. 1 shows an extrusion molding device,
In Figures 1 and 2, 1 is a cylinder, 1-1 is a thin-walled steel pipe, 1-2 is a high-tensile wire, 1-3 is a heat-resistant heat insulating material such as foamed ceramics, 2 is a screw, 3
is a flange, 4 is a reduction gear, 5 is a motor, 6 is a supply device, 7 is a supply device mounting member, 8 is a support column, 9 is a die, 10 is a die joining member, 11 is a breaker plate, 12 is a wire mesh, 13, 13 1 is an inductor (excitation coil for high-frequency induction heating); 14 and 14 are heat-sensitive detectors such as thermocouples and thermistors; 15 is a power supply device for the motor 5; 16 is a power supply device for the inductors 13 and 13;
7 is an A/D converter, and 18 is a control device.

As shown in FIG. 2, the cylinder 1 is, for example,
Made of SKD-4 material, wall thickness approximately 2.8mm, inner diameter approximately 35mm.
A heat-resistant non-magnetic permeable high tensile strength wire material 1-2 made of carbon fiber, silicon carbide, etc. is wrapped around the outer periphery of a thin steel pipe 1-1 formed to a diameter of φ, and is sufficiently tightened. Formed by coating with.

Therefore, the thin-walled steel pipe 1-1 of the cylinder 1 has a thin, ring-shaped, uniform cross-sectional shape, has a low heat capacity, expands and contracts in the axial direction due to temperature changes, and does not bend, and has sufficient heat resistance. have sex. The rear end of the thin-walled steel pipe 1-1 has a mounting member 3 such as a flange, through which it is supported by a reduction gear 4, and its tip is supported by a support 8, and a die is attached to the tip. A joining member 10 is attached to join the parts.

The screw 2 is rotatably provided coaxially within the thin-walled steel pipe 1-1 of the cylinder 1, and its rear end is cantilevered by a reduction gear 4 that decelerates the rotation of the motor 5 and increases the torque. 5, the molding material supplied from the supply device 6 into the thin-walled steel pipe 1-1 of the cylinder 1 is sent to the heating section, and at the same time the molding material is heated by the shear heat generated by the rotation of the screw 2. The molding material, which has been heated and pressurized in the heating section and has become plastic, is extruded from the die 9.

In other words, in a cylinder made of a thin-walled steel pipe, the intermediate region in the longitudinal direction of the cylinder is the heating and pressurizing part that melts the molding material, whereas the front supply device side is
This is the region where mixing is performed while heating at a relatively low temperature, and the tip side part is configured so that the flow cross-sectional area of the molten material is almost uniform in the axial direction, so that the metering of the extruded molten material is made easier. It is meant to be done.

The operation of the power supply device 15 that supplies electric power to the motor 5 is controlled by a control device 18, and the starting, stopping, and rotation speed of the motor 5 are controlled.

A breaker plate 11 having a large number of holes and a wire mesh 12 held by the breaker plate 11 are provided between the tip of the thin-walled steel pipe 1-1 of the cylinder 1 and the die joining member 10, thereby controlling the flow of the molding material. The materials are thoroughly kneaded to make the heating uniform, and at the same time, pressure is applied to the thin-walled steel pipe 1-1 of the cylinder 1.

The supply device 6 is attached to a supply device attachment member 7 fixed to the flange 3, and supplies molding material into the thin-walled steel pipe 1-1 of the cylinder 1.

The inductors 13, 13 are the thin-walled steel pipe 1- of the cylinder 1.
A plurality of them are provided at appropriate intervals distributed in the axial direction of the cylinder 1, and AC or pulse current is supplied from the power supply device 16 to heat the thin-walled steel pipe 1-1 of the cylinder 1 by induction heating.

Generally, a coil called an inductor is wound around a cylindrical conductor, and when an alternating current is passed through the inductor, an eddy current is generated in the conductor due to electromagnetic induction, and the conductor generates heat due to the eddy current loss generated at this time. do.

In this case, since the alternating current has a skin effect, the eddy current concentrates on the surface of the conductor and decreases exponentially toward the center. Since the depth of penetration of this eddy current is inversely proportional to the square of the frequency of the alternating current supplied to the inductor, the depth of penetration can be freely changed by appropriately setting this frequency.

The part of the cylinder 1 where the inductors 13, 13 are provided constitutes a heating section of the thin-walled steel tube 1-1, and the molding material is heated by this heating section through heat conduction from the inner circumferential surface of the thin-walled steel tube 1-1. heated by.

In this case, the AC power (normal current value) supplied to the inductor 13 provided at the rear of the thin-walled steel pipe 1-1, that is, the part close to the replenisher 6, is lowered, and as it approaches the front, the The part of the thin-walled steel pipe 1-1 connected to the replenisher 6 with a high temperature is set to room temperature, the temperature of the thin-walled steel pipe 1-1 of the part close to this is set to a relatively low temperature, and the temperature is gradually increased to cool the tip of the thin-walled steel pipe 1-1. So, 160
The desired temperature is maintained at approximately 300°C to 300°C.

A plurality of heat-sensitive detectors 14, 14 are provided at key points on the outer periphery of the cylinder 1, that is, at portions corresponding to the mixing section, pressurization/compression section, measuring section, etc. of the screw 2, respectively, and the heat-sensitive detectors 14, 14 are installed at key points on the outer periphery of the cylinder 1, that is, at portions corresponding to the mixing section, pressurization/compression section, measuring section, etc. of the screw 2, respectively. Detects the temperature of each part in each direction.

The temperature of each part of the thin-walled steel pipe 1-1 detected by the heat-sensitive detectors 14, 14 is converted into a digital signal by the A/D converter 17 and sent to the control device 18. Based on this signal, the control device 18 determines the AC power, frequency, or number of pulses sent from the power supply device 16 to the corresponding inductors 13, 13, and the motor 5.
1. Controls the operation of a power supply device 15 that supplies power to the

The die joint part 10 is attached to the tip of the thin-walled steel tube 1-1, and has a funnel-shaped flow path that guides the material extruded from the thin-walled steel tube 1-1 to the die 9.

The die 9 is attached to the die joint 10, from which the fluidized molding material is extruded and molded into a desired shape.

When granular or granular molding material is supplied from the supply device 6 into the thin-walled steel pipe 1-1, the screw 2 is rotated by the drive of the motor 5, and the molding material is supplied to the thin-walled steel pipe 1-1 of the cylinder 1. The mixture is mixed while being heated to a relatively low predetermined temperature in the axially front part, and then sent to the pressurizing/heating part in the front intermediate region.

An alternating current or pulse current is supplied from the power supply device 16 to the inductors 13, 13 provided in the heating section of the thin-walled steel pipe 1-1 of the cylinder 1, and an eddy current is generated in the thin-walled steel pipe 1-1, and this is caused by induction heating. generates heat.

The heat generated by this induction heating is 2 to 3 times more efficient in terms of power than heating by power lines, etc., and is also cheaper and more durable.Furthermore, the thin-walled steel pipe 1-1 of the cylinder 1 is heated by applying heat from the outside. Since the thin-walled steel pipe 1-1 itself is heated by directly generating heat, the heat capacity of the heating means is not related to temperature control, so the temperature can be adjusted immediately in response to commands from the control device 18. I can do it.

At this time, the temperature of each part of the thin-walled steel pipe 1-1 of the cylinder 1 detected by the heat-sensitive detectors 14, 14 is converted into a digital signal by the A/D converter 17 and sent to the control device 18, Based on this signal, the control device 18 determines the alternating current power or frequency sent from the power supply device 16 to the corresponding inductors 13, or the power or pulse number of the pulse current, and the control device 18 when the power is supplied to the motor 5. Control operation.

Therefore, the molding material is the thin-walled steel pipe 1- of the cylinder 1.
It is heated and pressurized by heat conduction from the inner wall surface of screw 1, rotation of screw 2, and the accompanying shear heat, and is maintained at a temperature and pressure suitable for extrusion, and becomes a fluid.

The fluidized molding material is extruded from the die 9 at a constant speed through the die joint 10 and molded into a desired shape.

Figure 3 shows an injection molding device, and the third
In the figure, 19 is a cylinder, 20 is a motor housing, 21 is a screw, 22 is a check valve, 23
is the motor, 24 is the piston, 25 is the rod, 26
is a hydraulic cylinder, 27 is a replenisher, 28 is a replenisher mounting member, 29 is a flange, 30 and 30 are inductors,
31, 31 is a heat sensitive detector, 32 is a nozzle, 33 is a nozzle mounting member, 34 is a power supply device for the motor 23,
35 is an inductor power supply device, 36 is an A/D converter,
37 is a control device.

The cylinder 19 is formed by wrapping a heat-resistant high-tensile wire material such as carbon fiber or silicon carbide around the outer periphery of a thin steel pipe, tightening it sufficiently, and covering it with foamed ceramics or the like, as in the previous embodiment.

The screw 21 is cantilevered in the cylinder 19 so as to be rotatable and slidable in the axial direction, and is rotated by the drive of the motor 23 to mix the molding material supplied from the replenisher 27. At the same time as it is sent to the pressurizing/heating section, the molding material is heated by the shear heat generated at that time, moves as the piston 24 moves, and is heated and pressurized in the heating section to send the plasticized molding material to the nozzle. 32.

A backflow prevention valve 22 is provided at the tip of the screw 21 to prevent the material from flowing back when the molding material is injected from the nozzle 32.

The motor 23 is housed in the motor housing 20 and is attached to one end of a rod 25 connected to the piston 24. The motor 23 moves in the axial direction in conjunction with the piston 24, and its drive shaft is connected to the rear end of the screw 21. It is connected and the screw 21 is rotated.

Piston 24 slides within a hydraulic cylinder 26 attached to the rear end of motor housing 20 and causes motor 23 to move axially via rod 25.

The replenisher 27 is attached to a replenisher mounting member 28 fixed to the flange 29 and supplies molding material into the thin-walled steel pipe of the cylinder 19.

A plurality of inductors 30, 30 are provided at appropriate intervals along the outer circumference and axial direction of the cylinder 19, and AC current is supplied from the power supply device 35 to heat the thin-walled steel pipe inside the cylinder 19 by induction heating.

The portion of the cylinder 19 where the inductors 30, 30 are provided constitutes a heating section, and the molding material is heated in this heating section by heat conduction from the inner peripheral surface of the thin-walled steel pipe of the cylinder 19.

The heat-sensitive detectors 31, 31 are distributed in the axial direction of the thin-walled steel tube of the cylinder 19, and a plurality of them are provided at key points thereof, that is, at parts corresponding to the mixing section, pressurization/compression section, measuring section, etc. of the screw 21, respectively. , the temperature of each part of the thin-walled steel pipe of the cylinder 19 is detected.

The temperature of each part of the thin-walled steel pipe of the cylinder 19 is detected by the heat-sensitive detectors 31, 31, and is converted into a digital signal by the A/D converter 36, and then sent to the control device 37.
sent to. Based on this signal, the control device 37 determines the AC power or frequency sent from the power supply device 35 to each corresponding inductor 30, or the power or number of pulses of the pulse current, and the power supply device 34 that supplies power to the motor 23. Control operation.

The nozzle 32 is attached to a nozzle attachment member 33 attached to the tip of the thin-walled steel tube of the cylinder 19, and is connected to a mold (not shown), from which the fluidized molding material is injected into the cavity of the mold. be done.

However, at the beginning of each cycle, Screw 2
1 is at a retreated position (the position shown in the figure) within the thin-walled steel pipe of the cylinder 19, and when granular or powdered molding material is supplied from the supply device 27 into the thin-walled steel pipe of the cylinder 19, it is driven by the motor 23. Then, the screw 21 rotates, and the molding material is mixed while being heated to a relatively low predetermined temperature in the axially front portion of the thin-walled steel pipe of the cylinder 19, and is sent to the pressurizing and heating section in the front intermediate region.

Inductor 3 provided in the heating part of cylinder 19
0 and 30 are supplied with alternating current or pulsed power from a power supply 35 to generate an eddy current in the thin-walled steel tube of the cylinder 19, causing it to generate heat by induction heating.

At this time, the temperature of each part of the thin-walled steel pipe of the cylinder 19 detected by the heat-sensitive detectors 31 and 3 is A/
It is converted into a digital signal by the D converter 36 and sent to the control device 37, and based on this signal, the control device 3
7 from the power supply 35 to each corresponding inductor 30,3
0 and the alternating current power or frequency sent to motor 2
3. Controls the operation of a power supply device 34 that supplies power to 3.

Therefore, the molding material is heated and pressurized by heat conduction from the inner wall surface of the thin-walled steel pipe of the cylinder 19, the rotation of the screw 21, and the accompanying shear heat, and is given a temperature and pressure suitable for injection, and flows. Become a body,
It is sent to a space formed by the tip of the thin-walled steel pipe of the cylinder 19 and the inner wall of the nozzle mounting member 33.

Next, the screw 21 moves in the direction of the nozzle 32 as the piston 24 moves, and the molding material sent to the cavity is injected from the spout of the nozzle 32 into the cavity of the mold (not shown) to form the desired shape. is formed into.

For temperature control, for example, when forced cooling is used, a pipe through which a cooling liquid flows between each inductor 13 or 30 is wound around the cylinder 1 or 19, and cooling of each pipe is performed. Stopping the flow of liquid,
Appropriate means, such as switching and controlling the flow rate or the temperature of the coolant using a signal from the heat-sensitive detector 14 or 31, can be taken.

Note that the configuration of the present invention is not limited to the above-mentioned embodiments; for example, in the embodiment, an inductor with no iron core is provided around the cylinder; An inductor with a ferrous core wrapped around the cylinder may be used. In this case, a plurality of ferrous core inductors are provided along the cross section perpendicular to the axis of the cylinder, and these are set as a set, and the inductors are arranged at appropriate intervals. The configuration is such that a plurality of sets are provided separated by.

〔Effect of the invention〕

The thin-walled steel pipe housing the screw is heated by induction heating using a plurality of inductors distributed in the axial direction to partially heat the thin-walled steel pipe, so it can be heated quickly. The heating temperature is partially controlled by a control device that receives signals from temperature detectors distributed in the axial direction and controls the power, frequency, or number of pulses supplied from the power supply device to the corresponding inductor. Since the temperature of the thin-walled steel pipe can be controlled, it has become possible to control the temperature of each part of the thin-walled steel pipe extremely easily. Since the object being heated is a cylindrical thin-walled steel tube with an even cross-sectional shape, the expansion and contraction associated with the temperature changes that occur up and down due to temperature control occur in the axial direction of the thin-walled steel tube. The screws no longer shift irregularly and cause the screws to shift to one side. Furthermore, the thin-walled steel tube is wrapped with a heat-resistant, high-tensile, non-magnetic wire rod to increase its pressure resistance, resulting in a structure that can withstand the high temperatures and pressures used when kneading molding materials. ing. Furthermore, since the thin-walled steel pipe is wound tightly with wire rods, there is flexibility in the direction in which the thin-walled steel pipe is bent.

Therefore, due to natural deflection of the long cantilevered screw, errors or wear of the support device, the tip of the screw may drop, or it may be displaced due to heating, resulting in uneven kneading pressure of the molding material around the screw. It has the effect of keeping the kneading pressure uniform around the screw by responding flexibly even if the screw becomes wet. On the other hand, since the wire that wraps around the thin-walled steel tube is non-magnetic, the wire itself is not heated by induction, and it adapts to the displacement and deformation of the thin-walled steel tube while increasing its pressure resistance.

This allows the temperature of the molding material to be adjusted appropriately, keeping the molding material at the desired temperature and pressure at all times.
It can reduce pores, cracks, distortion, etc. of products, improve molding accuracy, and shorten molding time.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the molding device according to the present invention, FIG. 2 is a partially enlarged sectional view showing the configuration of the cylinder, and FIG. 3 is an explanatory diagram showing another embodiment. . 1,19...Cylinder, 1-1...Steel pipe, 1-
2...High tensile wire rod, 1-3...Ceramic foam,
2, 21... Screw, 5, 23... Motor,
6,27...Supplier, 9...Die, 13,13,
30, 30...inductor, 14, 14, 31, 31
...Thermal detector, 15...Power supply device for motor 5,
16...Power supply device for inductors 13, 13, 18,3
7... Control device, 24... Piston, 32... Nozzle, 34... Power supply device for motor 23, 35...
Power supply device for the inductors 30, 30.

Claims (1)

[Claims] 1. Thermoplastic molding material is supplied into the cylinder from a supply device, and sent to the heating and pressurizing section of the cylinder by a screw or plunger provided coaxially within the cylinder, and is also heated at the heating section. In a molding device that extrudes a molding material that has become plastic through heating and pressurization through a nozzle or die provided at the tip of the cylinder, it is possible to mold the molding material to a desired axial length with a substantially uniform inner diameter in the axial direction. a thin-walled steel pipe having a rear end portion for attaching a flange or the like and a distal end portion for joining a die or the like;
A non-magnetically permeable wire rod with heat-resistant high tension that increases pressure resistance by wrapping this thin-walled steel pipe, and a heat-resistant heat insulating material such as foamed ceramics that covers the wire rod.
A plurality of inductors distributed in the axial direction of the thin-walled steel tube for partially inductively heating the thin-walled steel tube, a power supply device that supplies alternating current or pulsed current to the inductors, A plurality of temperature detectors are distributed in the axial direction of the thin-walled steel pipe to detect the temperature during induction heating, and the temperature is detected based on the signal from each temperature detector. and a control device for the power supply device that controls the power, frequency, or number of pulses of the alternating current or pulse current that the power supply device supplies to the inductor corresponding to the molding device.