JPH0530367B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in synthetic resin molding equipment.

[Conventional technology]

Generally, plastic molding is carried out by utilizing the thermoplasticity 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, etc.
Most of the molding methods utilize the heat-resistant properties of synthetic resins, that is, thermoplasticity or thermosetting.

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

Among these, thermoplastic molding material is supplied into the cylinder from a supply device, sent to the heating section by a screw provided so as to be rotatable and slidable in the axial direction, and heated and processed in the heating section. There is a known molding device that injects the compressed molding material into a plastic shape into the cavity of a mold from a nozzle provided at the tip of the cylinder. It is also used as a molding material.

The present inventor disclosed a new synthetic resin molding apparatus in Japanese Patent Application No. 59-018488. That is, thermoplastic molding material is supplied into the cylinder from a supply device, and sent to the heating section of the cylinder by a rotatably supported screw, and the molding material is heated and pressurized to become plastic. A screw-type extrusion device extrudes from a nozzle provided at the tip of the cylinder, and a plasticized molding material is received into the cylinder tube from the nozzle of the screw-type extrusion device, and a predetermined amount of this is sent from a nozzle provided at the cylinder head. It consists of an injection cylinder device that precisely injects the plastic, an upper mold and a lower mold equipped with a heating section and a cooling section as necessary, and a device that brings the upper and lower molds into contact with each other. an injection mold device for molding the shaped molding material in a cavity formed between the upper and lower molds; and the screw type extrusion device, injection cylinder device, and injection mold according to a predetermined program. This is a synthetic resin molding device that includes a control device that controls the operation of the device.

Therefore, when using the above-mentioned synthetic resin molding apparatus, it is possible to precisely control the amount of plastic to be injected, and also to automate each driving device and heating device, so that the device can be operated at the most favorable timing. Therefore, it has become possible to mold large, complex-shaped molded products in the best possible condition.

However, in the above synthetic resin molding device,
There has been a problem in that it is difficult to maintain the molding material at a predetermined temperature determined by the type of synthetic resin that is the raw material for the molding material.

In the synthetic resin molding process, it is necessary to heat and compress the molding material to a predetermined temperature and pressure determined mainly by the type of synthetic resin that is the raw material for the molding material, and to fluidize it. If this value is not maintained, the filling of the mold may become incomplete, or the product may develop pores, cracks, or distortion, and complete processing may not be possible. Moreover, the desired temperature of the resin extruded into the nozzle or die varies depending on the shape of the product, the type of mold, the pressure inside the cylinder, the extrusion cycle, and the amount of extrusion per product. Extrusion is generally intermittent, whereas heating is continuous. In addition, the molding material is heated not only by the heating parts installed in each part, but also by the shear heat generated as the screw rotates, so changes in the driving energy applied to the screw also affect the temperature of the molding material. fluctuates, but
This driving energy depends on the pressure and temperature of the resin within the cylinder.

Furthermore, in the conventional apparatus, a heater is provided inside the cylinder or along the outer circumferential surface, and the cylinder is heated by this heater, and thereby the molding material is heated. The heat capacity is large, and the heat capacity of the heater itself and the coating material of the heater are related to temperature control, so it is difficult to accurately raise or lower the temperature of the cylinder to a desired value, and furthermore, the temperature inside the cylinder Another problem was that since the resin moved intermittently, it was difficult to maintain the molding material extruded from the cylinder at a constant temperature suitable for processing.

[Problems to be solved by the present invention]

The present invention has been made based on the above-mentioned viewpoints, and its purpose is to configure a molding material so that it can be heated more rationally, thereby controlling the temperature and pressure of the molding material. If done properly, the resin extruded from the equipment will always be kept at the optimal temperature and pressure for processing, reducing pores, cracks, and distortion in the product, increasing molding precision, and significantly shortening molding time. An object of the present invention is to provide a resin molding device.

[Means for solving problems]

In order to achieve the above object, the synthetic resin molding apparatus disclosed by the present inventor includes a device for detecting the temperature of the molding material that has become plastic, and an output of the temperature detecting device. This is achieved by a synthetic resin molding apparatus equipped with a device for controlling the position and/or rotation speed of the screw so as to maintain the desired value.

[Effect]

By configuring as described above, the energy given to the resin in each part of the cylinder is reduced over time.
The temperature and pressure of the resin extruded from the cylinder are always maintained at the optimum conditions for processing by appropriately controlling the spatial movement speed of the resin, thereby preventing pores, cracks, or distortion of the product. This improves molding accuracy and significantly shortens molding time.

〔Example〕

Hereinafter, details of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing one embodiment of the synthetic resin molding device according to the present invention, FIG. 2 is an explanatory diagram showing another embodiment of the screw type extrusion device, and FIG.
It is a sectional view taken along the line AA in FIG. 2.

First, the explanation will be given with reference to FIG.

In Figure 1, 1 includes a synthetic resin molding device, 2 a screw type extrusion device, 3 an injection cylinder device, 4 an injection mold device, and 5 a numerical control device that collectively controls each of the above devices. It is a control device.

The screw type extrusion device 2 includes a cylinder 6, a screw 7, a breaker plate 8, a wire mesh 9, an inductor (excitation coil for high frequency induction heating) 10, 10,
Resin temperature detection device 11, 11, check valve 1
2, material supply device 13, compactor 14, motor 1
5, an encoder 16, a motor 17 that rotates the screw 7, an encoder 18 that detects the position and/or rotational speed of the motor 17, and an inverter 1;
9 and a converter 20 that converts the temperature detected by the resin temperature detection devices 11, 11 into an electrical signal.

In the case of this embodiment, the injection cylinder device 3 is configured to be able to accurately inject a predetermined amount by receiving a predetermined unit injection amount of molding material for each injection. ,
Cylinder heads 22, 23, pistons 25, 2
6. A cylinder 2 consisting of a piston rod 27, automatic valves 28, 29, a nozzle 30, an inductor (excitation coil for high-frequency induction heating) 31, and an inverter 32, which receives, fills, and injects molding material.
1. The internal volume space formed by the cylinder head 22 and the piston 25 is manufactured to a precise predetermined amount.

The injection mold device 4 includes a table 33, guide shafts 34, 34, a fixed plate 35, and nuts 36, 3.
6, mounting plate 37, heat insulating plate 38, receiving plate 39, spacer block 40, bush 41, mold valve 42,
Lower mold 43, upper mold 45, dielectric (excitation coil for high frequency induction heating) 44, 44 and 46, 46, guide receiving plates 47, 47, upper mold mounting plate 48, feed screw 4
9, a motor 50, a motor bracket 51, a slider 52, a slider receiving plate 53, a slider guide plate 54, an encoder 55, and an inverter 56.

Therefore, the motor 17 of the screw type extrusion device 2
The rear end of the screw 7 is connected to the shaft 17a, and the screw 17 rotates as the motor 17 rotates.At this time, the position and/or rotational speed of the screw 17 is controlled by an encoder 18.
detected by.

The screw 7 is rotatably installed in the cylinder 6, and feeds the plastic pellets, which are the molding material supplied from the replenisher 13, to the heating section, and at the same time heats the molding material by the shear heat generated at that time. The molding material, which has been heated and pressurized to become plastic, is extruded from the cylinder 6 through the check valve 12 into the cylinder 21 for quantitative injection of the injection cylinder device 3.

A breaker plate 8 having a large number of holes and a wire mesh 9 held by the breaker plate 8 are provided at the tip of the cylinder 6, which makes the flow of the molding material uniform, kneads the molding material well, and heats it. It equalizes.

The material supply device 13 is attached to the upper part of the cylinder 6, and compresses and supplies plastic pellets, which are molding materials, into the cylinder 6 in a sealed state using a compactor 14 and a motor 15. The rotation speed of the motor 15 is controlled by an encoder 16. detected by.

Inductor (excitation coil for high frequency induction heating) 10,
A plurality of screws 10 are provided in the cylinder 6 to surround the screw 7, and the cylinder 6 is heated by being supplied with electric power from the illustrated power supply device via an inverter 19. The portion of the cylinder 6 where the inductors 10, 10 are provided constitutes a heating section, and the molding material is heated in this heating section from the inner circumferential surface of the cylinder 6 by heat conduction.

In general, induction heating involves winding a coil called an inductor around a cylindrical conductor, and when an alternating current is passed through the inductor, an eddy current is generated within the conductor due to electromagnetic induction. Heat is generated due to loss. 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. The depth of penetration of this eddy current is inversely proportional to the square of the frequency of the alternating current supplied to the dielectric, so by setting this frequency appropriately, the depth of penetration can be freely changed, and the material Can be heated efficiently.

Further, the temperature of the molding material in the cylinder 6 heated by the inductors 10, 10 is detected by resin temperature detection devices 11, 11, and the detected value is converted into an electrical signal by a converter 20. After that, it is input to the control device 5.

When the molding material is supplied from the material supply device 13 into the cylinder 6 and the screw 7 is rotated by the drive of the motor 17, the molding material is delivered to the heating section of the cylinder 6, where it is heated. ,
A breaker plate 8 and a wire mesh 9 are pressurized and fluidized, and are further provided at the tip of the cylinder 6.
is then injected into the metered injection cylinder 21 via the check valve 12.

In the injection cylinder device 3, pistons 25 and 26 are slidably provided in a cylinder 21, and pistons 25 and 26 are installed in series at the center and openings at both ends of the cylinder 21 via cylinder heads 23, 22, and 24, respectively. There is. The piston rod 27 is slidably fitted into a hole 23a formed in the cylinder head 23, and a piston 25 is attached to one end of the cylinder rod 27, and a piston 26 is attached to the other end. Furthermore, a nozzle 30 is attached to the cylinder head 22.

Thus, the cylinder 21 is powered by an inductor 31 provided on its outer periphery via an inverter 32 from a power supply device (not shown).
1 is heated, and the pistons 25 and 26 fixed to the piston rod 27 are heated by hydraulic pressure being supplied from a hydraulic unit (not shown) to the cylinder 21 and automatic valves 28 and 29 provided on the outer periphery. Slide inside in the left and right directions in the figure.

The operation of the injection cylinder device 3 is such that at the beginning of each cycle, the pistons 25 and 26 are in the cylinder 2 position.
Hydraulic pressure is supplied to automatic valves 28 and 29 from a hydraulic unit (not shown) in synchronization with the injection of molten molding material into cylinder 21 via check valve 12. The molding material is injected until the piston 26 accurately moves to a predetermined position such as the end of the leftward movement in the drawing together with the piston 25 via the piston rod 27, and the amount of injected molding material is always maintained at a predetermined constant level. It's becoming more and more.

Next, when hydraulic pressure is supplied to the automatic valves 28 and 29 from a hydraulic unit (not shown), the piston 2
5 and 26 move to the right in the figure to the end of their movement, and accurately inject a predetermined amount of molding material into the cavity of the injection mold device 4.

The lower mold 43 of the injection mold device 4 has dielectrics 44, 44 inside, and is fixed on the table 33 via a mounting plate 37, a heat insulating plate 38, a receiving plate 39, a spacer block 40 and a bush 41. has been done.

Also, the sprue and runner through which the molten molding material passes from the nozzle 30 are connected to the receiving plate 39 and the bushing 41.
It is provided so as to communicate with the inside of the cavity of the lower mold 43 via a mold valve 42 provided therein.

The inductors 44, 44 and 46, 46 are connected to the lower mold 43.
The lower mold 43 and the upper mold 45 are heated by being supplied with electric power from a power supply device (not shown) provided inside the upper mold 45 through an inverter 56, and the molten molding material is distributed to various parts inside the mold cavity. After making sure that it is evenly distributed, the lower mold 43 and the upper mold 4
5 is cooled and molded.

The upper die 45 has four guide shafts 3 each erected on the table 33 so as to straddle the lower die 43.
A fixed plate 35 is attached to the upper ends of 4, 34 with nuts 36, 36, a feed screw 49 is screwed into a screw hole provided in the fixed plate 35, and a rotatable plate is attached to one end of the feed screw 49. The motor 50 is mounted so as to be movable up and down via an upper die mounting plate 48 which is fixed in the axial direction, and a feed screw 49 is attached to the shaft 50a of the motor 50, and the motor 50 is erected on the fixed plate 35. , a slider guide plate 54 having slits.
to the slider 52 via the motor bracket 51.
and is slidably attached to the slider receiving plate 53.

Furthermore, the upper mold 45 has four guide shafts as the feed screw 49 moves along the screw hole of the fixed plate 35 screwed into the feed screw 49 by rotation of the feed screw 49 driven by the motor 50. 34, 34 are guided to move up and down between predetermined positions, and a mold cavity for obtaining a desired molded product is formed at a position overlapping the lower mold 43.

When processing is performed by the synthetic resin molding apparatus 1 according to the present invention, when granular or powdered molding material is co-supplied from the material supply device 13 to the cylinder 6, the motor 17 is driven. The molding material is sent to the heating section of the cylinder 6, and the inductor 10, 10 provided in the heating section of the cylinder 6
An alternating current is supplied from a power supply device (not shown) via an inverter 19 to generate an eddy current in the cylinder 6, which generates heat by induction heating.

The temperature of the molding material in the cylinder 6 heated by the inductors 10, 10 is detected by the resin temperature detection devices 11, 11, and converted into an electric signal by the converter 20, and then the control device 5, the control device 5 calculates the total amount of heat held by the molding material in the cylinder 6, and compares this with the total amount of heat that the molding material should have under a predetermined ideal temperature distribution. If a deviation is found between the two, the motor 17 that drives the screw 7 is controlled so that the position and/or rotational speed of the screw 7 is controlled so that the deviation disappears. Control is carried out so that the temperature of the molding material in the cylinder 6 is maintained at an optimum temperature, and the synthetic resin molding process is carried out.

Next, FIGS. 2 and 3 will be explained.

In FIGS. 2 and 3, 2' is a screw type extrusion device, 57 is a cylinder whose inside is tapered, 58 is a screw, 58a is a shaft of the screw 58, 59 is a breaker plate, 60 61 is a wire mesh, 61 is a motor, 61a is a shaft of the motor 61, 62 is a gear attached to the shaft 61a of the motor 61, and 63 is a gear attached to the shaft 58a of the screw 58 and meshed with the gear 62. ,6
4 and 65 are the shaft 58 of the screw 58
66 is a motor support base, 66a and 66b are guide rod insertion holes formed in the motor support base 66, 66c is a rod fixing part, and 67, 67 are guide rods (however, in the drawing, Only one guide rod is depicted.
The other guide rod is omitted. ), 68
69 is a rod of the hydraulic cylinder 68, and 70 is a rail on which the motor support stand 66 is placed.

The illustrated screw type extrusion device 2' includes a heating device for heating the molding material, a temperature detection device for detecting the heating temperature of the molding material, an encoder for detecting the position and/or rotation speed of the screw 58, etc. has been omitted.

The motor 61 is placed on a motor support stand 66, and a gear 62 is attached to the shaft 61a of the motor 61. The gear 62 is a screw rotatably supported by bearings 64 and 65. It meshes with a gear 63 attached to the shaft 58a of 58.

The motor support stand 66 is placed on the rail 70,
The rod 69 of the hydraulic cylinder 68 is fixed to the rod fixing portion 66c, and the guide rods 67 and 69 are respectively fixed to the guide rod insertion holes 66a and 66b.
67 is inserted, and the supply of hydraulic pressure to the hydraulic cylinder 68 is switched by a hydraulic switching valve (not shown), thereby moving on the rail 70 in the left-right direction in the figure.

Then, a control device (not shown) calculates the total amount of heat held by the molding material in the cylinder 57, and compares this with the total amount of heat that the molding material should have under a predetermined ideal temperature distribution. , if a deviation is found between the two, the motor 6 drives the screw 58 so that the deviation disappears.
1, the motor support stand 66 is moved in the left-right direction by the hydraulic cylinder 68, and the position of the screw 58 within the cylinder 57 is controlled, so that the position between the screw 58 and the inner wall surface of the cylinder 57 is controlled. Processing is performed while controlling the frictional heat generated.

That is, if the screw 58 is moved to the left in the figure, the distance between the inner wall surface of the cylinder 57 and the screw 58 becomes wider, so the frictional heat generated between the two becomes lower. If the cylinder 57 is moved to the right, the distance between the inner wall surface of the cylinder 57 and the screw 58 becomes narrower, so that the frictional heat generated between the two becomes higher. Therefore, as mentioned above,
The rotation of the screw 58 is controlled by controlling the drive of the motor 61, and the motor support stand 66 is moved in the left and right direction by the hydraulic cylinder 68, thereby controlling the position of the screw 58 within the cylinder 57. By doing so, the temperature of the molding material can be controlled more appropriately.

〔Effect of the invention〕

Since the present invention is constructed as described above, according to the present invention, the energy given to the resin in each part of the cylinder of the screw type extrusion device is appropriately controlled over time and space according to the moving speed of the resin, and the cylinder Since the temperature and pressure of the extruded resin are always maintained at the optimum conditions for processing, pores, cracks, and distortions in the product are prevented, molding accuracy is increased, and molding time is significantly shortened. It is.

Note that the present invention is not limited to the embodiments described above. That is, for example, in this embodiment, the temperature of the molding material in the cylinder 6 is measured by the resin temperature detection device 1.
1 and 11, and based on the detected values, the control device 5 calculates the total amount of heat held by the molding material in the cylinder 6, and calculates the amount of heat held by the molding material in a predetermined ideal temperature distribution. If a deviation is found between the two, the motor 17 that drives the screw 7 is controlled so that the deviation disappears.
The position and/or rotation speed of the cylinder 6 is controlled so that the temperature of the molding material in the cylinder 6 is always maintained at an optimum level. It may be configured to adjust the alternating current. Further, although an inductor is used as the heating device, it is not limited to the above-mentioned inductor, and other known heating devices can be used. The style, structure, control method, etc. of other parts can be freely changed within the scope of the purpose of the present invention, and the present invention encompasses all of them.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the synthetic resin molding device according to the present invention, FIG. 2 is an explanatory diagram showing another embodiment of the screw type extrusion device, and FIG.
It is a sectional view taken along the line AA in FIG. 2. 1... Synthetic resin molding device, 2, 2'... Screw type extrusion device, 3... Injection cylinder device, 4...
...Injection mold device, 5...Control device, 6,5
7... Cylinder, 7, 58... Screw, 8...
... Breaker plate, 9 ... Wire mesh, 10 ... Dielectric, 11 ... Resin temperature detection device, 12 ... Check valve, 13 ... Material supply device, 14 ... Coupler, 15, 17 ... Motor, 16, 18... Encoder, 19... Inverter, 20... Converter, 21... Cylinder, 42... Type valve, 43
... lower mold, 45 ... upper mold, 66 ... motor support stand, 67 ... guide rod.

Claims (1)

[Scope of Claims] 1. Thermoplastic molding material is supplied into the cylinder from a supply device, and sent to the heating section of the cylinder by a rotatably supported screw, where it is heated and pressurized to become plastic. A screw-type extrusion device that extrudes the molded material from a nozzle provided at the tip of the cylinder; and a screw-type extrusion device that receives the plasticized molding material from the nozzle of the screw-type extrusion device into a cylinder tube, which is provided in the cylinder head. an injection cylinder device that injects a precisely controlled predetermined amount from a nozzle, at least two molds that are coupled to each other to form a desired cavity, and a device that brings these molds into contact with and separates them,
an injection mold device for receiving and forming plasticized molding material from the nozzle of the injection cylinder device into a cavity formed between the molds; and the screw type extrusion device according to a predetermined program; In a synthetic resin molding device comprising a control device for controlling the operation of an injection cylinder device and an injection mold device, a device for detecting the temperature of the molding material that has become plastic, and an output of the temperature detection device. The synthetic resin molding apparatus described above is further provided with a device for controlling the position and/or rotation speed of the screw so as to maintain the screw at a desired value.