JPH0729332B2 - Synthetic resin molding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a synthetic resin molding method.

[Conventional technology]

Generally, plastic molding is performed by utilizing the thermoplasticity or thermosetting property of a synthetic resin as a 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 utilizing the property of synthetic resin against heat, that is, thermoplasticity or thermosetting property.

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

Of these, a thermoplastic molding material is supplied from a replenisher into the cylinder, sent to a heating section by a screw provided rotatably and slidably in the axial direction, and heated and pressurized by the heating section. A molding method is known in which a plasticized molding material is injected into the cavity of a mold from a nozzle provided at the tip of the cylinder, and is also used for molding with a thermosetting material. Has been done.

Therefore, in any of the above-mentioned molding means, in order to evenly spread the molding material to every corner of the mold, it is necessary to set the molding pressure sufficiently high in any case. ,
In order to secure the pressure resistance against this, the molding apparatus itself had to be large-scaled.

[Problems to be Solved by the Present Invention]

The present invention has been made to solve the above problems, and an object thereof is to provide a synthetic resin molding method capable of performing injection or extrusion molding at a molding pressure significantly lower than that of the conventional method. To do.

[Means for solving problems]

Thus, the above-mentioned purpose is to send the molding material into the cavity as a minimum pressure necessary for economical operation, and to send the molding material into the cavity of the mold. This is achieved by applying a pressure shock wave to the molding material passing through the material inflow passage at a repetition frequency of 100 to 500 Hz so that the molding material is completely filled in the cavity and injection or extrusion molding is performed.

Here, the minimum pressure required for economical operation is an appropriate pressure at which the molding material can be fed into the cavity at an economical speed in view of operation efficiency, and the molding material is used during molding by the conventional method. The maximum pressure to be applied, that is, the pressure significantly lower than the molding pressure.

[Action]

According to the above method, the thixotropic action of the pressure shock wave applied to the molding material increases the fluidity of the molding material, and the pressure shock wave causes the molding material to be completely filled in every corner of the mold. The desired molding can be performed at a molding pressure significantly lower than the molding pressure required by the conventional method, and the pressure resistance and required power of the molding apparatus can be reduced.

〔Example〕

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

The drawings are explanatory views showing an example of an apparatus for carrying out the method according to the present invention, in which 1 is a screw type extrusion apparatus 2, an injection cylinder apparatus 3, an injection molding die apparatus 4 and these. The molding apparatus comprises a controller 5 including a numerical controller for controlling

In the drawings, the shock wave applying device 57 is exaggeratedly drawn in a large size, and in reality, a much smaller device is sufficient.

The screw type extrusion device 2 includes a cylinder 6, a screw 7, a breaker plate 8, a wire net 9, and heating coils 10,1.
0, nozzle 11, check valve 12, replenisher 13, compactor 14, motor 15, encoder 16, motor 17, encoder
18 and an inverter 19.

In addition, in the case of this embodiment, the injection cylinder device 3 is configured so as to accurately perform a predetermined amount of injection by receiving a predetermined unit injection amount of molding material for each injection. 20,21, Cylinder head 22,23,2
4, piston 25, 26, piston rod 27, automatic valve 28, 29,
Consisting of a nozzle 30, a heating coil 31 and an inverter 32,
The internal volume space formed by the cylinder tube 20, the head 22, and the piston 25 that receives, fills, and injects the molding material, and is injected is made to have a precise predetermined amount.

The injection molding die unit 4 includes a table 33 and guide shafts 34,3.
4, fixed plate 35, nuts 36, 36, mounting plate 37, heat insulating plate 38, receiving plate
39, spacer block 40, bush 41, mold valve 42, lower mold 43, heating coils 44,44, upper mold 45, heating coils 46,4
6, guide receiving plates 47, 47, upper die mounting plate 48, feed screw 49, motor 50, motor bracket 51, slider 52, slider receiving plate
53, slider guide plate 54, encoder 55 and inverter
Composed of 56.

First, the screw type extrusion device 2 will be described.

The motor 17 has its drive shaft connected to the rear end of the screw 7, and is provided with an encoder 18 for rotating the screw 7 and detecting changes in the amount of rotation and motor torque.

The screw 7 is rotatably provided in the cylinder 6, and is rotated by the drive of a motor 17 to send out plastic pellets, which is a molding material supplied from the replenisher 13, to the heating section, and at the same time, shearing that occurs at that time is sent. The molding material is heated by heat, and the molding material that is heated and pressurized in the heating section to become plastic is injected from the nozzle 11 provided at the tip of the cylinder 6 through the check valve 12 for the fixed quantity injection of the injection cylinder device 3. It is pushed out into the cylinder tube 20.

A breaker plate 8 having a large number of holes and a wire net 9 held by the breaker plate 8 are provided between the tip of the screw 7 and the nozzle 11 to make the flow of the molding material uniform so that the molding material is well kneaded and heated. Is made uniform.

The replenisher 13 is attached to the upper part of the cylinder 6 and supplies compressed plastic pellets, which is a molding material, in the cylinder 6 by a compactor 14 and a motor 15 and is provided with an encoder 16 for detecting the rotation amount thereof. Has been.

A plurality of heating coils 10, 10 are provided in the cylinder 6 surrounding the screw 7, and electric power is supplied from an unillustrated power supply device via the inverter 19 to heat the cylinder 6.

The portion of the cylinder 6 where the heating coils 10, 10 are provided constitutes a heating portion, and the molding material is heated by heat conduction from the inner peripheral surface of the cylinder 6 in this heating portion.

The nozzle 11 has a check valve 12 and is attached to the tip of the cylinder 6.

Then, when the molding material is supplied from the replenishing device 13 into the cylinder 6, the screw 17 is rotated by the driving of the motor 17, and the thermoplastic molding material is sent to the heating portion of the cylinder 6 to be heated by this. , Pressurized and fluidized, and further from the nozzle 11 attached to the tip of the cylinder 6 to the check valve 12
Is injected into the cylinder tube 20 for constant volume injection via.

Next, the injection cylinder device 3 will be described.

The injection cylinder device 3 has pistons 25 and 26 slidably provided in the cylinder tubes 20 and 21, respectively.
Attached in series to the openings of both ends of 0, 21 via the cylinder heads 22, 23, 24 respectively, slidably inserted in the holes provided in the cylinder head 22, and attached one end to the piston 25 and the other end to the piston 26. Piston rod 27 is provided, and automatic valves 28 and 29 for operating the piston 26 are provided at both ends of the outer circumference of the cylinder tube 21, respectively, and the nozzle 30 is provided on the cylinder head 22.
Install the inverter 32 around the cylinder tube 20.
From the power supply device (not shown) to heat the cylinder tube 20 and to provide a heating coil 31 for maintaining the molten state of the molding material.

In the operation of the injection cylinder device 3, at the beginning of each cycle, the pistons 25 and 26 are at the right end of the movement in the cylinder tubes 20 and 21, respectively, and the molten molding material is injected from the nozzle 11 into the cylinder tube 20. In synchronism with the above, the hydraulic pressure is supplied from the hydraulic unit (not shown) into the cylinder tube 21 by the operation of the automatic valves 28 and 29, and the piston 26 is moved to the piston rod.
The molding material is injected until it accurately moves to a predetermined position such as the left end of the movement along with the piston 25 via 27, and the amount of the injection molding material is always a predetermined amount. There is.

Next, the piston 25 is supplied with hydraulic pressure from a hydraulic unit (not shown) by the operation of the automatic valves 28 and 29 and moves together with the piston 26 through the piston rod 27 to the end of the movement in the direction of the cylinder head 22 to transfer the molding material to the nozzle 30. The following is a description of exactly what is formed by injection into the cavity of the injection molding die device 4 described below from a cylinder tube 22, that is, the tube 20, the head 22 and the piston 25. The product space is a precise scale or box for injecting the molding material into the next mold device 4.

Then, the injection molding die apparatus 5 of the molding apparatus 1 will be described.

The lower die 43 has heating coils 44, 44 inside, and the table 3
3 above mounting plate 37, heat insulating plate 38, receiving plate 39, spacer block 4
It is fixed via 0 and the bush 41.

Also, a sprue that passes the molten molding material from the nozzle 30,
Mold valve 42 provided by runner in backing plate 39 and bush 41
It is provided so as to communicate with the inside of the cavity of the lower mold 43 via.

The upper die 45 is movably supported by guide shafts 34, 34, a fixed platen 35, an upper die mounting plate 48 and a feed screw 49, and has heating coils 46, 46 therein. In the cavity of the mold 43, there is a protrusion for obtaining a molded product of a desired shape.

A plurality of heating coils 44, 44 and 46, 46 are provided inside the lower die 43 and the upper die 45, and the lower die 43 and the upper die 45 are supplied with power from an unillustrated power supply device via the inverter 56. Heat
This is for cooling the lower mold 43 and the upper mold 45 and molding after the molten molding material is evenly distributed to each part in the mold cavity.

The heat insulating plate 38 prevents the heat of the lower mold 43 from escaping to the table 33.
It is mounted between the receiving plate 39 and the mounting plate 37.

The upper die 45 includes a fixed platen 35 attached to the upper ends of four guide shafts 34, 34 which are vertically installed on the table 33 so as to straddle the lower mold 43, and a screw hole provided in the fixed platen 35. The feed screw 49 to be screwed together and the feed screw 49 are movably attached to one end of the feed screw 49 via an upper die mounting plate 48 provided so as to be rotatable and axially locked, and the motor 50 is The rotation shaft is attached to the feed screw 49, and is erected on the fixed platen 35.
It is slidably attached by a slider 52 and a slider receiving plate 53 via 51.

Further, the upper die 45 moves the feed screw 49 along with the screw hole of the fixed plate 35 screwed to the feed screw 49 by the rotation of the feed screw 49 by the drive of the motor 50, and thereby the four guide shafts 34. , 3
4 is used as a guide to move up and down between predetermined positions, and mold clamping is performed so as to form a mold cavity for obtaining a desired molded product at a position where it is superposed on the lower mold 43.

Thus, the control device 5 including the numerical control device is the molding device 1
The screw type extrusion device 2, the injection cylinder device 3 and the injection molding die device 4 are automatically controlled as a whole.
The operation will be described.

First, the control device 5 supplies the molding material from the replenishing device 13 into the cylinder 6 by controlling the driving motor 15 of the compactor 14 of the screw type extrusion device 2 and the encoder 16.
The screw 7 is rotated by the control of 17 and the encoder 18, and the molding coils are heated and melted by controlling the heating coils 10 and 10 via the inverter 19, so that the cylinder 7
The molten molding material is injected into the cylinder tube 20 of the injection cylinder device 3 by a predetermined amount from the injection port of the nozzle 11 at the tip of the.

Further, the control device 5 synchronizes with the injection of the molten molding material into the cylinder tube 20 heated by the control of the heating coil 31 through the inverter 32 in advance, and the automatic valve 28 of the injection cylinder device 3 is synchronized. Piston 25,26 by controlling 29,29
Is moved from the right end of movement to a predetermined position such as the predetermined end of movement shown in the left figure to inject a predetermined amount of molding material, and then the pistons 25, 26 are shown in the figure by the control of automatic valves 28, 29. The mold clamping motor is moved in advance from the position shown to the right and by controlling the mold valve 42 of the injection molding mold device 4.
The upper die 45 is moved by the control of the 50 and the encoder 55, the die is clamped on the lower die 43, and the lower die heated by the control of the heating coils 44, 44 and 46, 46 via the inverter 56.
Into the cavity of the upper mold 45 and the upper mold 45, the molten molding material measured in a predetermined amount by the cylinder tube 20 is
Inject from 30 and stop heating under pressure, lower mold 43 and upper mold 45
Is naturally or cooled by a cooling device (not shown).

Thus, in the method according to the present invention, the lower mold as described above is used.
During the period of injecting the molding material from the injection cylinder device 3 into the cavity between the 43 and the upper mold 45, 10
A pressure shock wave having a repetition frequency of 0 to 500 Hz is applied.

That is, in the illustrated apparatus, the shock wave imparting device 57 applies a pressure shock wave to the molding material in the flow path leading from the nozzle 30 of the injection cylinder device 3 to the cavity of the mold. The shock wave imparting device 57 includes a housing 58 attached to the receiving plate 39, an armature 59 slidably accommodated in the housing 58, and the armature 59.
The rod 60 fixed to the 59, the pushing spring 61, the electromagnetic coil 62, and the inverter 63, the tip of the rod 60,
The injection cylinder device 3 is inserted into a side passage 39 ″ that communicates with a molding material flow passage 39 ′ that communicates with the mold cavity from the nozzle 30.

When a current is passed through the electromagnetic coil 62, the armature 59 is pulled into the electromagnetic coil 62 against the pushing force of the pushing spring 61, and the rod 60 moves leftward in the drawing in the side passage 39 ″, and the die The pressure of the molding material filled in the cavity is rapidly increased, so that by interrupting the current to the electromagnetic coil 62, a pressure shock wave having a desired frequency is applied to the molding material filling the cavity.

Therefore, when injecting the molding material from the injection cylinder device 3 into the cavity between the lower mold 43 and the upper mold 45, the control device 5 sends a control signal to the inverter 63, and the inverter 63 sends the electromagnetic coil 62 a frequency of 100 to 500 Hz. It is controlled to supply a current having a repetition frequency, whereby a pressure shock wave having a repetition frequency of 100 to 500 Hz is applied to the molding material filled in the cavity.

In that case, the thixotropic phenomenon occurs in the molding material due to the pressure shock wave having the above-mentioned repetition frequency, which increases the fluidity of the molding material, and the pressure shock wave causes the molding material to completely spread to every corner of the mold. Because it is filled in
The desired molding can be carried out at a molding pressure significantly lower than the molding pressure required by the conventional method.
Therefore, the pressure resistance and required power of the molding apparatus can be reduced.

The frequency of the pressure shock wave is preferably about 100 to 500 Hz. If the frequency is 100 Hz or lower, sufficient fluidization of the molding material cannot be obtained, and if it is 500 Hz or higher, the shock wave imparting effect does not further increase.

The molding material can be applied to either thermoplastic or thermosetting resins, and is particularly effective for composite resins. For example, a phenol resin containing 30% by weight of glass fiber is injected into a mold at 170 ° C through an injection cylinder device heated to 210 ° C to obtain 200cc.
460k when pressure shock wave is not applied when molding
Although a molding pressure of g / cm ² was required, it became possible to mold at a molding pressure of 110 kg / cm ^{2 when} a pressure shock wave of 180 Hz was applied.

The molding pressure of 460 kg / cm ² according to this conventional method is a pressure applied to the molding material after the molding material is filled in the mold and before the molding is completed.

On the other hand, the molding pressure of 110 kg / cm ² according to the method of the present invention is
In this example, the pressure is required to fill the mold with the molding material at an industrially appropriate speed, and is applied to the molding material until the molding is completed.

Thus, in molding by the conventional method under the same conditions as in this example, it is usually impossible to completely fill the cavity with the molding material at the above pressure of about 110 kg / cm ^2. Therefore, the pressure is increased to about 460 kg / cm ² .

However, in the present invention, instead of increasing the molding pressure, a strong pressure shock wave is applied to the molding material, whereby the molding material is completely filled in every corner of the mold.

Therefore, in the present invention, it is not necessary to increase the molding pressure for filling the molding material, and molding can be performed at a pressure low enough to inject or extrude the molding material at an appropriate speed.

If this molding pressure becomes too low, the filling speed of the molding material into the mold decreases, not only the economical operation efficiency cannot be maintained, but also the quality of the molded product becomes problematic. On the contrary, to put more pressure on it is a waste of power cost and is useless.

Therefore, in the present invention, it is not necessary to determine the molding pressure in consideration of completely filling the molding material into every corner of the mold, and the composition and fluidity of the molding material, the purpose of molding, the molding apparatus This is determined so that molding can be performed at an industrially appropriate speed, taking into consideration types and capabilities.

The mounting position of the shock wave imparting device 57 is not limited to that shown in the figure, and for example, the shock wave imparting device 57 may be attached to the side wall of the cylinder tube 20 of the injection cylinder device 3 to impart a pressure shock wave to the molding material in the cylinder tube. Alternatively, or alternatively, the pressure shock wave may be applied at any position in the flow path leading from the nozzle 30 to the cavity of the mold.

Further, the structure of the shock wave imparting device 57 is not limited to the solenoid type using the electromagnetic coil, but the rod 60 may be driven by any other desired means, or a pressure shock wave using a magnetostrictive element or the like. May be added.

〔The invention's effect〕

Since the present invention is configured as described above, according to the present invention, the flowability of the molding material is increased by the pressure shock wave applied to the molding material, and the desired molding is performed even at a relatively low molding pressure. It is also possible to reduce the pressure resistance of the molding device.

It should be noted that the apparatus for carrying out the method according to the present invention is not limited to the above embodiments, and includes all modified embodiments that can be easily conceived by those skilled in the art from the above description. It is a thing.

[Brief description of drawings]

The drawings are explanatory diagrams showing an example of an apparatus for carrying out the method according to the present invention. 1 …… Molding device 2 …… Screw type extrusion device 3 …… Injection cylinder device 4 …… Injection molding die device 5 …… Control device 6 …… Cylinder 7 …… Screw 8 …… Breaker plate 9 …… Metal mesh 10 …… Heating coil 11 …… Nozzle 12 …… Check valve 13 …… Replenisher 14 …… Compactor 15 …… Motor 16 …… Encoder 17 …… Motor 18 …… Encoder 19 …… Inverter 20,21 …… Cylinder tube 22,23,24 …… Cylinder head 25,26 …… Piston 27 …… Piston rod 28,29 …… Automatic valve 30 …… Nozzle 31 …… Heating coil 32 …… Inverter 33 …… Table 34 …… Guide shaft 35 …… Fixing plate 36 …… Nut 37 …… Mounting plate 38 …… Insulating plate 39 …… Receiving plate 40 …… Spacer block 41 …… Bushing 42 …… Type valve 43 …… Lower die 44 …… Heating coil 45 ...... Upper mold 46 …… Heating coil 47 …… Guide Plate 48 …… Upper die mounting plate 49 …… Feed screw 50 …… Motor 51 …… Motor bracket 52 …… Slider 53 …… Slider receiving plate 54 …… Slider guide plate 55 …… Encoder 56 …… Inverter 57 …… Shock wave Applicator 58 …… Housing 59 …… Armature 60 …… Rod 61 …… Extrusion spring 62 …… Electromagnetic coil

Claims (1)

[Claims] 1. A method of molding by injecting or extruding a molding material into a mold, wherein the molding material is fed and filled into a cavity between the molds (43, 45) at a low molding pressure, and
It is possible to apply a pressure shock wave to the molding material passing through the material inflow passage (39 ') to the mold device (4) at a repetition frequency of 100 to 500 Hz to completely fill the molding material into the cavity and perform molding. The above-mentioned synthetic resin molding method characterized by the above.