JPH0780217B2 - Bent type molding machine resin changing device - Google Patents

Description

The present invention relates to a vent type injection molding machine and a resin changing device in a vent type extrusion molding machine.

(Prior Art) Conventionally, when changing materials, changing colors, or cleaning the inside of a screw and a cylinder in a vent-type injection molding machine, a new type is used from the drop opening of the hopper like a normal injection molding machine. The old resin is discharged by supplying the resin or the cleaning agent and plasticizing and discharging the resin or the cleaning agent. However, according to this method, the resin in the vent part of the screw is under reduced pressure, and since the resin is not filled in the groove, the old resin remains attached to the screw in the vicinity of the vent part, resin change, color change, The replacement or cleaning could not be performed completely. Therefore, in order to completely discharge the old resin,
A large amount of new resin or cleaning agent had to be supplied and discharged over a long period of time, which would cause a large amount of resin or cleaning agent to be wasted when changing resins, changing colors, or cleaning, and working time, etc. There was a drawback that the waste of money was extremely large.

For example, Japanese Utility Model Application Laid-Open No. 54-4277 discloses a resin changing device which eliminates such conventional defects and facilitates resin changing, color changing, washing, etc. in a vent type injection molding machine.

FIG. 2 shows the configuration of the resin changing device.

Generally, in a vent type injection molding machine, a screw 2 which is inserted into a cylinder 1 and is provided so as to be rotatable and slidable, has a raw material supply section A, a first compression section B, a first weighing section C, a vent in order from its base. A part D, a second compression part E and a second metering part F are formed, and a cylinder 1 is provided with a raw material resin hopper 3 at a position corresponding to the raw material supply part A of the screw 2 and a screw 2 of the screw 2 is provided. The vent opening 5 is provided at a position corresponding to the vent D.

In the resin changing device shown in FIG. 2, the degassing accessory generally attached to the vent opening 5 of the vent type injection molding machine having such a structure can be removed, and instead, a raw material supply auxiliary The hopper 4 can be attached.

By doing so, when changing the material, the hopper 3 for the raw material resin is used.
Also, the new material or the cleaning agent can be introduced from both the raw material supply auxiliary hopper 4 attached to the vent opening 5.

When the injection molding of a certain resin material is completed and the resin is changed, the color is changed, or the cylinder 1 and the screw 2 are to be washed, the deaeration accessory attached to the vent opening 5 of the cylinder 1 is used. Detachment, a raw material supply auxiliary hopper 4 is attached thereto, and a new resin or a cleaning agent is introduced into this auxiliary hopper 4 together with the raw material resin hopper 3, and both the dropping port and the vent opening 5 of the raw material resin hopper 3 are introduced. After that, it is supplied into the cylinder 1 and the screw 2 is rotated. The supplied new resin or cleaning agent in the cylinder 1 is transferred forward along the screw groove by the rotation of the screw 2. In this case, the new resin or cleaning agent in the vent part D is vented. Since the opening 5 is closed by the new resin or the like put into the auxiliary hopper 4, a back pressure is applied by the second compression portion E, the interparticle density is increased, and therefore the screw 2 violently comes into shear contact. In this way, the old resin adhering to the cylinder 1 and the screw 2 is peeled off from them, and is forwarded and discharged together with the new raw material or the cleaning agent.

(Problems to be Solved by the Invention) However, even the resin changing device shown in FIG. 2 has the following problems.

(1) In particular, when changing a resin from a high-viscosity resin to a low-viscosity resin, it is difficult to peel off the high-viscosity resin attached to the screw with the melted low-viscosity resin.

(2) Since the vent opening is controlled to a temperature suitable for the resin to melt and have a viscosity that allows the resin to be filled in the mold, the surface of the resin melts at the vent opening, resulting in a so-called "rice cake-like cake". "Because the resin has been changed, the vent opening must be cleaned again and the workability is poor.

(3) When the resin charged into the vent opening becomes a "plug-like" shape and becomes a kind of plug, the amount of resin sent from the first metering unit may vary depending on the screw rotation speed and back pressure conditions. In some cases, the amount of resin sent increases and the amount of resin sent in the vent portion decreases, which causes so-called vent-up, in which the plug-shaped resin rises and seals the vent opening.

The present invention has been made in order to eliminate such a problem, and has excellent workability at the time of resin change, etc., and the old resin adhering to the vicinity of the vent opening can be surely removed, and the resin change can be quickly performed. An object of the present invention is to provide a resin changing device that prevents the temperature from rising.

(Means for Solving the Problems) Therefore, the present invention is a resin changing device in a vent type molding machine having a raw material supply port and a vent opening in a cylinder, wherein a raw material resin hopper is connected to the raw material supply port, The vent opening is connected with a temporary resin hopper for storing a foamable resin, and switching means for switching the resin dropping openings of the raw material resin hopper and the temporary resin hopper to each other and the cooling of the vent opening. And means for providing the means for solving the above problems.

(Function) When changing the resin from the old resin to the new resin, open the drop port of the raw material resin hopper and fill the upstream side of the vent opening in the cylinder with new resin or purge material, and then drop the raw material resin hopper. While closing the mouth, cool the vent opening or the vent part or the vent part cylinder at both places, and at the same time open the drop port of the temporary resin hopper to supply the foamable resin from the vent opening to remove the resin in the cylinder. After plasticizing and discharging, the drop port of the temporary resin hopper is closed, while the drop port of the raw material resin hopper is opened to supply the new resin.

When the vent opening portion and / or the cylinder portion of the vent portion is cooled and the resin having foamability is supplied, the resin is sent to the front in the form of pellets, and the resin pressure in the cylinder is increased by the second compression portion. Foams and is plasticized and discharged.

At this time, the following actions occur.

(1) The resin adhering to the vent portion is scraped off by the pellet-like solid resin by the same action as the polishing action.

(2) Due to the pressure rise during foaming, the attached resin is shocked and separated from the attached portion.

(3) The foam does not adhere to the screw because the adhesive force on the surface of the resin decreases.

(4) The vent opening and / or the cylinder portion of the vent is cooled to prevent the vent opening from being blocked by the resin.

(5) Since the resin having the foaming property is introduced only into the vent opening, there is no case where the resin of the first metering unit joins and vents up unlike the conventional case.

(Example) Hereinafter, the present invention will be described in more detail based on illustrated examples.

FIG. 1 shows a plasticizing device of a molding machine equipped with a resin changing device which is a typical embodiment of the present invention, in which 1 is a cylinder,
Reference numeral 2 is a screw in which a raw material supply section A, a first compression section B, a first metering section C, a vent section D, a second compression section E, and a second metering section F are formed in this order from the base thereof. A vent opening 5 is formed at a position corresponding to the raw material supply portion A of the screw 2 and a position corresponding to the vent portion D and a hopper hole 6 into which the raw material resin is charged. An outlet of a raw material resin feeding pipe 18 is connected to the hopper hole 6, and an outlet of a temporary resin feeding pipe 19 sent from a temporary resin hopper described later is connected to the vent opening 5.

This raw resin injection pipe 18 and the temporary resin injection pipe 19
Are joined at the inlet thereof, and at the joining point, a switching device 16 including an electromagnetic valve or the like for switching the injection destination of the resin to either the vent opening 5 or the hopper hole 6 is attached.

Above the switching device 16, a resin supply port of a raw material supply device 15 that controls the rotation of the feed screw 13 by the electric motor 14 and controls the supply amount of resin is connected, and the resin input port of the raw material supply device 15 is connected to the resin input port. A pipe 17 for dropping the resin supplied from the raw material resin hopper 3 and the temporary resin hopper 10 is connected. Solenoid valves 11 and 12 for controlling ON / OFF of the dropping of the resin are provided at the respective drop openings of the raw material resin hopper 3 and the temporary resin hopper 10. The temporary resin hopper 10 is filled with a resin having foamability other than the molding raw material. Examples of the temporary resin having foamability include non-drying acrylic resin, non-drying acrylic resin and detergent, non-drying acrylic resin sprayed with water, and the like.

On the other hand, an outer cylinder 21 that circulates the air blown from the blower 20 is installed on the outer circumference of the cylinder 1 corresponding to the vent portion D.

Next, the operation will be described step by step.

(1) After the molding of the old resin is completed, the rotation of the electric motor 14 is stopped, the supply of the old resin by the feed screw 13 is stopped, and the resin remaining inside the cylinder 1 is plasticized and discharged. At this time, the switching device 16 directs the drop opening toward the hopper hole 6.

(2) New resin or purge material is charged into the raw material resin hopper 3, and new resin or purge material is supplied from the hopper hole 6 and plasticized and discharged. At this time, the first supply part A, the first compression part B, and the first metering part C are easily replaced with resin because the pressure is rising, but the vent part D is in the groove of the screw 1 in a reduced pressure state. However, the old resin adheres and remains because it is not filled.

(3) Here, the blower 20 is operated to cool the vent portion D, and the cylinder temperature is lowered to 140 to 160 ° C.

(4) The drop port of the switching device 16 is switched to the vent opening 5 side, and at the same time, the solenoid valve 11 at the drop port of the raw material resin hopper 3 is used.
Is turned off, and the solenoid valve 12 at the drop port of the temporary resin hopper 10 is
Turn on and rotate screw 2.

(5) The temporary resin hopper 10 having a foaming property is a temporary resin.
Is fed from the feed screw 13 to the vent opening 5 through the pipe 19 and is sent to the second measuring unit F by the rotation of the screw 2.

Here, the feed screw 13 is used to control the amount of resin supplied. When the vent opening 5 is tightly packed with resin, the phenomenon that the vent opening 5 is smaller than the hopper 6 and does not fall due to the solid frictional force of the pellet itself occurs. , To prevent this.

Therefore, when the resin drops, the feed screw is adjusted so that the gap can be seen about 20% when the vent opening 5 is viewed from above.
13 rotations are adjusted and supplied. At this time, since plasticization is performed from the vent portion D to the second measuring portion F in the same manner as in a normal molding machine, back pressure is applied to the vent opening portion 5 at the second compression portion E, and at the same time, the vent portion D is formed. The old resin adhering to the screw is stripped off in an extremely short time due to the friction-like scraping effect of the pelletized solid resin, the filling due to the resistance of the solid resin during transportation, and the resin foaming.

(6) Foamed resin is discharged from the tip of the cylinder.

(7) The drop port of the switching device 16 is switched to the hopper hole 6, the solenoid valve 11 is turned on, the solenoid valve 12 is turned off, and the cylinder temperature of the vent portion D is changed to the molding temperature.

(8) The screw 2 is rotated, the new resin supplied from the hopper 3 is plasticized and discharged, and then the normal molding operation is started with the new resin. The resin injected from the vent opening 5 has an advantage that the resin surface has a small adhesive force and does not adhere to the screw 2 by foaming, and has a foaming property when the new resin is injected from the raw material resin hopper 3. Facilitates resin replacement from resin to new resin.

Due to the above action, compared to the conventional method, the resin change from high viscosity resin such as PC Noryl to low viscosity resin such as PS nylon,
The color change from a dark color such as black to a light color such as white or transparent can be easily performed in an extremely short time.

For example, when molding flame-retardant PS resin after molding heat-resistant ABS resin, there were 3 black spot defects at the start,
Molding failure was 0 for 100 pieces.

(Effects of the Invention) According to the present invention as described above in detail, according to the present invention, when a resin is changed, a resin having foamability is charged from the vent opening portion prior to charging a new resin, and plasticized and discharged. (1) The old resin attached to the screw near the vent can be easily removed in a short time.

(2) The resin charged through the vent opening is foamed during plasticization, and is unlikely to adhere to the screw, and can be easily removed.

(3) Since the vent portion is cooled, it is possible to prevent the problem that the resin becomes clogged and blocked at the vent opening portion.

[Brief description of drawings]

FIG. 1 is a block diagram of a plasticizing section showing a typical embodiment of the present invention, and FIG. 2 is a block diagram of a plasticizing section equipped with a conventional resin changing device. Description of main parts of the figure 1 …… Cylinder 2 …… Screw 3 …… Raw material resin hopper 5 …… Vent opening 6 …… Hopper hole 10 …… Temporary resin hopper 11,12 …… Solenoid on-off valve 15 …… Raw material supply device 16 …… Switching device 20 …… Blower 21 …… Outer cylinder D …… Vent part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Tamura, Takaichi, Iwazuka-cho, Nakamura-ku, Nagoya-shi, Aichi Prefecture, Nagoya Research Institute, Mitsubishi Heavy Industries, Ltd. (72) Kiyoshi Kinoshita, Iwatsuka-machi, Nakamura-ku, Nagoya, Aichi Highway No. 1 Mitsubishi Heavy Industries, Ltd. Nagoya Research Laboratory (56) Reference JP-A-55-105543 (JP, A) Actually open 58-64420 (JP, U) Actually open 54-4277 (JP, U)

Claims (1)

[Claims] 1. A resin changing device in a vent type molding machine having a cylinder with a raw material supply port and a vent opening, wherein a hopper for a raw material resin is connected to the raw material supply port, and a foaming resin is provided in the vent opening. A vent characterized by connecting a temporary resin hopper to be stored and a switching means for switching between the resin dropping ports of the raw material resin hopper and the temporary resin hopper and a cooling means for the vent opening. Changer for automatic molding machines.