JPH0976298A - Cassette type injection molding die device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automate the color changeover of a molding resin. SOLUTION: When color is changed from a molding resin of a first color into the same of a second color, a cassette mold is changed into a cassette mold for purging, whose shot volume is increased, by a mold changing means 4, changing the cassette mold automatically, to effect purge work. When the resin of the first color is removed by the purge work, the mold is changed into the cassette mold for molding again by a mold changing means 4 to mold while injecting the resin of the second color from an injection means. Respective means, including a color changing means 4, for changing the resin of first color into the resin exclusive for purging or the resin of second color, a mold opening and closing means 1, advancing or retreating the mold, and the like, are controlled by a control circuit 5 while the color changing work is automated as one of injection molding works. The already provided mold changing means can be utilized whereby the propulsion of automation of the color changing work can be contrived.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette type injection molding die device.

[0002]

2. Description of the Related Art Plastic injection-molded products are lighter than metal and can be mass-produced in complicated shapes, so that they can be used as various members and can be colored in desired colors. It also occupies an important position in terms of.

By the way, the method of coloring an injection-molded product is roughly classified into a method in which a resin material (pellet) as a raw material is colored in advance with a pigment having a desired color, and this is supplied from a hopper to an injection molding machine. Injecting liquid color in parallel with supplying colored pellets from the hopper to the injection molding machine,
A method of uniformly coloring while stirring with a screw conveyor in an injection molding machine is adopted.

In any case, when the coloring of a molded product is changed (color change) with the same mold, the coloring in the preceding stage (color A) and the coloring in the succeeding stage (color B) must not be mixed. Before molding a B-color molded product, it is necessary to completely discharge (purge) the A-color so that the B-color resin is completely discharged.

In the purging work, for example, the nozzle is retracted from the mold, and the color A is injected aiming at the inlet of the sprue bush. However, in this method, the purged resin collects at the inlet of the sprue bush, and it is necessary to manually remove it, which makes automation of the color changing operation difficult.

As a first example of countermeasures against this, the applicant of the present invention first made a shield plate enter between the nozzle and the mold at the time of purging work, and applied the purged resin to the shield plate, It has been proposed to drop it from the container and collect it in a collection container (JP-A-59-48739).

Further, as a second example, the present applicant sends a signal to stop the supply of the resin material of A color and to start the supply of the resin material of B color after the molding quantity of A color reaches a certain count number. Emitting detection means and a nozzle retreat signal, advance the shield plate that receives the purged resin material after the nozzle retreat,
Further, there has been proposed an injection molding apparatus capable of continuous automatic molding including a drive means for retracting the shielding plate after a predetermined number of automatic purging (Japanese Utility Model Publication No. 62-37707).

As a third example, there is a color changing method in an injection molding apparatus for injecting a liquid color into colorless pellets to obtain a desired colored molded article, for example, Japanese Patent Publication No. 2-570.
No. 07 publication.

The outline of this proposal is as follows:
Before the color is supplied, the maximum back pressure is applied to the screw of the injection-molded material to increase the extrusion pressure for the raw material for continuous injection molding, and the liquid color is increased compared to that during normal injection molding to mix the two. In this state, push out from the mixing nozzle to clean the gap between the tips of the injection molding machine. Next, reduce the back pressure, inject the liquid collar with the mixing nozzle closed, retract the screw to the calculation state, and push it out from the mixing nozzle again, so that the cleaning between the casing and the screw is done at once. The above process is repeated a predetermined number of times to quickly change colors.

[0010]

The first example of the prior art described above has the disadvantage that it is not suitable for the automation of color change because it requires the intervention of an operator for the purging operation. In the second example,
On the other hand, while the automation of color change is advancing, there is a cost problem because various means for that purpose must be provided. Further, in the case of the third example, since careful purging is performed, waste of the purging material for color change is reduced and the efficiency of color change is improved, but
There is a problem of cost increase due to complicated structure and operation.

Therefore, an object of the present invention is to use an existing cassette mold automatic changing device to perform a color changing operation by replacing the color changing work with a purging mold and purging. An object is to provide an injection molding die device.

[0012]

In order to achieve the above object, the present invention provides a cassette-type injection mold apparatus for performing a molding operation by mounting a replaceable cassette mold on a base plate of an injection molding machine. In the case of changing the color of the molding resin of the first color to the molding resin of the second color, during the supply of the purging resin, a purging cassette mold having a larger shot volume than the molding product cassette mold is used. It is characterized in that the purging work can be speeded up by exchanging and purging work.

The present invention further includes a mold opening / closing means for opening / closing the cassette type injection molding die device, and an injection means for supplying a molding resin to the cassette die mounted on the cassette type injection molding die device. The control system is provided with mold changing means for automatically changing the cassette mold, color changing means for changing the color of the molded product molded by the cassette-type injection molding mold device, and a control circuit for controlling each means. The circuit, when changing the color of the molding resin of the first color to the molding resin of the second color,
The mold exchanging unit replaces the molded product cassette mold with the purging cassette mold, and the color changing unit switches the molding resin of the first color to the purging resin to perform the purging operation. The purging cassette mold is replaced with a molding product cassette mold, and the color changing means is controlled to switch the purging resin from the purging resin of the second color to the molding resin of the second color to perform the molding operation. It is characterized by the fact that it realizes automation of injection molding work including.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of an injection molding apparatus of the present invention. A mold for automatically exchanging a cassette mold into a basic structure of an injection molding machine including a mold opening / closing means 1, an injection means 2 and a color changing means 3. The exchange means 4 is provided, and each of these means can be controlled by a control circuit (CPU) 5. The control circuit 5 has a memory circuit 6 in which a molding program and a color changing program are stored in advance.
Is connected so that stored data can be exchanged.

The mold opening / closing means 1 is a molding apparatus main body (not shown).
With the cylinder provided in the above, the mold opening and mold closing operations are performed by advancing and retracting the movable side mold of the cassette type injection molding mold device as shown in FIGS.

The injection means 2 is composed of a casing for heating the resin material (pellets) supplied from the hopper also provided in the main body of the molding apparatus and sending it in a molten state, and an injection nozzle provided at the tip of the casing. Become. A screw conveyor is provided in the casing, and the pellets are heated to be a molten resin while being fed by the screw conveyor.

The color changing means 3 is a combination of two or more hoppers containing the already colored pellets and a hopper containing the purging resin, and a switching means for switching the supply paths of these hoppers. Consists of. When the resin of the first color is switched to the resin of the purging and the resin of the purging is supplied to completely wipe off the resin of the first color remaining in the casing and the injection nozzle, the resin of the second color is changed. It is configured to be switchable for supply.

The mold exchanging means 4 is an automatic cassette die exchanging device capable of automatically attaching and detaching a cassette die to and from a cassette die accommodating concave portion provided on each base plate.

The control circuit 5 is for controlling each of the above-mentioned means by a molding command signal input from an external input means (not shown), and by exchanging data stored in the storage circuit 6 in advance. Each means can be controlled.

FIG. 2 is a cross-sectional view of a typical three-plate type cassette type injection molding die apparatus capable of separating and collecting the runner and the molded product (product) of the present invention when viewed from above in a mold open state. .

As shown in FIG. 2, the cassette type injection molding die apparatus according to the present invention comprises a fixed side die P and a movable side die Q. A plurality of cassette molds 11 and 12 having different cavity portions 11d and 12d for each molding are replaceably inserted.

The fixed side mold P and the movable side mold Q are four guide shafts 21 fixed to the fixed side mold P side during mold clamping.
Four guide bearings 2 (only one is shown in FIG. 2) are provided on the movable side base plate 20 on the movable side mold Q side.
0a (only one is shown in FIG. 2) is inserted and guided.

First, the fixed mold P will be described. A fixed side receiving plate 14 is fixed to the front surface (left side in the drawing) of the fixed side mounting plate 13, and a runner stripper plate 15 and a fixed side base plate 16 are arranged in this order on the front side of the fixed side receiving plate 14. ing.

On the fixed side mounting plate 13, a sprue bush 22 having a sprue 22a is formed.
It is attached through. A nozzle (not shown) of a molding machine is fitted to the sprue bush 22. Further, four support shafts 24 are fixed to the fixed side mounting plate 13 (only one is shown in FIG. 2). The fixed-side mounting plate 13 is provided with a runner lock pin 25, the tip of which is formed in an undercut shape and which reaches the runner portion 11f of the fixed-side cassette mold 11. Fixed side base plate 1
6 and the runner stripper plate 15 are provided with four support bearings 15a and 16a (only one is shown in FIG. 1). Fixed side base plate 16
Also, four support shafts 24 are inserted through the four support bearings 15a and 16a of the runner stripper plate 15, respectively.
The runner stripper plate 6 and the runner stripper plate 15 are slidably supported by the fixed-side mounting plate 13 and the fixed-side receiving plate 14.

In this embodiment, the fixed-side base plate 16 has a total of four fixed-side cassette mold accommodating recesses with two rows in the left-right direction and two steps in the up-down direction at a predetermined interval in the thickness direction. 16b is opened with the same rectangular sectional shape. The fixed-side cassette mold 11 is inserted into the fixed-side cassette mold storage recess 16b. The fixed-side cassette mold 11 has the fixed-side base plate 16 in a state where the front flange portion 11b is locked to the fixed-side base plate 16.
Fixed side cassette die storage recess 1 vertically on the back side of the
Key groove 1 formed so as to overlap with 6b
The fixed key 26 is inserted in 6c.
The rear brim portion 11c is locked and fixed to the.

The fixed-side cassette mold 11 is provided with a gate portion 11e communicating with the runner portion 11f on the molding surface, and molten resin is injected from this gate portion into the cavity portions 11d and 12d formed during mold clamping. Is filled. Further, on the front flange portion 11b of the stationary-side cassette mold 11, two guide pins 11 (only one is shown) are provided on a diagonal line of the mold surface.
a is planted in the movable side cassette mold 12 which will be described later.
, And guides the opening / closing of the fixed mold P and the movable mold Q on a cassette mold unit basis when the fixed mold P and the movable mold Q are opened / closed.

Between the runner stripper plate 15 and the fixed side base plate 16, several limiting bolts 27 are provided.
(Only one is shown in FIG. 2). The limiting bolt 27 limits the plates 15 and 16 from opening beyond a certain width. The tip portion of the limiting bolt 27 is attached to the front surface of the runner stripper plate 15 by the stop bolt 27a so that the movement thereof can be limited, and the runner stripper plate 15 and the fixed side base plate 16 can be separated.

Fixed base plate 16 and movable mold P
Of the movable side base plate 20 of the tension links 31, 31
Are connected by When the mold is opened from the clamped state, the tension link 31 opens between the runner stripper plate 15 and the fixed side base plate 16 to the range of the limiting bolt 27, and the fixed side base plate 16
The tension link 3 is provided between the movable base plate 20 and the movable base plate 20.
When the movable side mold Q is moved to the range of 1 (moving away from the fixed side mold P) to the fixed side mold P,
The runner stripper plate 15 urged by the stationary side receiving plate 4 is finally moved.

Next, the movable die Q will be described. The movable mold Q is attached to a movable member (not shown) of the molding machine, and can move forward and backward with respect to the fixed mold P.
The spacer block 18 is in contact with the front surface (right side in the drawing) of the movable side mounting plate 17, and the movable side receiving plate 19 and the movable side base plate 2 are on the right side of the spacer block 18.
0 is abutted in that order.

Fixed side base plate 16 of fixed side mold P
Similarly, the movable side base plate 20 has a total of four movable side cassette mold accommodating recesses 20b having two rows in the left-right direction and two steps in the up-down direction with a predetermined interval in the thickness direction, and having the same rectangular cross section. It has been opened. The movable cassette mold 12 is mounted in the movable cassette mold storage recess 20b. Like the fixed-side cassette mold 11, the movable-side cassette mold 12 is also attached to the movable-side base plate 20 by the front flange portion 1.
In the state in which 2b is locked, the movable-side cassette mold accommodating recess 20b is vertically arranged in the surface direction on the back side of the movable-side base plate 20.
Key groove 20c formed so as to overlap with
A fixed key 32 is inserted into the fixed key 32, and the rear flange portion 12c is locked and fixed to the fixed key 32.

The movable side cassette mold 12 includes a bottom plate 12f,
Receiving plate 12g, spacer plate 12h, first template 12
i and the second template 12j are fixed in this order. The bottom plate 12f is elongated in the left-right direction with respect to the receiving plate 12g, and this portion serves as a rear brim portion 12c.
The second template 12j corresponds to the front brim 12b, the cavity 12d is formed in the second template 12j, and the core pin 12e is attached. Also, the second template 12j
The guide pin 11 of the fixed-side cassette mold 11 described above.
A guide bush 12a is provided at a position facing a.

A first ejecting mechanism is provided in the movable cassette mold 12. The first ejection mechanism is the first
The ejector plates 12k and 12l, the first ejector pin 12m fixed to the first ejector plates 12k and 12l, and the return pin (not shown). The first ejecting mechanism is housed in the space formed inside the spacer plate 12h, and the first ejector pin 12m is located in this space and the second ejector pin 12m.
The molded product W formed in the cavity 12d can be pushed down because it is slidably supported in a through hole that connects the cavity 12d of the template 12j. A return pin is provided in the space other than the cavity portion 12d of the second template 12j and the first ejector pin 12m.
And the first ejector plates 12k and 12l and the first template 12i of the return pin.
A return spring (not shown) made up of a compression coil spring is provided between the first ejector plate 12 and
The k and 12l are biased in the backward direction.

In order to move the first ejecting mechanism forward and backward, the second ejecting mechanism is arranged in the space provided by the spacer block 18 between the movable side mounting plate 17 and the movable side receiving plate 19. The second ejecting mechanism includes second ejector plates 33a and 33b, and second ejector pins 34 and return pins (not shown) fixed to these ejector plates. In the second ejecting mechanism, the second ejector pin 34 is formed through the through hole 19a formed in the movable side receiving plate 19 and the bottom plate 12f of the movable side cassette mold 12 and the through hole 12n formed in the receiving plate 12g. The first ejector plates 12k and 12l are arranged so that they can enter and protrude.
The return pin is provided with a return spring and urges the second ejector plates 33a and 33b in the backward direction.

A through hole 17 is provided at substantially the center of the movable side mounting plate 7.
a is provided, and the ejector rod of the molding machine can move back and forth.

Next, the operation will be described. First, the pellets made of the resin of the first color are supplied to the hopper, and the control circuit 5
When the molding command signal S is input to, the color changing means 3 selects the hopper containing the resin, and then the control circuit activates the cylinder of the molding machine body, which is the mold opening / closing means 1, to move the movable mold Q back and forth. (See FIG. 1). The movable side mold Q moves to the right by the cylinder of the main body of the molding machine, and the front surfaces of the fixed side cassette mold 11 and the movable side cassette mold 12 come into contact with each other to be in a mold clamped state. By the mold clamping, cavities defined by the cavity portions 11d and 12d are formed on the parting line surfaces of both molds. The runner portion 11f communicates with this cavity, and the molding resin injected from the injection nozzle fitted to the sprue can be injected.

When the control circuit 5 outputs an injection command signal to the injection means 2 at the time of mold clamping, the resin of the first color (for example, black) is injected from the injection nozzle, and the sprue 22
The cavity is filled via a, the runner portion 11f, and the gate portion 11e.

After taking a predetermined curing time,
When the movable side mold Q is retracted and the mold opening operation is started, gate cutting is performed while the molded product is left inside the cavity portion 12d of the movable side cassette mold, and the runner and the molded product are separated. When the movable mold Q further retracts, the ejector rod (not shown) is passed through the through hole 17a of the movable mounting plate.
Is ejected, and the second ejector plates 33a, 33a
From behind the 3b, the ejector plate is prevented from retreating and is relatively advanced. Due to the relative advance of the second ejector mechanism, the first ejector mechanism also moves and advances. That is, the ejector pin 34 of the second ejector mechanism advances the ejector plates 12k and 12l of the first ejector mechanism to project the ejector pin 12m from the bottom of the cavity portion 12d, as shown by the two-dot chain line in FIG. The molded product W is pushed out of the mold as shown in FIG.

As the movable side mold Q moves backward, the fixed side mold P
The runner stripper plate 15 and the fixed-side base plate 16 start to open preferentially by a compression coil spring (not shown), and the runner is left on the front surface of the runner stripper plate 15 by the runner lock pin 25.

When the movable side mold Q is further retracted and the fixed side base plate 16 is advanced by the pulling link 31, the runner escapes from the cassette mold 11 and is removed from the runner portion 11f. Here again, the cylinder serving as the mold opening / closing means 1 advances the cylinder to clamp the mold,
Move on to the next injection molding operation.

After molding the molded product of the first color (black) resin in this way, the molding of the molded product of the second color (eg, white) resin is started. The change (color change) from the A color to the B color is started by outputting a color change command signal from the control circuit 5 to the color change means 3 (see FIG. 1).

Simultaneously with the start of the operation of the color changing means 3, the control circuit 5 causes the mold changing means 4 to make the cassette dies 11 and 12 for molded articles.
Outputs a replacement instruction to the purge cassette molds 101 and 102.

As shown in FIG. 3, in the purging cassette molds 101 and 102, the cavity portion 102d of the movable cassette mold 102 is made larger than that of the molding mold so that the shot volume becomes large. I am doing it.
Further, although not shown, if the cavity portion is also provided in the stationary-side cassette mold 101, it is obvious that the shot volume is further increased.

The mold exchanging means 4 holds four fixed-side cassette molds 11 in a state in which they are previously fixed so as to be integrated,
By removing the fixed key 26 from the key groove 16c, the fixed key 26 is released from being fixed to the fixed-side mold P, taken out from the fixed-side cassette mold accommodating recess 16b of the fixed-side base plate 16, and cassette mold accommodating means (not shown). Transfer to and store. Next, the purging cassette die 101 is taken out from the cassette die accommodating means, inserted into the fixed-side cassette die accommodating recess 16b, and the fixing key 26 is inserted and fixed in the key groove 16c. Similarly, four movable side cassette molds 12
Is fixed in advance so as to be integrated with each other, and the fixed key 32 is pulled out from the key groove 20c so as to be released from being fixed to the movable side mold Q, and the movable side base plate 20 has a movable side cassette mold accommodating recess 20b. Then, it is transferred to and housed in a cassette die housing means (not shown).
Next, the purging cassette mold 102 is taken out from the cassette mold housing means, and the movable side cassette mold housing recess 20
Then, the fixed key 32 is inserted into the key groove 20c and fixed.

Next, when the mold is closed by the mold opening / closing means 1,
Purging cassette mold 102 and fixed-side cassette mold 1
A purging cavity having a shot volume larger than that of the molding product cassette die is formed on the parting line surface with 1. A purging resin is injected into the purging cavity from the ejection nozzle that is the ejection unit 2, and the purging cavity is filled with the resin. By injecting the purging resin into the purging cavity having a large shot volume, the solidified purging resin molded product Wp is several times larger than the actual molded product as shown by the chain double-dashed line. It is Therefore, the resin of the first color in the casing and the injection nozzle is wiped by the purging that is a fraction of the injection number for normal molding, and the preparation for switching to the resin of the second color is completed. . Since the molded product molded by purging is solidified in the cavity, it can be discharged in the same procedure as a normal molded product, that is, using the existing molded product take-out device, and the same as a normal molded product. Since it has surface gloss, it is possible to easily grasp the change in coloring and to manage coloring accurately.

When the purging operation by injecting the resin for exclusive use of purging by the purging cassette mold is completed, the purging cassette molds 101 and 102 and the molded product cassette molds 11 and 12 are exchanged again by the mold exchanging means 4. . After that, the injection molding operation is repeated by the mold opening / closing means 1 and the injection means 2 to inject the resin of the second color to mold the molded product of the second color.

The above-mentioned color changing means 3 is adapted to change over the colored resin hopper. When a coloring method is adopted in which the liquid color is injected into colorless pellets, May switch the connection of the liquid color supply pipe.

In the above embodiment, the purge operation is performed by exchanging the stationary cassette mold and the movable cassette mold as a pair as the purging cassette mold, but the cavity is formed. If there is no problem, if the purging operation is performed by exchanging only the movable side cassette mold from the molding cassette mold 12 to the purging cassette mold 102, the fixed side cassette mold 11 is replaced with the purging cassette mold 11. The time for replacing the mold 101 can be omitted, the cycle time can be increased, and the loss time due to the mold replacement can be reduced.

[0048]

According to the structure of the present invention, since the cassette die for the molded product is replaced with the purge cassette die having a larger shot volume than the cassette die for the molded product, the purging operation is performed, and therefore the molding operation is performed. It becomes possible to perform the purging work in the same procedure as the normal molding work by directly using the molded product takeout device for the purging work, and it is not necessary to provide a special device for the purging work. Further, since the shot volume of the purging resin is increased, the purging work can be performed quickly.

Further, when the present invention is applied to the one provided with the die exchanging means for automatically exchanging the cassette die, the existing die exchanging means can be used as it is, so that the purging cassette die and the molded article cassette die can be used. Since the exchange with the mold and vice versa can be performed without requiring special equipment, the color can be changed at low cost. Further, since the mold opening / closing means, the injection means, and the color changing means are controlled by the control circuit together with the mold changing means, the color changing work can be automated and the efficiency of the injection molding work can be improved. is there.

[Brief description of drawings]

FIG. 1 is a system block diagram showing the configuration of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a cassette mold for molded products is mounted on a cassette-type injection molding mold device.

FIG. 3 is a cross-sectional view showing a state in which a purging cassette mold is attached to a cassette-type injection molding mold device.

[Explanation of symbols]

 1 Mold Opening / Closing Means 2 Injection Means 3 Mold Replacing Means 4 Color Changing Means 5 Control Circuits 11, 12 Molded Product Cassette Molds 16, 20 Base Plates 101, 102 Purging Cassette Molds

Claims (2)

[Claims] 1. A cassette-type injection molding die apparatus for performing a molding operation by mounting a replaceable cassette die on a base plate of an injection molding machine, wherein a molding resin of a first color to a molding resin of a second color is used. When changing the color, during the supply of the purging resin, the cassette injection mold having a larger shot volume than the cassette mold for the molded product is replaced and the purging operation is performed. Mold device. 2. A mold opening / closing means for opening / closing the cassette type injection molding die apparatus, an injection means for supplying a molding resin to the cassette die mounted on the cassette type injection molding die apparatus, and the cassette. A die exchanging means for automatically exchanging a die, a color exchanging means for changing a color of a molded article molded by the cassette type injection molding die device, and a control circuit for controlling each of the means, The control circuit causes the mold exchanging means to replace the molded product cassette mold with the purge cassette mold when the first color molded resin is changed to the second color molded resin. The first by the color changing means
The molding resin having the above color is switched to the purging resin to perform the purging operation, and the purging cassette mold is replaced with the molding product cassette mold again by the mold exchanging means, and the purging is performed by the color changing means. A cassette-type injection molding die device, characterized in that control is performed such that the molding resin is switched from the molding resin to the molding resin of the second color.