JP3235482B2 - Gate opening and closing device and gate opening and closing method in rotary injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for opening and closing a gate of a mold of a rotary injection molding machine and a method for opening and closing the gate.

[0002]

2. Description of the Related Art As a rotary injection molding machine, a gate pin for closing a gate is vertically movable at two rotation stop positions of a rotary table which is rotatable intermittently at a predetermined angle in a circumferential direction about a central axis. A molding station for clamping the upper mold provided to the lower mold on the rotary table with a mold lifting elevator and injecting resin from a nozzle of an injection device into molding cavities of both molds, and a mold opening elevator. In addition, there is known an apparatus in which an upper mold is fixed by a clamp, lifted, separated from the lower mold, and a take-out station for taking out molded products from the molding cavities of both molds is known (see, for example, Japanese Patent Laid-Open No. Hei 5-
No. 138683).

As shown in FIG. 8, the conventional gate opening / closing device of this rotary injection molding machine pushes down an upper / lower plate 20 on which a gate pin 19 is mounted to form a molding cavity C of a lower mold 5 and an upper mold 12. The molding cavity C is mainly composed of a gate cut cylinder 8 for closing the gate g, and an ascending coil spring 41 provided by urging the upper and lower plates 20 upward.
After the resin injected from the nozzle 14 of the injection device 7 through the gate g is hardened, the gate cut cylinder 8 is contracted to raise the gate pin 19 together with the upper and lower plates 20 by the coil spring 41. To open the gate g. The gate cut cylinder 8 is provided on a mold clamping lift board 10 for clamping the upper mold 12 to the lower mold 5 on the rotary table 1.

A conventional molding cycle at a molding station is shown in FIG. As can be seen from this figure, the injection device 7 measures (supplies) the next resin before the gate pin 19 is lowered, that is, before the gate cut, and after the injection resin is cured, the nozzle 14 is retracted so that the dies 5, 12.
Away from Then, the mold clamping elevator 10 is raised.

[0005]

In the conventional gate opening / closing device, if the gate cut cylinder 8 is reduced before the resin in the molding cavity C is completely cured, the gate pin 19 is raised by the action of the coil spring 41. Since the gate g is opened, the resin once cut by the lowering of the gate pin 19 may be connected again.

For this reason, the molds 5 and 12 cannot be transferred to the next station until the resin in the molding cavity C is cured to such a degree that the resin is not connected even when the gate g is opened.
Since the cycle time becomes long, there is a problem that the production efficiency cannot be increased.

An object of the present invention is to provide a gate opening and closing device in a rotary injection molding machine capable of transferring a mold to a next station in a state where the resin in a molding cavity is not completely cured. .

Another object of the present invention is to provide a gate opening and closing method in a rotary injection molding machine capable of shortening the cycle time and increasing the production efficiency.

[0009]

In order to achieve the above object, a gate opening and closing device in a rotary injection molding machine according to the present invention is intermittently rotatable at a predetermined angle in a circumferential direction about a central axis. At the two rotation stop positions of the rotary table, the upper die having a gate pin for closing the gate is vertically moved to the lower die on the rotary table with the lifting die for clamping. A molding station that injects resin from the nozzle of the injection device into the molding cavity, and an upper mold that is fixed to the mold opening and lowering plate with clamps, lifted up, separated from the lower mold, and molded products from the molding cavities of both molds. In a rotary injection molding machine provided with a take-out station for taking out, a locking means for locking the gate pin, which has been lifted to open the gate, on the gate pin,
A lowering means for unlocking the gate pin by the locking means and lowering the gate pin to close the gate at the molding station; an urging means for urging the gate pin downward to hold the gate closed; and A lifting means for raising the gate to open the gate and locking the locking means is provided.

The lowering means may be provided on the mold lifting elevator, and the lifting means may be provided on the mold opening elevator. Also, the gate pin can be attached to the upper and lower plates which can be lowered by the lowering means and raised by the raising means, and locking means can be provided between the upper and lower plates and the upper plate of the upper mold. Further, the urging means may be upper and lower plates for urging the gate pin downward by its own weight.

Further, according to the present invention, there is provided a method for opening and closing a gate in a rotary injection molding machine, the method comprising: Lower the gate pin locked by the means to close the gate,
While the gate is kept closed by the urging means, the rotary table is rotated in a state where the resin in the molding cavity is not completely cured, and the two dies are transferred to the next station.

In the above gate opening / closing method, the gate pin is raised by the lifting means at the take-out station and locked by the locking means, and then the rotary table is rotated to transfer both dies toward the molding station. It can be.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. 1 to 6 show an embodiment of a gate opening / closing device in a rotary injection molding machine according to the present invention. In these figures, reference numeral 1 denotes a rotary table. The rotary table 1 is intermittently rotated 90 degrees counterclockwise in FIG. 1 around the central axis 3 by a rotary drive device 2 such as a hydraulic motor, and the positioning pins 4 are inserted into the positioning holes 1a from below. It stops at a predetermined position.

At the four rotation stop positions of the rotary table 1, a molding station S1, a cooling station S
2. The unloading station S3 and the mold exchanging station S4 are arranged in the rotation direction of the rotary table 1 in the order described above. Rotary table 1 has 4
The lower mold 5 and the upper mold 12 are provided as a set at equal intervals.

The molding station S1 is a place where the molding cavity C (FIG. 3) is filled with resin to mold a molded product. The molding station S1 includes a mold clamping device 6, an injection device 7, and a gate cut cylinder (descent means). 8 are provided. The mold clamping device 6 includes a center shaft 3 also serving as a tie bar and two tie bars 9,
The lowering die 10 is horizontally lowered by the mold-clamping cylinder 11 and the lowering die 10 is clamped to the lower mold 5 by clamping the upper mold 12. The injection device 7 is for injecting the resin into the molding cavities C through the gates g by bringing the nozzles 14 into contact with the lower mold 5 and the upper mold 12, and is capable of moving back and forth with respect to the rotary table 1. ing. The dies 5 and 12 are maintained in a closed state even after the ascending and descending lift plate 10 is lifted, as in the related art.

An ejector pin 16 for pushing out a molded product from the molding cavity C is attached to an ejector plate 17 in the lower mold 5. The upper mold 12 is provided with a gate pin 19 for closing the gate g and cutting the resin, attached to the upper and lower plates 20. The upper and lower plates 20 have a sufficiently large weight, and function as urging means for urging the gate pin 19 downward to keep the gate g closed.

The upper plate 12a of the upper mold 12 has a pair of locking rollers 22a, 22a projecting outward by a spring or the like.
A male fitting 22 having a male fitting (FIG. 4) is attached thereto, and female fittings 23 having locking concave portions 23a, 23a (only one of which is shown in FIG. 4) into which the locking rollers 22a, 22a are fitted are provided on the upper and lower plates 20. When the upper plate 20 is raised, the locking roller 22 of the male fitting 22 is
The upper and lower plates 20a and 22a are fitted into the locking recesses 23a and 23a of the female fitting 23 to lock the upper and lower plates 20, thereby preventing free fall. The male fitting 22 and the female fitting 23 constitute locking means.

The gate cut cylinder 8 is a lifting and lowering plate 1 for mold clamping.
0 is provided. The gate cut cylinder 8 releases the locking of the upper and lower plates 20 by the male metal fittings 22 and the female metal fittings 23, lowers the upper and lower plates 20, and closes the gate g with the gate pins 19.

The cooling station S2 is a place where the lower mold 5 and the upper mold which have been transferred from the molding station S1 are cooled as they are.

The unloading station S3 is where the molded product is removed from the molding cavities C of the dies 5, 12 transferred from the cooling station S2, and includes a mold opening device 25 (FIG. 2). An ejector cylinder (not shown), a lifting device 27 and a fall prevention cylinder 28 are provided.

The mold opening device 25 raises and lowers the mold opening and lowering plate 31 to which the upper mold 12 is fixed by the four clamps 30 along the four guide bars 33 with the mold opening cylinder 32. Things. In addition, the lifting device (lifting means) 27
The claw 35 (FIG. 5) is hooked on the edge of the upper and lower plates 20 to raise the upper and lower plates 20 together with the gate pins 19, and the male fitting 22
The metal fitting 23 is fitted into the mold opening / lowering plate 31.
Are provided as a pair. The claw 35 is moved up and down by the lifting device 27, is turned horizontally, and is hooked on the edge of the upper and lower plates 20.

The fall prevention cylinder 28 is provided with a hole 37 of a fall prevention rod 37 (FIG. 2) provided on the mold opening / lowering plate 31.
A rod is inserted into a to prevent free fall of the mold opening / lowering plate 31, and is provided on an end plate 38 fixed to an upper portion of the guide bar 33. The ejector cylinder (not shown) pushes up the ejector plate 17 and removes the molded product from the molding cavity C by the ejector pins 16.

The mold exchanging station S4 is a place where the molds 5, 12 transferred from the unloading station S3 are removed from the rotary table 1 and exchanged for another mold. This station S4 is an unloading station S3
When the insert fitting is inserted in step (1), it is also used as a preheating station.

Next, the operation of the gate opening / closing device in the rotary injection molding machine according to the present invention having the above-described configuration will be described together with the gate opening / closing method. When the dies 5 and 12 are sent from the station S4 to the molding station S1 by rotation of the rotary table 1 and stop at a predetermined position,
The mold clamping device 6 is actuated to lower the mold lifting elevator 10 to clamp the dies 5 and 12, and the injection device 7 moves forward to apply the nozzle 14 to the clamped dies 5 and 12. Contact
The resin is injected into the molding cavity C.

When the injection of the resin is completed, the gate cut cylinder 8 is extended, and the upper and lower plates 20 which have been held up by the metal fittings 22 and 23 are lowered to close the gate g with the gate pin 19 and cut the resin. I do. Gate pin 19
When the gate g is closed, the injection device 7 supplies (measures) the next resin and retreats, and the mold clamping cylinder 11 contracts to raise the mold clamping lift plate 10.

The gate cut cylinder 8 having extended and lowered the upper and lower plates 20 is reduced by this time so that the dies 5, 12 can be transferred to the next station S2. But,
Even if the gate cut cylinder 8 shrinks, the upper and lower plates 20 push the gate pin 19 downward by its own weight, so that the gate pin 19 does not rise due to resin pressure or the like and does not open the gate g.

When the injection device 7 retreats and separates the nozzle 14 from the dies 5 and 12, and the lifting / lowering platen 10 is lifted and separated from the upper die 12, the next operation is prepared and the rotary table is prepared. 1 rotates, forming station S1
In step (1), the molds 5 and 12 are transferred to the next station S2 in a state where the resin injected into the molding cavity C is not completely cured.

For this reason, in the rotary injection molding machine provided with the gate opening / closing device according to the present invention, the rotary table 1 is rotated by 90 degrees as shown in FIG.
Compared to the conventional rotary injection molding machine that took 45 seconds,
As shown in FIG. 7A, the 90-degree rotation operation time of the rotary table 1 can be set to 80 seconds, and the effect of reducing the cycle time by 65 seconds is obtained.

At the molding station S1, the molding cavity C
The molds 5 and 12 filled with resin in the station S2
Is transferred to the unloading station S3.

When the dies 5 and 12 are transferred to the unloading station S3 and stopped at a predetermined position, the mold opening cylinder 32 is reduced and the mold opening / lowering board 31 is lowered. When the lift board 31 descends on the upper mold 12, the clamp 30 operates to fix the upper mold 12 to the mold opening lift board 31. Next, the mold opening cylinder 32 is extended to raise the upper mold 12 together with the mold opening and lowering platen 31. When the upper mold 12 has finished ascending,
The fall prevention cylinder 28 extends to move the rod to the fall prevention rod 3
7 to prevent free fall of the mold opening elevator 31.

The ejector cylinder 16 is actuated with the above-mentioned mold opened to raise the ejector pin 16, and the molded product in the molding cavity C is pushed out of the lower mold 5. When this is completed, the fall prevention cylinder 28 is reduced and the rod is pulled out from the hole 37a of the fall prevention rod 37, and then the mold opening cylinder 32 is reduced and the upper mold 12 is lowered onto the lower mold 5. Up to this time, the lifting device 27 has been operated to raise the upper and lower plates 20 together with the gate pins 19 and locked by the fittings 22 and 23.

In this manner, the dies 5 and 12 whose molded products have been taken out at the take-out station S3 and the upper and lower plates 20 have been locked in the raised state are rotated through the rotary table 1 via the station S4 to form the molding station S1. Is transferred to Hereinafter, the above operation is repeated.

In the present invention, the detailed structure and the number of stations such as the mold clamping device 6 and the mold opening device 25, which are the main parts of the rotary injection molding machine, are not limited to the embodiment shown in the figure, but are arbitrary. The lifting means 27 and the locking means 22 and 2
3 can be variously changed, for example, locking means 22 and 23
Can use a magnet. Further, in the embodiment, the downward urging force of the gate pin 19 utilizes the own weight of the upper and lower plates 20, but a spring may be used in combination with the upper and lower plates 20 or may be used alone.

[0034]

As described above, the gate opening and closing device in the rotary injection molding machine according to the present invention is a rotary table of a rotary table which is rotatable intermittently at a predetermined angle in the circumferential direction about the central axis. At the two rotation stop positions, the upper mold having a gate pin for closing the gate is vertically clamped to the lower mold on the rotary table with a mold lifting elevator, and the injection device nozzle is inserted into the molding cavities of both molds. There is a molding station that injects resin from the mold and a take-out station that secures the upper mold to the mold opening and lowering plate with a clamp, lifts it, separates it from the lower mold, and removes molded products from the molding cavities of both molds. In the rotary injection molding machine, the gate pin is provided with locking means for locking the gate pin which has been lifted to open the gate, and the locking means at the molding station. Lowering means for unlocking the gate pin and lowering the gate pin to close the gate, urging means for urging the gate pin downward to keep the gate closed, and raising the gate pin to open the gate Since the structure is provided with the lifting means for locking by the locking means, the mold can be transferred to the next station without waiting for the resin in the molding cavity to harden.

The lowering means is provided on the lifting / lowering board for mold clamping, the raising means is provided on the lifting / lowering board for opening the mold, respectively, and the gate pins are mounted on upper and lower plates which can be lowered by the lowering means and raised by the raising means. When the locking means is provided on the plate and the upper plate of the upper mold, the structure is rational and the structure can be simplified. Further, if the biasing means is configured to use the weight of the upper and lower plates, the structure is further simplified.

Further, the method for opening and closing a gate in a rotary injection molding machine according to the present invention is characterized in that, in a rotary injection molding machine provided with the gate opening and closing device having the above-described configuration, the gate is opened and closed until the injection of the resin into the molding cavity is completed. Lower the gate pin locked by the means to close the gate,
Since the rotary table is rotated in a state where the resin in the molding cavity is not completely cured while the gate is kept closed by the urging means and the two dies are transferred to the next station, the cycle is performed. Time can be shortened and production efficiency can be increased.

In a configuration in which the gate pin is raised by the lifting means at the removal station and locked by the locking means, and then the rotary table is rotated to transfer both molds to the molding station, the metal at the removal station is As a part of the mold operation, the gate pin can be locked by the locking means, so that the structure can be simplified and the cycle time can be reduced as compared with the case where the gate pin is raised at a molding station or the like.

[Brief description of the drawings]

FIG. 1 is a partially broken plan view showing an example of a rotary injection molding machine provided with a gate opening / closing device according to the present invention.

FIG. 2 is a partially cutaway front view of the rotary injection molding machine of FIG.

FIG. 3 is a sectional view showing an embodiment of a gate opening / closing device in the rotary injection molding machine according to the present invention.

FIG. 4 is an external view showing an example of a locking means.

FIG. 5 is a front view showing an example of a lifting unit.

FIG. 6 is a plan view showing a relationship between a claw of a lifting unit and upper and lower plates.

FIG. 7 is a comparison diagram of a molding cycle of the gate opening / closing method according to the present invention (a) and a conventional gate opening / closing method (b).

FIG. 8 is a sectional view of a conventional gate opening / closing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary table 5 Lower die 7 Injection device 8 Gate cut cylinder (downward means) 10 Lifting plate for mold clamping 12 Upper die 12a Upper plate 14 Nozzle 19 Gate pin 20 Upper and lower plates (biasing means) 22 Male fitting (Locking means) 23) Female fitting (locking means) 27 Lifting device (raising means) 30 Clamp S1 Molding station S3 Extraction station C Molding cavity g Gate

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/74

Claims (7)

(57) [Claims] 1. An upper die having a gate pin for closing a gate which is vertically movable at two rotation stop positions of a rotary table which is rotatable intermittently at a predetermined angle in a circumferential direction about a central axis. A molding station that clamps the lower mold on the rotary table with a mold lifting elevator and injects resin from a nozzle of an injection device into the molding cavities of both molds;
In a rotary injection molding machine provided with an unloading station provided with an unloading station for fixing an upper mold to a mold-opening elevating plate with a clamp, lifting the mold upward, separating the mold from the lower mold, and removing molded products from the molding cavities of both molds. Locking means for locking the gate pin that has been lifted to open the gate, lowering means for unlocking the gate pin by the locking means at the molding station to lower the gate pin and close the gate, Rotary injection characterized in that biasing means for biasing downward to hold the gate closed and lifting means for lifting the gate pin to open the gate and locking by the locking means are provided. Gate opening and closing device in the molding machine. 2. A gate opening / closing device in a rotary injection molding machine according to claim 1, wherein the lowering means is provided on a lifting / lowering board for mold clamping. 3. The gate opening / closing device in a rotary injection molding machine according to claim 1, wherein the lifting means is provided on a lifting plate for opening the mold. 4. A gate pin is attached to upper and lower plates which are lowered by lowering means and raised by raising means, and locking means is provided on the upper and lower plates and the upper plate of the upper mold. 4. A gate opening and closing device in a rotary injection molding machine according to claim 1, 2 or 3. 5. An urging means comprising upper and lower plates for urging a gate pin downward by its own weight.
A gate opening and closing device in the rotary injection molding machine as described in the above. 6. A rotary injection molding machine provided with the gate opening / closing device according to claim 1, wherein the resin is locked by the locking means until the injection of the resin into the molding cavity is completed. Lower the gate pin to close the gate, and while holding the gate closed by the biasing means, rotate the rotary table while the resin in the molding cavity is not fully cured, and transfer both molds to the next station A gate opening and closing method in a rotary injection molding machine. 7. The method according to claim 7, wherein the gate pin is lifted by the lifting means at the removal station and locked by the locking means, and then the rotary table is rotated to transfer the two dies toward the molding station. 7. The gate opening and closing method in the rotary injection molding machine according to 6.