JPS61177219A - Core gate and core revolving type injection molding tool - Google Patents

Abstract

PURPOSE:To enable to shorten the molding time by a structure wherein a cooling water circulating circuit is formed in a mold so as to circulate cooling water in order to effectively cool the heated mold. CONSTITUTION:A spool bushing fitting hole 8 is pierced at the center in the interior of a revolving core 4. A hole 5 for a spool and a gate 6 are bored at the center in the interior of a cylindrical body 9. A spool bushing 11, in the wall part lying between the hole 5 for the spool and the outer peripheral surface ranging from the upper part of said cylindrical body 9 to the lower part of which water circulating holes 10 are properly formed, is fitted in the fitting hole 8 of the revolving core 4 and fixedly installed to the plate side of a molding tool. In addition, the water circulating holes 10 at the lower part of the spool bushing 11 are communicated with water circulating passages 13 on the plate side of the molding tool. Concretely, cooling water flows from the water circulating passage 13 on one side, passes through the water circulating hole 10 in the bushing 11, enters the fitting hole 8, passes through the water circulating hole 10 on the other side in the bushing 11 and finally escapes through the water circulating passage 13 on the other side so as to circulate at al times during the molding action of the mold. Accordingly, the bushing 11 and the revolving core 4 are cooled as a whole, resulting on cooling and hardening the resin injected between a cavity 3 and a core part 4a from the hole 5 for the spool effectively in a short time.

Description

[Detailed description of the invention] I)...Industrial application field and prior art (1)...
The present invention relates to the improvement of a so-called core-gate-core rotary injection mold, in which a cooling water circulation circuit for mold cooling is formed in the mold, and the cooling water is passed through and heated as injection molding continues. By effectively cooling the mold, it is possible to shorten the molding time (time required per shot) (to about the same level as conventional methods).
This enabled a significant improvement in production efficiency.

A core gate type mold is a mold that has a configuration different from a cavity pin gate type mold, and has a gate on the core side (not the cavity side), and the cavity pin gate has a gate on the surface side of the molded product. While there are gate marks,
Core gates leave gate marks on the inside of the molded product, so
It is mainly used for molding products that require a particularly beautiful exterior appearance, such as cosmetic lids.

In addition, when molding a molded product with a threaded structure inside the molded product, such as the cosmetic lid mentioned above, the core rotating type is used to remove the molded product from the core after molding, while rotating the core. Since the core is opened, the core is configured to rotate by the rotation of a gear attached to the lower end of the core.

(2)...The conventional core-gate-core rotary injection mold (see Figure 4) does not have a cooling water circulation structure as in the present invention, so if the molding operation continues, the resin will be injected. It gradually heats up due to the heat of melting the plastic.

Conventionally, especially in core-gate-core rotary molds, it was considered impossible to cool the mold by passing cooling water around it because the core is rotary. The above heat was left to heat absorption by the mold and natural heat radiation.

As molding continues, the temperature of the entire mold tends to rise, especially around the cavity, core, and spool hole, and when this happens, the injected molten resin does not cool down quickly and its hardening is delayed. The one-cycle time (time per shot) required to open the mold and take out the molded product becomes longer, which naturally reduces production efficiency.

This is completely contrary to the original purpose of increasing production by shortening the time per shot as much as possible.

(3)...(Then, there are two viewpoints for improving efficiency using injection molds.)

For example, if you are currently molding a total of 8,000 pieces using two 4-cavity molds (two molding machines) with a total of 1,000 shots in 12-hour operation, 1)...the time per shot is... If the time could be shortened, a total of 16,000 pieces could be molded with a total of 2,000 shots in 12 hours. In other words, the production quantity can be doubled.

11) If it were possible to produce a total of 8,000 pieces in 12 hours as before, only one mold (molding machine) would be required.

This is a huge hassle for molders.

That is, the present invention greatly shortens the time per shot by providing a cooling structure in the mold, thereby making it possible to achieve the above-mentioned efficiency improvement and labor-saving results.

■)...Structure of the present invention Next, the structure of the present invention will be explained with reference to the illustrated embodiment. and a rotating core q on the stationary side template l.
In other words, a core part 14a for internal thread forming is formed at the upper end, a spool hole is bored in the center of the inside, and a core part I/-a is formed from the tip of the spool hole S. In a core gate core rotary injection mold of an existing configuration, in which a core ψ is fitted so as to be rotatable as appropriate by rotating a gear 7 attached to the lower end thereof by an appropriate means, the inside of the rotating core t is A spool bushing fitting hole is provided in the center, a spool hole S and a gate 6 are bored in the center of the cylindrical body 9, and the outer circumferential surface from the top to the bottom of the cylindrical body 9 is cut. A spool bushing l/ having a water passage hole IO suitably formed in the thick part between the spool holes S is fitted and fixed into the spool bushing fitting hole of the rotating core t, and the spool bushing: The water passage hole 10 in the lower part of Lll is configured to communicate with the water passage 13 on the plate side (for example, plate ld).

In the above, the movable side mold plate 1 is made of, for example, one plate with a cavity 3 formed on the bottom surface, and the fixed side mold plate l is made of, for example, plates) /a, /b, /c,
/d, a rotating core t is rotatably fitted across plates /a-/c, and the rotating core t is rotated as appropriate.
It is provided so that it rotates by transmitting rotation from the driving gear 2, etc.

The spool bush ll is fitted into a spool bush fitting hole g provided in the rotating core q, for example, so that the upper surface of the gate 6 at its tip is flush with the core part ψa surface, and the lower end is aligned in advance. The water passage hole IO and the water passage 13 are connected to the plate ld in which the water passage /3 is bored and fixedly installed (does not rotate).

For example, the water passage hole IO at the tip of the spool 19 can be made by forming the cylindrical body 9 with a small diameter and cutting a groove 10a in the outer circumferential surface of the cylindrical body 9, as shown in the second figure. , a pipe 9a is fitted over the cylindrical body 9 to form a water passage hole IO.

The grooves 10a may be linear as shown, or may be spiral or zigzag (both not shown).

(11) As shown in the third figure, it is formed by directly drilling into the thick part between the outer peripheral surface of the cylindrical body 9 and the spool hole S.

In addition, in the figure, ! ttzl tsld spool bush/
/A is a runner plate, 17.1g
19 is a template mounting plate, 19 is a spool (resin), 20 is a molded product 1, and 2/ is a runner pin.

m)... Effect (1)... Cooling water passes from the water passage 13 of the play)/d through the water hole lO of the tip l/ of the spool 19, enters the spool bush fitting hole, and enters the other side. It passes through the water passage hole 10 and exits to the water passage 13 on the other side, and constantly circulates during the molding operation of the mold.

As a result, the entire spool bush l/ and rotating core are cooled, that is, from the spool hole S to the cavity 3.
The resin injected between the core portion Ua and the core portion Ua is effectively cooled and hardened in an extremely short period of time.

(2)...Removal of the molded product after hardening is performed in the following order.

(1)...Runner plate/6 and play 1-/d
The gap 1 is opened, and the tip of the spool 19 (portion of the gate 6) supported by the runner pins 2 and 7 is separated from the inside of the molded product 20.

(11)...The movable template Ω separates from the plate/a, and the molded product 20 emerges from the cavity 3.

(Ill)...When the rotating core t/- rotates\ and the space between the plates lb and /c opens, the core part ψa becomes the molded product, 20
The molded product KO0 is removed by rotation from the threaded portion of the molded product KO0.

(1v)...Meanwhile, the space between the runner play)/A and the template mounting plate 1g opens, and the spool 19 comes off the runner pin J/tip and is taken out.

(V)...The entire mold closes again and returns to its original state.

■)...Effect As mentioned above, it is clear that shortening the time per shot in injection molding has a significant relationship in terms of improving production efficiency and saving labor. Conventionally, no effective cooling means existed.

Therefore, in the present invention, a spool bush (which does not rotate) is inserted into the rotating core that rotates once.

A circulating cooling channel is formed inside the spool bushing and through the spool pocket fitting hole of the rotating core to effectively cool the rotating core and other parts. The spool bushing closest to the water hole is effectively cooled, reducing the curing time of the spool portion of the injected resin.

If the spool does not harden and breaks into pieces when the mold is opened, the molded product will not be able to be removed. Conventionally, the mold was opened using the spool's hardening time as a guide. However, according to the present invention, the spool can be cooled and hardened as quickly as possible.

(2)...In addition, the entire rotating core is cooled, and the cooling water is circulated especially in the upper part of the spool bushing fitting hole, so the core is cooled and the molded product is shortened. Now it can be cooled and hardened over time.

(3) - The cooling heat of the cooled rotating core is conducted to other parts of the mold and the entire mold is cooled, so the mold will not gradually heat up as injection molding continues. The temperature of the entire mold can be maintained at an average low temperature at all times, and molding can be continued at a high rate under stable conditions.
A homogeneous molded product can be obtained.

(4)...As mentioned above, since the mold can be effectively cooled, the mold time can be reduced to about 7 times compared to the conventional method (e.g., the conventional method,
One shot takes 40 seconds → in the present invention, one shot takes about 20 seconds), and can be highly effective in improving production efficiency and saving labor.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of a core-gate core rotary injection mold according to the present invention, Fig. 2 is a vertical sectional view of an embodiment of a spool bushing, and (b) 3 is a partially cutaway front view and a plan view of another embodiment of the spool bush, and FIG. 4 is a sectional view of a conventional core gate core rotary mold. . Number, l... fixed side template, / a = / d... plate constituting the fixed side template, yu... movable side template, 3...
・Cavity, t... Rotating core, ψa... Core part, s
... Spool hole, 6... Gate, Su... Spool bush fitting hole, 9... Cylindrical body, 9a... Pipe,
10...Water hole, 10a...Groove, //...Spool bush, lsu...Gear, 13...Water passage, lti
, t s...oil seal, 16...runner plate, 17, Ig...template mounting plate, 19...° spool 1.20...molded product, U/...runner pin.

Claims (1)

[Claims] (1) A fixed side template and a movable side template are installed opposite each other, an arbitrary cavity is provided in the movable side template, and a rotating core is attached to the fixed side template, that is, a core part for internal thread forming is attached to the upper end. A rotary core is formed in which a spool hole is bored in the center of the interior, and a gate is bored from the tip of the spool hole to the core portion, and the rotary core can be freely rotated as appropriate by rotating a gear attached to the lower end of the rotating core by an appropriate means. In a core/gate core rotary injection mold with an existing configuration, a spool bushing fitting hole is provided in the center of the rotating core, and a spool hole and a gate are provided in the center of the cylindrical body. drilled,
Further, a spool bush having a water passage hole suitably formed in the thick part of the cylindrical body is fitted and fixed into the spool bush fitting hole of the rotating core, and the water passage hole in the lower part of the spool bush is connected to the plate side. A rotary injection mold with a core-gate core that communicates with a water passageway.