JP3295922B2 - Multi-cavity mold device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot runner type multi-cavity mold apparatus used for injection molding of a thermoplastic resin.

[0002]

2. Description of the Related Art For example, in injection molding of a thermoplastic resin, a plurality of products are molded by one mold apparatus. In this case, a plurality of product-shaped cavities are formed between the fixed mold and the movable mold that open and close with each other, and the resin is injected into each cavity by a runner from a sprue that is one resin injection port provided in the fixed mold. Distribute.

FIG. 4 shows an example of the arrangement of runners in a multi-cavity mold apparatus. The mold device has eight cavities, and the runner has two branches from the sprue 1.
A secondary runner 2, a secondary runner 3 that branches off from both ends of the primary runner 2, and tertiary runners 4a and 4b that branch off from both ends of the secondary runner 3, respectively.
These tertiary runners 4a and 4b communicate with the cavities 5a and 5b via a spear system or the like which is a heating hot tip system. From the sprue 1 to the cavity 5a,
The distance to 5b is equal for all cavities 5a, 5b. The tertiary runners 4a and 4b include a backward tertiary runner 4a folded back toward the primary runner 2 and a forward tertiary runner 4b directed to the opposite side.

By the way, in a multi-cavity mold apparatus,
When the resin is a thermoplastic resin having low viscosity such as ABS resin or polystyrene, the filling balance between the cavities 5a and 5b becomes a problem. However, in the conventional mold apparatus, the primary runner 2 and the secondary runners 3 and 3
When the next runners 4a and 4b are located on the same plane,
There is a tendency that overfilling occurs in the cavity 5a located further inside, and underfilling occurs in the cavity 5b located further outside. As a result, the molded product may have dimensional differences. This is particularly problematic for thin-walled products such as the outer case of a video cassette.

[0005] As means for eliminating the imbalance in the filling between the cavities 5a and 5b, there is a method for eliminating the
The temperature of the body of the spear system may be changed every 5a, 5b. As a result of the trial, for example, the inner cavity 5a
When the temperature was set at 250 to 270 ° C., it was found that the filling balance could be achieved by setting the temperature at the outer cavity 5b to be higher by 40 to 50 ° C. However, if the temperature control is changed for each of the cavities 5a and 5b, this temperature control becomes troublesome.

As another means for eliminating the imbalance in filling, there is a method of increasing the temperature of the resin itself to enhance the fluidity of the resin. For example, if the temperature of the body is 300 ~
If the temperature is set to 340 ° C., the filling balance can be considerably maintained without changing the temperature setting between the inner cavity 5a and the outer cavity 5b. However, increasing the resin temperature itself has many disadvantages.

On the other hand, depending on the arrangement of the runners,
Balancing the filling is also conventionally performed. Actually, as shown in FIG. 5, a step-like relay portion 6 orthogonal to both the primary runner 2 and the secondary runner 3 has been conventionally provided. By providing such a stepped relay portion 6, the filling balance can be obtained in each of the cavities 5a and 5b. In a mold apparatus provided with such a stepped relay section 6, the manifold 7 is conventionally divided into two stages as described in, for example, JP-A-5-24087. I have. That is, 1
Traverse manifold member 8 forming next runner 2
, The secondary runner 3 and the tertiary runner 4 are formed
The two main body manifold members 9 are fixed, and the stepped relay portion 6 is formed from the traverse manifold member 8 to the main body manifold member 9. Further, in the conventional manifold 7, a sheath heater 11 whose shape can be set relatively freely is buried and fixed in concave grooves 10 formed on both sides of the manifold members 8 and 9 for heating.

However, in the conventional mold apparatus shown in FIG.
Since the manifold 7 is divided into two stages, the entire thickness of the manifold 7 is increased, which leads to an increase in the size of the entire die apparatus. In addition, since the manifold 7 is formed of three members, the cost is increased and the manufacturing of the mold is disadvantageous. Further, since the sheathed heater 11 is buried on both sides of the manifold members 8 and 9, the thickness of the manifold 7 is further increased.

[0009]

As described above, the secondary runner branches from the leading end of the primary runner via the step-like junction, and the tertiary runner branches from the leading end of the secondary runner. In the mold apparatus, although the filling of each cavity can be balanced, in the past, since the manifold was divided into two stages, the size of the entire mold apparatus was increased, and there was a problem that the mold was disadvantageous in manufacturing the mold. there were. further,
Since the sheathed heater was embedded on both sides of the manifold member, there was a problem that the manifold became thicker.

[0010] The present invention is intended to solve such a problem, and it is possible to balance the filling of each cavity, to reduce the size, and to easily manufacture the multiple-cavity mold device at low cost. The purpose is to provide. Still another object of the present invention is to prevent a manifold from being thickened by incorporating a heater in a multiple mold apparatus.

[0011]

According to a first aspect of the present invention, there is provided a multi-cavity mold apparatus, wherein a plurality of cavities are opened and closed with each other and a plurality of cavities are formed therebetween when the mold is closed. A mold is provided, and the mold is provided with a manifold formed with a runner branching from one resin injection port to each of the cavities, and the runner branches from the resin injection port and is located on a first plane. A primary runner, a stepped relay portion bent from a tip end of the primary runner in a direction intersecting the first plane, and a second plane branched from the tip end of the stepped relay portion and parallel to the first plane. An upper secondary runner, and a tertiary runner branched from the tip of the secondary runner and positioned on the second plane. The primary runner, the step-like relay, the secondary runner, Next runner and one One of consisting member said is obtained by forming on the manifold.

According to a second aspect of the present invention, in the multi-cavity mold apparatus of the first aspect, the primary runner is provided on the first plane in the manifold so as to achieve the latter object. And a cartridge heater is provided on the second plane with the tertiary runner interposed therebetween.

[0013]

According to the first aspect of the present invention, a plurality of molds are closed at the time of molding to form a plurality of cavities between the molds, and a plurality of cavities are formed between the molds. The injected resin is branched by a runner and filled into each cavity. In the runner, the resin branches from the resin inlet to the primary runner, and then bends from the tip of the primary runner to the step-like junction, and then from the tip of the step-like junction to the secondary runner. The branch then branches from the tip of the secondary runner to the tertiary runner and goes to each cavity. Here, while the primary runner is on the first plane, the secondary runner and the tertiary runner are on a second plane different from the first plane, and the primary runner and the secondary runner are mutually connected via a step-like relay. By communicating, each cavity is evenly filled with resin. Said 1
The next runner, the stepped relay portion, the secondary runner, and the tertiary runner are formed in a single-piece manifold, and the thickness of the manifold can be reduced.

Further, in the multi-cavity mold apparatus according to the present invention, a cartridge heater positioned on the first plane with a primary runner interposed therebetween, and a cartridge heater positioned on the second plane with a tertiary runner interposed therebetween. The thermoplastic resin in the runner is heated by the cartridge heater and kept in a molten state.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the multi-cavity mold apparatus of the present invention will be described below with reference to FIGS. In FIG. 3, reference numeral 21 denotes a fixed mold and 22 denotes a movable mold. The fixed mold 21 and the movable mold 22, which are molds, move vertically in the figure to open and close, and when the mold is closed, a total of eight cavities 23 are interconnected. It is formed between them.

The fixed mold 21 is provided with a first fixed side receiving plate on the back side (upper surface in the drawing) of the fixed side mold plate 26 forming the cavity 23.
27 is fixed, and a second fixed-side receiving plate 28 is fixed to the back side of the first fixed-side receiving plate 27. Further, a fixed-side mounting plate 30 that is mounted on a fixed-side platen of the injection molding machine is fixed to the back side of the second fixed-side receiving plate 28 via a fixed-side spacer block 29. A manifold 31 made of one integral member is provided between the second fixed-side receiving plate 28 and the fixed-side mounting plate 30 at a position inside the fixed-side spacer block 29.
Has been fixed through. Further, one sprue bush 36 to which the nozzle of the injection molding machine is connected is fixed to the manifold 31 through the fixed-side mounting plate 30.
The inside of the sprue bush 36 is a sprue 37 serving as a resin injection port.

In the manifold 31, a runner is formed which branches from the sprue 37 to each of the eight cavities 23. As shown in FIGS. 1 and 2, this runner has a cylindrical 0th-order runner 38 coaxially communicating with a sprue 37 and a cylindrical primary 0th-order runner vertically bifurcated from the tip of the 0th-order runner 38. A runner 39, a cylindrical stepped relay portion 40 that bends vertically from both ends of the primary runner 39, and a cylindrical secondary runner that vertically branches into two from the tip end of the stepped relay portion 40, respectively.
41, and a columnar tertiary runner 42 that branches vertically from each end of the secondary runner 41. The distal ends of these tertiary runners 42 are bent vertically to form a second fixed part in the manifold 31. The outlet portion 43 has a cylindrical shape and extends to the surface on the side of the side receiving plate 28. The zero-order runner 38,
The step-like relay section 40 and the outlet section 43 have a direction parallel to the mold opening and closing directions of the fixed mold 21 and the movable mold 22. on the other hand,
The primary runner 39 is a first runner orthogonal to the mold opening / closing direction.
The secondary runner 41 and the tertiary runner 42 are located on the plane P1, and the secondary runner 41 and the tertiary runner 42 are on the first plane P2 which is also orthogonal to the mold opening / closing direction and located on the fixed side receiving plate 28 side of the first plane P1. positioned. Note that the outer shape of the manifold 31 conforms to the arrangement of the runners 38, 39, 41, and 42.
It has a concave portion 44 on both sides located between the secondary runners 41. The runners 38, 39, 41, and 42 including the stepped relay portion 40 and the outlet portion 43 are processed by a drill. Blocked by 47.

In the manifold 31, there is provided a linear upper cartridge heater 51 which is located on the first plane P1 and sandwiches the primary runner 39 in parallel. A linear lower cartridge heater 52 is disposed on two planes P2 and sandwiches each tertiary runner 42 in parallel. Each of the cartridge heaters 51 and 52 is inserted from the outer surface of the manifold 31 including the concave portion 44 into a hole formed by drilling. The upper cartridge heaters 51 are paired with the zero-order runner 38 interposed therebetween, and there are a total of four heaters. The lower cartridge heater 52 is located on the same second plane as P2
To avoid contact with the upper secondary runner 41,
There are also 16 pairs, with the next runner 41 in between.

The outlets 43 of the tertiary runner 42
Communicate with the cavities 23 via a spear system 56, respectively. The spear system 56 is
Bush 5 penetrating through 7 and 28 and fixed to manifold 31
7 and a body 58 built in the bush 57, and a heater is built in the body 58. The outlets 43 of the tertiary runner 42 are connected to the resin passage 59 and the gate 60 in the spear system 56, respectively.
Through each cavity 23. The path from the sprue 37 to each cavity 23 is all equal. At the tip of the body 58, there is a chip located near the gate 60, and this chip has a built-in heater different from the heater of the body 58.

The movable mold 22 has a movable-side receiving plate 67 fixed to the back (lower side in the figure) of a movable-side mold plate 66 which forms the cavity 23.
A movable mounting plate fixed to the movable platen of the injection molding machine is fixed to the back side of 67 via a movable spacer block. A protruding plate provided with a protruding pin 68 is movably provided between the movable receiving plate 67 and the movable mounting plate.

In actual use, FIGS. 1 and 3
Is the up-down direction.

Next, the operation of the above configuration will be described. At the time of molding, the fixed mold 21 and the movable mold 22 are closed, and a cavity 23 is formed between them. Then, a thermoplastic resin such as ABS resin or polystyrene melted into the sprue 37 from the nozzle of the injection molding machine. Inject This resin is distributed through a sprue 37, a zero-order runner 38, a primary runner 39, a step-like relay portion 40, a secondary runner 41 and a tertiary runner 42, and a resin passage 59 of a spear system 56 is provided from an outlet 43 thereof. The inside of each cavity 23 is filled from the gate 60 through the inside. And these cavities 23
After the resin filled in, that is, the product cools and solidifies,
The fixed mold 21 and the movable mold 22 are opened, and the product is released by the ejection pin 68 and taken out. Thereafter, the mold is closed again, and the above molding cycle is repeated.

The resin in the runners 38, 39, 41 and 42 is heated by the cartridge heaters 51 and 52 in the manifold 31, and the resin in the resin passage 44 is heated by the heater of the body 58 of the spear system 56. By being heated, these runners 38, 39, 41, 42 and resin passage 44
The resin within is always maintained in a molten state throughout the entire molding cycle. On the other hand, when filling the cavity 23 with resin, the heating of the chip of the spear system 56 causes the resin in the gate 60 to be in a molten state and the gate 60 to be in an open state, but otherwise, By cooling the chip of the spear system 56, the resin in the gate 60 is solidified and the gate 60 is closed.

As described above, the molten thermoplastic resin branches off from the zero-order runner 38 to the primary runner 39 in the manifold 31.
It bends from the tip of 39 to the step-like relay part 40, and then branches from the tip of this step-like relay part 40 to the secondary runner 41,
Next, the tip of the secondary runner 41 branches off to the tertiary runner 42 and goes to each cavity 23. Here, while the primary runner 39 is on the first plane P1, the secondary runner 41 and the tertiary runner 42 are on the second plane P1 different from the first plane P1, and the primary runner 39 and the secondary runner 41 By communicating with each other via the step-like relay section 40 orthogonal to these, the respective cavities 23 are uniformly filled with resin. In this way, the temperature of the resin can be raised,
The resin filling of each cavity 23 can be balanced without changing the temperature control or the runner diameter every time. Therefore, a product of stable quality having no difference in dimensions and the like can be obtained.

Further, since all the runners 38, 39, 41 and 42 including the step-like relay portion 40 and the outlet portion 43 are formed in the manifold 31 formed of one integral member, the thickness of the manifold 31 can be reduced. Therefore, the whole mold apparatus can be downsized. At the same time, as compared with the case where the manifold is configured by being divided into a plurality of members, it is more advantageous in manufacturing the mold, and can reduce the cost and facilitate the manufacture of the mold.

Further, an upper cartridge heater 51 is provided in the manifold 31 so as to sandwich the primary runner 39 on the first plane P1 and to be located in a manner sandwiching the tertiary runner 42 on the second plane P2. Since the lower cartridge heater 52 is provided, it is possible to prevent the manifold 31 from being thickened by incorporating the heaters 51 and 52 while effectively performing the heating. In this way, the manifold 31 can be made thinner, and the entire mold apparatus can be made smaller.

The present invention is not limited to the above-described embodiment, and various modifications can be made. For example,
Although the mold apparatus of the above-described embodiment has eight cavities, the number of cavities is not limited to eight. Further, in the above embodiment, the hot runner mold apparatus for opening and closing the gate by the spear system has been described as an example, but the present invention provides a valve gate type hot runner mold apparatus for mechanically opening and closing the gate, or And other hot runner mold devices.

[0028]

According to the first aspect of the present invention, the runner is
A primary runner located on the first plane branches off from the resin inlet, and a step-shaped relay portion is bent from a tip end of the primary runner in a direction intersecting with the first plane. , A secondary runner located on a second plane parallel to the first plane branches off, and a tertiary runner located on the second plane branches off from the tip of the secondary runner. Filling balance can be maintained, and since the primary runner, the step-like relay portion, the secondary runner, and the tertiary runner are formed in a single-piece manifold, the entire manifold can be thinned. The entire mold apparatus can be reduced in size, and the mold can be easily manufactured at low cost.

Further, according to the second aspect of the present invention, a cartridge heater is provided in the manifold so as to sandwich the primary runner on the first plane, and the tertiary runner is sandwiched on the second plane. Since the cartridge heater is provided at the position, the manifold can be prevented from being thickened by incorporating the heater while heating is effectively performed, and the manifold can be made thinner, and the entire mold apparatus can be made smaller.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a manifold showing one embodiment of a multi-cavity mold apparatus of the present invention.

FIG. 2 is an explanatory perspective view of a part of the manifold.

FIG. 3 is a vertical cross-sectional view of the fixed mold side.

FIG. 4 is an explanatory front view of an arrangement of runners showing an example of a conventional multi-cavity mold device.

FIG. 5 is a longitudinal sectional view of a manifold showing another example of a conventional multi-cavity mold device.

[Explanation of symbols]

21 Fixed mold (mold) 22 Movable mold (mold) 23 Cavity 31 Manifold 37 Sprue (resin injection port) 39 Primary runner 40 Stepped junction 41 Secondary runner 42 Tertiary runner 51 Upper cartridge heater (cartridge heater) 52 Lower cartridge heater (cartridge heater) P1 First plane P2 Second plane

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/26-45/30 B29C 45/72-45/73 B29C 33/00-33/08

Claims (2)

(57) [Claims] 1. A mold comprising a plurality of molds which open and close with each other and form a plurality of cavities therebetween when the mold is closed.
A manifold formed with a runner branching from one resin inlet to each of the cavities, wherein the runner branches from the resin inlet and is located on a first plane.
A second runner and the first runner
A step-shaped relay portion bent in a direction intersecting with the plane, and a second portion branched from a tip end portion of the step-shaped relay portion and parallel to the first plane.
A secondary runner located on a plane, and a tertiary runner branched from the tip of the secondary runner and located on the second plane. The primary runner, the step-like relay section, the secondary runner, A multi-cavity mold apparatus, wherein a tertiary runner is formed in the manifold made of a single member. 2. A cartridge heater is provided in the manifold with the primary runner interposed on the first plane and a cartridge heater is arranged on the second plane with the tertiary runner interposed therebetween. The multi-cavity mold apparatus according to claim 1, further comprising: