JPS6366654B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for an injection molding machine, and particularly to a hot runner for a mold that performs molding of multiple molds using a large-sized machine.

Recently, in order to improve productivity, there has been a tendency to use large-sized machines to use multi-cavity molds that mold multiple products in a single injection molding process. When performing multi-cavity molding using a large machine, conventional methods have been to install a runner on the dividing surface of the mold or a hot runner inside the mold, but the former method requires a complicated and expensive mold. However, since the latter also serves as a hot runner, a heating device for heating the runner portion must be provided in the mold, further making the mold complex and expensive.

Therefore, there is a method in which a groove is provided in the fixed plate, a hot runner is placed in the groove, and the hot runner is replaced so that material can be injected from any arbitrary point on the same plate into multiple molds on the plate depending on the mold. Although this method requires a complicated structure for the fixed plate, it has the advantage that the hot runner can be changed to match the mold, and the mold has a simple structure.

However, the hot runner in this fixed plate also extends in the axial direction due to thermal expansion, and when material is injected into the mold, it protrudes from the mold mounting surface of the fixed plate and touches the nozzle to the gate of the mold. It is necessary to consider two conditions: the mold must be in a concave state than the mounting surface.

The present invention is to provide a hot runner in a fixed plate that satisfies the two conditions mentioned above.

Next, one embodiment of the present invention will be described with reference to FIGS. 1 to 7. Reference numeral 11 is an injection device that supplies molten material into a mold (not shown). Reference numeral 12 denotes a fixing plate in which grooves 13 and 14 are provided. Reference numeral 15 denotes a hot runner (1), which is provided with a heater 16 on its outer peripheral surface to heat the molten resin passing through the runner 17 inside. The hot runner (1) 15 has one end supported by a hot runner block 18 fixed to the fixed plate 12, and the other end supported by a material branching support block 19, as shown in FIG. 18 so as to be slidable by l dimension. Therefore, runner 17
The inside can absorb thermal expansion due to the passage of molten material or due to heating. The hot runner block 18 distributes the molten material supplied from the injection device 11 to the hot runners (1) 15 within a plurality of fixed plates using switching valves 18a and the like. Reference numeral 20 denotes a hot runner (2), which is supported at both ends by the support block 19 and nozzle mounting block 21, and is adapted to heat the molten material passing through the internal runner 23 by a heater 22 provided on the outer peripheral surface. The support block 19 is fitted so as to maintain a slight gap from the groove width W of the groove 13 of the fixing plate, and is fitted in the lateral direction in FIG.
It is now possible to move inside. The nozzle mounting block 21 is fitted with the groove width L of the groove 14 while maintaining a slight gap, and is movable in the vertical direction in the figure, that is, within the groove 14, so that the hot runner ( 2) Even if 20 is stretched due to thermal expansion, it can be handled. Further, the nozzle mounting block 21 is attached with a nozzle 25 that touches the mold 24 shown by the chain line in FIG. 3 during injection, and the fixed plate 1
It is operated by an eccentric cam 26 so as to be recessed from the mold mounting surface A of No. 3.
27 is a hydraulic cylinder that controls the drive of the eccentric cam 26, and as shown in FIGS. 4 to 6, a rack 29 connected to the piston rod 28 of the hydraulic cylinder 27 meshes with a gear 31 attached to a shaft 30. A gear 33 attached to a shaft 32 meshing with the same gear 31
is driven to rotate the shafts 30 and 32 in the direction of arrow a shown in FIG. 6, thereby driving the eccentric cams 26 attached to the shafts 30 and 32, respectively.

The shafts 30 and 32 extend from the sides B and C of the fixed plate 12 to the groove 14 as shown in FIG.
The inside extends to the lower part of the support block 19 and the nozzle mounting block 21, respectively, and when the support block 19 and the nozzle mounting block 21 are injected, the support block 19 and the nozzle mounting block 21 can be moved forward and backward with respect to the mold at the same time. An eccentric cam 26 is attached to allow the rotation. Therefore, at the time of injection, the runner support block 19 is lifted upward in the drawing by a predetermined distance S by the eccentric cam 26, so that the hot runner (1) 15 is moved from the hot runner block 18 side toward the support block 19 as shown in FIG. As a result, the hot runner (1) 15 rotates by a predetermined angle θ using the hot runner block 18 as a fulcrum, so that the hot runner block 18 rotatably supports the rotating shaft 35 by the bearing 34. do.

In the above-mentioned embodiment, the hot runner (2) was provided in front of the hot runner (1) via a support block for material distribution, but of course the hot runner (1) alone may be used, and the hot runner can be divided into multiple pieces depending on the mold. In addition, the eccentric cam can be driven not only by hydraulic pressure but also by air pressure or other liquid or gas pressure.

With the configuration as described above, problems such as axial elongation due to thermal expansion and nozzle touching of the injection nozzle to the mold during injection can be solved.

[Brief explanation of drawings]

Fig. 1 is a plan view showing one embodiment of the present invention, Fig. 2 is a plan view showing one embodiment of the present invention;
The figure is a cross-sectional view of Fig. 1, Fig. 3 is a cross-sectional view of Fig. 1, and Fig. 4 is a cross-sectional view of Fig. 3.
The figure is an explanatory diagram of the eccentric cam drive, FIG. 5 is a Z-obscured view in FIG. 4, and FIG.
Figure 7 is a side view of the hot runner (1) showing the state at the time of injection. 11...Injection device, 12...Fixing plate, 1
3, 14... Groove, 15... Hot runner (1), 18
... Hot runner block, 19 ... Support block, 20 ... Hot runner (2), 21 ... Nozzle mounting block, 25 ... Injection nozzle, 26 ... Eccentric cam, 27 ... Hydraulic cylinder, 27 ... Rack,
30, 32... shaft, 31, 33... gear.

Claims (1)

[Scope of Claims] 1. A groove is provided in a fixed plate for mounting a fixed mold, which is opposite to a movable plate for mounting a movable mold, and one end of the injection nozzle of an injection device for supplying material comes into contact with the groove, and melts the material. It is supported by a hot runner block fixed to a fixed plate that distributes the material, and the other end is fitted so as to be movable within the groove with a slight gap to the width of the groove, and faces the mold gate. a hot runner supported on a nozzle mounting block having a nozzle for injecting molten material into the mold on a surface thereof, the material injection nozzle being a gear mounted on a piston rod fitted in a hydraulic or pneumatic cylinder;
The nozzle mounting block at the other end of the hot runner is arranged so that the eccentric cam attached to the shaft meshing with the gear is convex from the mold mounting surface of the fixed plate during injection, and concave from the mold mounting surface at times other than injection. A hot runner for an injection molding machine, characterized in that the fixed plate is moved forward and backward relative to a mold mounting surface, and the hot block at one end of the hot runner and the hot runner are slidably attached in the axial direction of the hot runner. 2. The injection molding according to claim 1, wherein the nozzle mounting block is attached to the terminal end of a hot runner branched into at least two parts via a support block for material branching provided midway. Machine hot runner. 3. In the hot runner according to claims 1 and 2, when the injection nozzle comes into contact with the mold gate during injection, the hot runner moves toward the mold side by a predetermined angle using the hot runner block at one end as a fulcrum. A hot runner for an injection molding machine that is characterized by rotating.