JPH0313311A - Hot runner for molding resin - Google Patents

Abstract

PURPOSE:To contrive to simplify or lighten the structure of a hot runner by constituting a part of the hot runner with the flexible pipe absorbing the elongation due to thermal expansion in longitudinal direction by bending. CONSTITUTION:A hot runner 6 is composed of the flexible pipes 13, 13 connecting a nozzle joint 11 to each gate joint 12. In said hot runner, when it is heated upon molding of resin, the pipe 13 is elongated in longitudinal direction due to the thermal expansion while the elongation starts from the nozzle joint 11. Then, while the gate joint 12 receives the force due to the elongation from the pipe 13, said joint 2 turns in the state where its outlet 17 is lapped on a feeding hole 5a with said hole 5a of the gate 5 as the center by sliding convex spherical contact surface 12a on the concave contact surface 4a of a gate member 4. Consequently, said pipe 13 is bent smoothly.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a hot runner for resin molding equipment.

(Prior art) In resin molding equipment, a hot runner type is generally used, which does not cool the runner installed between the nozzle and the gate in each cycle, but separates and cools only the molded product side from the gate and takes it out. Are known.

An example of the structure of the hot runner is shown in Figures 11 to 13.
As shown in the figure. That is, this hot runner a is made by drilling a thick iron plate to form a resin material passage f having an inlet connected to a nozzle and an outlet e connected to a gate d of a mold C. This is what I did. In this case, the hot runner a has the inlet port fixed to the support plate g, and a sliding part between the mold C and the support plate g to allow elongation due to thermal expansion. The outlet e is held by a holding member, and the outlet e which does not match the inlet i of the gate d during cooling as shown in FIG. It is configured.

(Problem to be Solved by the Invention) Therefore, in the case of the above-mentioned conventional hot runner, the elongation due to thermal expansion is allowed by the slide mechanism, so that the outlet is aligned with the gate without positional deviation during thermal expansion. In order to achieve this, the hot runner is required to have high dimensional accuracy by calculating the amount of thermal expansion. Moreover, this hot runner requires the above-mentioned slide mechanism, and furthermore, it is necessary to make a hole in the iron plate to form a resin material passage.
As the number of gates increases, the processing becomes more difficult and the hot runner itself becomes heavier.

These problems become more pronounced as the hot runner becomes larger, and furthermore, hot runners are usually expensive due to the above-mentioned requirements for high dimensional accuracy and difficulty in processing. It is.

That is, an object of the present invention is to allow a hot runner to elongate due to thermal expansion with a simple structure without the above-mentioned problems.

(Means for Solving the Problems) In order to solve such problems, the present invention absorbs the elongation due to thermal expansion of the hot runner by curving the hot runner itself, and improves the flow rate between the hot runner outlet and the gate. This prevents the injection port from being misaligned due to the thermal expansion.

That is, the means according to claim (1) for this purpose is a hot runner which constitutes a flow path for sending the resin material received from the molding machine to the gate of the mold, and which is connected to the discharge port of the molding machine. It has an inlet for resin material connected to the inlet of the gate, and an outlet for resin material connected to the inlet of the gate, and is composed of a flexible pipe that absorbs longitudinal elongation due to thermal expansion by curving. It is characterized by the presence of

The means according to claim (2) is the hot runner according to claim (1), wherein the end on the inlet side is fixed at a fixed position with respect to the mold, and the contact surface with the gate is , is characterized in that it is formed into an arcuate surface so as to rotate around the injection port position of the gate due to the longitudinal elongation due to thermal expansion of the pipe.

The means according to claim (3) is characterized in that the hot runner according to claim (1) or (2) is pressed against the gate by a spring.

(Function) In the hot runner according to claim (1), elongation in the longitudinal direction due to thermal expansion is absorbed by curving.

In the hot runner according to claim (2), the gate connecting portion and the gate are in contact with each other on an arcuate surface, and when the pipe extends in the longitudinal direction due to thermal expansion, the gate connecting portion is removed from the pipe due to this elongation. The force causes the gate to rotate about the inlet position, thereby causing the pipe to curve.

In other words, the elongation due to thermal expansion of the pipe is absorbed by the rotation of the gate connection and the curvature of the pipe, and the position of the outlet of the gate connection and the position of the inlet of the gate are substantially different before and after thermal expansion. remains unchanged.

In the hot runner according to claim (3), since the gate connecting portion is pressed against the gate by the spring,
While allowing rotation of the gate connecting portion, the gate connecting portion can be pressed against the gate against the pressure of the resin material without causing resin leakage.

(Effects of the Invention) Therefore, according to the invention set forth in claim (1), a part of the hot runner is made up of a pipe, and this pipe is bent when it thermally expands. Substantial fluctuations in the position of the gate connection part before and after thermal expansion can be prevented, and therefore, high dimensional accuracy is not required for the hot runner itself, and there is no need for a conventional sliding mechanism, and the pipe can be removed easily. Because it can be used
The structure of the hot runner can be simplified or lightened,
Furthermore, the hot runner can be manufactured easily and its manufacturing cost can be reduced.

According to the invention set forth in claim (2), the gate connecting portion is brought into contact with the gate on an arcuate surface, and when the pipe expands thermally, the gate connecting portion is rotated around the injection port position of the gate to curve the pipe. Therefore, while ensuring sealing between the gate connection part and the gate, the rotation of the gate connection part allows the pipe to curve smoothly without causing excessive deformation, and prevents local stress concentration on the pipe. Therefore, its durability can be improved.

In the hot runner according to claim (3), since the gate connecting portion is pressed against the gate by a spring, leakage of the resin material can be prevented while allowing rotation of the gate connecting portion. can.

(Example) Embodiments of the present invention will be described below based on the drawings.

The resin molding apparatus shown in FIG. 1 has two gates.

In this apparatus, 1 and 2 are divided molds forming a cavity 8 for obtaining a resin molded product, 3 is a nozzle for discharging the resin material into the cavity 8, and 4 is a gate 5 provided in the mold 2. A hot runner 6 is provided between the nozzle 3 and the gate member 4 and is heated separately by a heating means (not shown).

7 is a support plate that supports the hot runner 6 on the mold 2.

The hot runner 6 has a nozzle connection part 11 connected to the nozzle 3 and a gate connection part 1 connected to each gate 5.
2, and flexible pipes 13.degree. 13 connecting this nozzle connection section 11 and each gate connection section 12.

The nozzle connection part 11 is fixed at a fixed position in the mold 2 by the support plate 7, and includes an inlet 14 for resin material connected to the discharge port 3a of the nozzle 3. The resin material inflow passage 15 extending from this inlet 14 toward the cavity 8 of the mold 2 branches into two parts (T-shaped), and a resin material inflow passage 15 is provided at the branched end in parallel with the cavity 8 of the mold 2. One end of each of the pipes 1313 is connected.

As shown in FIG. 2, the gate connecting portion 12 has a cylindrical shape, and one end surface thereof is in surface contact (or in contact with the line I!) with the gate member 4, and a resin material outflow passage 1 is formed inside the gate connecting portion 12.
6 is formed in an L-shape so that one end thereof is opened at one end surface of the gate connection section 12 and the other end thereof is opened at a side surface of the gate connection section 12. That is, the other end of the pipe 13 is connected to one end of the resin material outflow passage 16 opened on the side surface of the gate connection portion 12, and the other end of the resin material outflow passage 16, that is, the outflow port 17 is connected to the resin material outflow passage 16 of the gate 5. It is connected to the inlet 5a so as to wrap around it. In this case, inlet 5 of gate 5
a is formed to have a larger diameter than the outlet 17 of the gate connection portion 12 .

Then, the outlet 1 at one end of the gate connection part 12
7, that is, the contact surface 12a with the gate member 4,
The contact surface 4a of the gate member 4 at the periphery of the injection port 5a of the gate 5 is formed as a concave spherical surface. That is, the contact surface 12a of the gate connection part 12 and the contact surface 4a of the gate member 4 are in spherical contact,
As a result, the gate connecting portion 12 wraps its outlet 17 around the injection port 5a of the gate 5, so that the pipe 13 is curved by elongation in the longitudinal direction due to its thermal expansion. It can be rotated in any condition.

Note that when the radius of curvature of the contact surface 12a of the gate connecting portion 12 is smaller than the radius of curvature of the contact surface 4a of the gate member 4, the contact surface 12a of the gate connecting portion 12 is located at the opening edge of the injection port 5a of the gate 5. The line will come into contact with the line.

Further, as shown in FIG. 3, the gate connection portion 12 is
It is pressed and held against the gate member 4 by a leaf spring 19 passed between a pair of support columns 18 and 18 set upright on the mold 2.

Therefore, in the hot runner 6, when the resin is heated during molding, the pipe 13 extends in the longitudinal direction starting from the nozzle connecting portion 11 due to its thermal expansion.

At this time, the gate connecting portion 12 receives the force due to this elongation from the pipe 13, and slides its convex spherical contact surface 12a on the concave spherical contact surface 4a of the gate member 4, as shown in FIG. As a result, the outlet 17 of the gate 5 is rotated about the position of the inlet 5a with the outlet 17 wrapped around the inlet 5a. As a result, the pipe 13 is smoothly curved as shown in FIG.

In other words, the elongation due to thermal expansion of the pipe 13 is absorbed by the rotation of the gate connection part 12 and the curvature of the pipe 13.
The position of the outlet 17 of the gate connection part 12 and the position of the inlet 5a of the gate 5 are substantially unchanged before and after thermal expansion. Further, in this case, the leaf spring 19 is connected to the gate connecting portion 12.
Since the gate connecting portion 12 is pressed against the gate member 4 while allowing rotation of the gate connecting portion 12, the contact surface 12a of the gate connecting portion 12
slides on the contact surface 4a of the gate member 4 while maintaining surface contact (or line contact), which improves the sealing performance between the outlet 17 of the gate connection part 12 and the inlet 5a of the gate 5. is not damaged.

FIG. 6 shows another example of means for pressing the gate connection portion 12. That is, this pressing means is a coil spring 21 interposed between the support plate 7 and the gate connection part 12.
It is composed of:

7 and 8 show a hot runner 22 applied to a four-point gate resin molding apparatus. That is, in this case, four pipes 24 extend in the radial direction from one nozzle connection part 23, and a gate connection part 25 is connected to the tip of each pipe 24. In this case, the only difference from the previous embodiment is that the resin material inflow passage extending from the inlet 26 of the nozzle connection part 23 is divided into four directions, and the other configurations are the same.

9 and 10 show a hot runner 32 applied to a one-point gate resin molding apparatus. That is, this device is used when one gate connecting portion 35 is connected to a nozzle connecting portion 33 by a pipe 34, and the nozzle position and the gate position are offset in a direction perpendicular to their respective longitudinal directions. It is something to do.

Note that even if the nozzle and gate are not offset, if they are far apart, the nozzle connecting part and the gate connecting part can be connected with a pipe, and the thermal expansion of this pipe can be absorbed by its curvature. I can do it. In that case, there is no need for suppression means for the gate connection.

Further, in the above embodiment, the contact surface is made into a spherical surface in order to make the gate connection part rotatable, but it may be a simple arcuate surface.

Furthermore, in the above example, the gate connection part was made rotatable, but this gate connection part is fixed to the mold in the same way as the nozzle connection part, and the longitudinal elongation due to thermal expansion is absorbed only by bending the pipe. You may also do so. In that case,
A pipe that is relatively easy to target may be used, or the pipe may be curved in advance so that the curve (the radius of curvature becomes smaller) during thermal expansion is performed smoothly.

Furthermore, the present invention is not limited to the above embodiments, but
Of course, the present invention can also be applied to multi-point gates with three or five or more gates.

[Brief explanation of drawings]

1 to 10 show embodiments of the present invention, FIG. 1 is a sectional view of a hot runner type resin molding apparatus, FIG. 2 is an enlarged sectional view of a gate portion, and FIG. 3 is an enlarged sectional view of a gate connection portion. Fig. 1 is a view taken in the direction of the ■ arrow in Fig. 1 to show the pressing means, Fig. 4 is a sectional view showing the rotating state of the gate connection part, Fig. 5 is a side view showing the bent state of the pipe, and Fig. 6 is the gate. FIG. 7 is a plan view showing a hot runner in the case of a four-point gate; FIG. 8 is a diagram similar to FIG.
Figure 9 is a plan view showing a hot runner with one point gate, Figure 10 is a cross-sectional view taken along line X-X in Figure 9, and Figure 11 is a conventional hot runner type resin. 12 is an enlarged sectional view showing the gate connection portion of a conventional hot runner before thermal expansion; FIG. 13 is an enlarged sectional view showing the gate connection portion of the runner after thermal expansion. . 1.2...Mold 3...Nozzle 3a...Discharge port 4...Gate member 5...Gate 5a...・・Inlet 6.22.32・・・・Hot runner-11, 23
, 33... Nozzle connection part 12.25.35...
... Gate connection part 12a ... Contact surface 13.24.34 ... Pipe 14 ... Inflow port 17 ... Outflow port 19 ... ...Plate spring 1゜2 ...Mold 3 ...Nozzle 11゜3a ...Discharge port 4 ...Gate member 5 ...Gate 5a... Inlet 22.32... Hot runner 23, 33... Nozzle connection part 25.35... Gate connection part 12a...・Contact surface 24.34... Pipe 14... Inflow port 17... Outlet port 19... Leaf spring 65- Fig. 9 Fig. 10 Fig. 11 Figure 13

Claims (3)

[Claims] (1) A hot runner that constitutes a flow path for sending the resin material received from the molding machine to the gate of the mold, and an inlet for the resin material connected to the discharge port of the molding machine;
The resin molding has a resin material outlet connected to the inlet of the gate, and is composed of a flexible pipe that absorbs longitudinal elongation due to thermal expansion by curving. hot runner. (2) The end on the inlet side is fixed at a fixed position with respect to the mold, and the contact surface with the gate is stretched around the inlet position of the gate due to the longitudinal elongation due to thermal expansion of the pipe. The resin-molded hot runner according to claim 1, wherein the resin-molded hot runner is formed into an arcuate surface so as to rotate. (3) Claim in which the gate is pressed by a spring (
The hot runner for resin molding according to 1) or (2).