JP2750154B2 - Hot runner for resin molding - Google Patents

Description

The present invention relates to a hot runner for a resin molding apparatus.

(Prior Art) In a resin molding apparatus, a hot runner method is generally known in which a runner provided between a nozzle and a gate is not cooled every cycle, but only a molded product side from a gate is separated and cooled and taken out. Have been.

An example of the structure of the hot runner is shown in FIG. 11 to FIG. That is, this hot runner a
A thick iron plate is drilled to form a resin material passage f having an inlet b connected to a nozzle and an outlet e connected to a gate d of a mold c. in this case,
The hot runner a has a portion at the inflow port b fixed to the support plate g, and a slide holding member h for allowing elongation due to thermal expansion between the mold c and the support plate g. The outlet e which is held and does not match the inlet i of the gate d at the time of cooling as shown in FIG. 12 is configured to match by elongation due to thermal expansion at the time of heating as shown in FIG. .

(Problems to be Solved by the Invention) Therefore, in the case of the conventional hot runner described above, since the elongation due to the thermal expansion is allowed by the slide mechanism, the outflow port is aligned with the gate without thermal displacement during the thermal expansion. In order to do 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 form a hole in the iron plate to form a resin material passage. Therefore, as the number of gates increases, the processing becomes more difficult and the hot runner itself becomes heavy. Become something. Such a problem becomes more remarkable as the size of the hot runner becomes larger, and the hot runner is usually more expensive due to the above-described requirement of high dimensional accuracy and difficulty in processing. .

That is, an object of the present invention is to make it possible to allow elongation due to thermal expansion of a hot runner with a simple structure without the above-mentioned problem.

(Means for Solving the Problems) In order to solve such a problem, the present invention absorbs the elongation due to the thermal expansion of the hot runner by the curvature of the hot runner itself, so that the outlet of the hot runner and the inlet of the gate are absorbed. Are intended to prevent the displacement due to the thermal expansion.

That is, a means described in claim 1 for this is a hot runner that forms a flow passage for sending the resin material received from the molding machine to the gate of the mold, and is connected to a discharge port of the molding machine. It has an inflow port of the resin material and an outflow port of the resin material connected to the injection port of the gate, and is constituted by a flexible pipe that absorbs by bending the longitudinal elongation due to thermal expansion by bending. It is characterized by the following.

The means according to claim (2) is the hot runner according to claim (1), wherein the end on the inflow side is fixed to a fixed position with respect to the mold, and the contact surface with the gate is: It is characterized in that the pipe is formed in an arc surface so as to rotate around the inlet position of the gate by elongation in the longitudinal direction due to thermal expansion of the pipe.

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

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

In the hot runner according to claim (2), when the gate connection portion and the gate are in contact with each other on an arc surface, and the pipe extends in the longitudinal direction due to thermal expansion, the gate connection portion exerts a force due to the extension from the pipe. In response to this, the gate rotates about the inlet position of the gate, thereby bending the pipe. In other words, the expansion due to the thermal expansion of the pipe is absorbed by the rotation of the gate connection and the bending of the pipe, and the position of the outlet of the gate connection and the position of the inlet of the gate are substantially before and after the thermal expansion. Does not change.

In the hot runner according to the third aspect, since the gate connecting portion is pressed by the gate by the spring, the resin leaks against the pressure of the resin material while allowing the rotation of the gate connecting portion. The gate connection portion can be pressed against the gate without the need.

(Effect of the Invention) Therefore, according to the invention described in claim (1), a part of the hot runner is constituted by a pipe, and this pipe is curved at the time of its thermal expansion. A substantial change in the position of the gate connecting portion before and after the above can be prevented, so that high dimensional accuracy is not required for the hot runner itself, and furthermore, a slide mechanism as in the related art is unnecessary and a pipe can be used. This simplifies or reduces the weight of the hot runner, facilitates the manufacture of the hot runner, and reduces the manufacturing cost.

According to the invention described in claim (2), the gate connecting portion is brought into contact with the gate by an arc surface, and the pipe is curved by rotating around the inlet position of the gate when the pipe is thermally expanded. As a result, the pipes are smoothly curved without incurring excessive deformation due to the rotation of the gate connection part, while maintaining the sealing property between the gate connection part and the gate, thereby preventing local stress concentration of the pipe. Thus, the durability can be improved.

In the hot runner according to the third aspect, since the gate connecting portion is pressed against the gate by the spring, the resin material can be prevented from leaking while allowing the gate connecting portion to rotate. .

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

The resin molding apparatus shown in FIG. 1 has a two-point gate. In the apparatus, reference numerals 1 and 2 denote split molds forming a cavity 8 for obtaining a resin molded product, and reference numeral 3 denotes a cavity 8
A nozzle 4 for discharging a resin material into the mold 2 is a gate member provided on the mold 2 to form a gate 5, and is separately heated by a heating means (not shown) between the nozzle 3 and the gate member 4. Hot runner 6 is provided. Reference numeral 7 denotes a support plate for supporting the hot runner 6 on the mold 2.

The hot runner 6 includes a nozzle connecting portion 11 connected to the nozzle 3 and a gate connecting portion 12 connected to each gate 5.
And flexible pipes 13, 13 connecting the nozzle connecting portion 11 and each gate connecting portion 12.

The nozzle connecting portion 11 is fixed to a fixed position of the mold 2 by the support plate 7 and has an inlet 14 for a resin material connected to the outlet 3 a of the nozzle 3. The resin material inflow passage 15 extending from the inflow port 14 toward the cavity 8 of the mold 2 is branched into two hands (T shape), and is provided at the branch end in parallel with the cavity 8 of the mold 2. Pipe 13,13
Are connected at one end.

As shown in FIG. 2, the gate connecting portion 12 has a cylindrical shape, and one end surface thereof is in surface contact (or line contact) with the gate member 4, and a resin material outflow passage 16 is provided therein. On one end face of the gate connection section 12 and the other end on the gate connection section.
It is formed in an L shape so as to open on each of the 12 side surfaces. That is, the other end of the pipe 13 is coupled to one end of the resin material outflow passage 16 opened on the side surface of the gate connection portion 12,
The other end of the resin material outflow passage 16, that is, the outflow port 17 is connected so as to wrap around the resin material injection port 5 a of the gate 5. In this case, the inlet 5 a of the gate 5 is formed to have a larger diameter than the outlet 17 of the gate connection 12.

Then, the outlet 17 at one end of the gate connection portion 12
, That is, the contact surface 12a with the gate member 4 is formed as a convex spherical surface, while the contact surface 4a of the gate member 4 at the peripheral edge of the inlet 5a of the gate 5 is formed as a concave spherical surface.
That is, the contact surface 12a of the gate connection portion 12 and the gate member 4
Is in spherical contact with the contact surface 4a of the gate 5, so that the gate connecting portion 12 is formed so that the pipe 13 is curved by elongation in the longitudinal direction due to its thermal expansion.
The outlet 17 can be rotated around the position 5a with the outlet 17 wrapped around the inlet 5a.

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
Will come into line contact with the opening edge.

In addition, as shown in FIG.
Leaf spring 19 passed between a pair of columns 18 and 18 erected on the mold 2
As a result, it is pressed and held by the gate member 4.

Therefore, when the hot runner 6 is heated during resin molding, the pipe 13 extends in the longitudinal direction from the nozzle connection 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, as shown in FIG.
By sliding a on the concave spherical contact surface 4 a of the gate member 4, the gate 5 rotates around the position of the inlet 5 a with the outlet 17 wrapped around the inlet 5 a. As a result, the pipe 13 is smoothly curved as shown in FIG.

In other words, the expansion due to the thermal expansion of the pipe 13 is absorbed by the rotation of the gate connecting portion 12 and the curvature of the pipe 13, and the position of the outlet 17 of the gate connecting portion 12 and the position of the inlet 5a of the gate 5 are thermally It does not substantially change before and after expansion. In this case, since the leaf spring 19 presses the gate connecting portion 12 against the gate member 4 while allowing the gate connecting portion 12 to rotate, the contact surface 12a of the gate connecting portion 12 is 4a is slid while maintaining surface contact (or line contact) on the upper surface 4a.
The sealing performance with the injection port 5a is not impaired.

FIG. 6 shows another example of the means for pressing the gate connection portion 12. As shown in FIG. That is, the pressing means is constituted by a coil spring 21 interposed between the support plate 7 and the gate connecting portion 12.

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

9 and 10 show a hot runner 32 applied to a one-point gate resin molding apparatus. That is, in this case, one gate connection portion 35 is connected to the nozzle connection portion 33 by the pipe 34.
This is used when the nozzle position and the gate position are offset in a direction orthogonal to the respective longitudinal directions.

Even when the nozzle and the gate are not offset, if the nozzle and the gate are separated from each other, the nozzle connection and the gate connection are connected by a pipe, and the thermal expansion of the pipe is absorbed by its curvature. Can be. In that case, the pressing means of the gate connection part is unnecessary.

Further, in the above embodiment, the contact surface is spherical in order to make the gate connecting portion rotatable, but it may be a simple arc surface.

Further, in the above embodiment, the gate connection portion is made rotatable. However, this gate connection portion is fixed to the mold in the same manner as the nozzle connection portion, and the longitudinal expansion due to thermal expansion is absorbed only by bending the pipe. You may make it. In this case, a pipe that is relatively easily bent may be used, or the pipe may be curved in advance so that the curvature (the radius of curvature is reduced) during thermal expansion is smoothly performed. Good.

Further, it goes without saying that the present invention is not limited to the above embodiment, but can be applied to a multipoint gate having three or five or more gates.

[Brief description of the drawings]

1 to 10 show an embodiment 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. FIG. 4 is a sectional view showing a rotating state of a gate connecting portion, FIG. 5 is a side view showing a curved state of a pipe, and FIG. FIG. 7 is a view similar to FIG. 3 showing another example of the pressing means of the portion, FIG. 7 is a plan view showing a hot runner in the case of a four-point gate, and FIG.
FIG. 9 is a plan view showing a hot runner in the case of a one-point gate, FIG. 10 is a cross-sectional view taken along the line XX of FIG. 9, and FIG. 11 is a conventional hot runner type resin molding. FIG. 12 is an enlarged sectional view showing a gate connecting portion of the conventional hot runner before thermal expansion, and FIG. 13 is an enlarged sectional view showing a gate connecting portion of the conventional hot runner after thermal expansion. 1,2 mold 3 nozzle 3a discharge port 4 gate member 5 gate 5a injection port 6,22,32 hot runner 11,23,33 nozzle connection 12 , 25,35… Gate connection part 12a… Contact surface 13,24,34… Pipe 14… Inlet 17… Outlet 19… Leaf spring

Claims (3)

(57) [Claims] 1. A hot runner constituting a flow passage for feeding a resin material received from a molding machine to a gate of a mold, comprising: an inlet for a resin material connected to a discharge port of the molding machine;
A resin pipe having an outlet for a resin material connected to the inlet of the gate, wherein the pipe is formed by a flexible pipe that absorbs by bending a longitudinal expansion due to thermal expansion. Hot runner. 2. An end on the inlet side is fixedly provided at a fixed position with respect to a mold, and a contact surface with a gate is provided at a position of an inlet of the gate by elongation in a longitudinal direction due to thermal expansion of a pipe. The resin molded hot runner according to claim 1, wherein the hot runner is formed on an arc surface so as to rotate about a center. 3. The resin-molded hot runner according to claim 1, wherein the gate is pressed by a spring.