JP2014091313A - Hot runner apparatus of injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot runner apparatus of an injection molding machine in which even if heat expansion and heat shrinkage are generated at a hot runner side, that excessive flexural stress is generated in a nozzle can be suppressed.SOLUTION: A hot runner apparatus includes: a nozzle 16 that has channels 181, 182 of a molten resin inside between a tip 19 and a base end part 20, and injects a molten resin introduced from the base end part from the tip toward an apertural area 14 of a cavity 13 of molding tools 11, 12; a hot runner block 21 in which the base end part of the nozzle is fixed, and a channel 22 that guides the molten resin to a channel of the nozzle is formed; and a closing pin 23 that opens and closes a channel of the nozzle, wherein the nozzle 16 includes: a first nozzle 161 that is fixed so as to thermally contact to the molding tools and has the tip; and a second nozzle 162 that is fixed so as to thermally contact to the hot runner block and has the base end part, and the first nozzle and the second nozzle are subjected to pressure-contacting to be tilted centering a joint area 17.

Description

  The present invention relates to a hot runner device for an injection molding machine.

  In the hot runner type injection molding machine, the gate is displaced due to a temperature difference between the hot runner side (high temperature) and the mold side (low temperature). In order to solve this problem, the base of the nozzle with the tip opening facing the gate of the cavity block is fixed to the manifold, a seal ring is fitted to the tip outer peripheral surface of the nozzle, and a hole that is in sliding contact with the outer periphery of the seal ring is formed. There is known a hot runner device in which the provided slide ring is slidably fitted in a recess provided in a joint surface portion between a fixed side mold plate and a cavity block in a lateral direction (Patent Document 1).

JP 2002-113746 A

  However, in the conventional hot runner apparatus, since the nozzle itself moves in accordance with the thermal expansion of the manifold, the deviation between the nozzle tip position and the proximal position is absorbed by the deflection of the nozzle itself. Therefore, depending on the length of the nozzle and the amount of thermal expansion of the manifold, there is a problem in that a large bending stress is generated by the deflection of the nozzle.

  The problem to be solved by the present invention is to provide a hot runner device for an injection molding machine that can prevent excessive bending stress from being generated in a nozzle even if thermal expansion or contraction occurs on the hot runner side.

  According to the present invention, the first nozzle fixed so as to be in thermal contact with the mold and the second nozzle fixed so as to be in thermal contact with the hot runner block are press-contacted with a tiltable joint surface. Solve the above problems.

  According to the present invention, even if the base end portion of the second nozzle fixed to the hot runner block is thermally expanded, the first nozzle and the second nozzle are relatively inclined at the joint surface. Therefore, bending stress acting on the nozzle can be suppressed.

It is sectional drawing which shows the injection molding machine (at the time of shaping | molding) to which the hot runner apparatus which concerns on one embodiment of this invention is applied. It is an expanded sectional view which shows the front-end | tip part of the nozzle of FIG. It is sectional drawing which shows the state at the time of normal temperature of the injection molding machine of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a state during molding of an injection molding machine 1 to which a hot runner apparatus according to an embodiment of the present invention is applied. The injection molding machine 1 of this example includes a first mold 11 and A second molding die 12 is provided, and the first molding die 11 and the second molding die are relatively close to each other and are clamped to form a cavity 13 therein. An opening 14 is formed in the cavity 13. Molten resin is injected through the At the time of molding, the injected resin is cooled by circulating cooling water through water jackets provided in the first molding die 11 and the second molding die 12, respectively.

  In the injection molding machine 1 of the present example, the first mold 11 is a fixed mold fixed to a base (not shown), the second mold 12 is a movable mold fixed to a driving device (not shown), and the second mold The mold 12 is provided so as to be capable of reciprocating between a position where the mold 12 approaches the first mold 11 and a position where the mold 12 moves away from the first mold 11. The first mold 11 and the second mold 12 need only be driven between a relatively close position for clamping and a relatively spaced position for opening the mold. The first mold 11 may be a movable mold, the second mold 12 may be a fixed mold, or both the first mold 11 and the second mold 12 may be movable.

  A cavity 15 is formed at one end of the first mold 11 of this example, and a nozzle 16 is provided here. A hot runner block 21 for introducing the molten resin into the nozzle 16 is provided at a position close to the first mold 11.

  The hot runner block 21 has a flow path 22 of molten resin formed therein, and the right end thereof is connected to an injection device (not shown) having a function of plasticizing, reducing the weight of the resin, and injecting it. A predetermined amount and a predetermined pressure of molten resin are supplied from the injection device to the flow path 22 of the hot runner block 21. The hot runner block 21 is provided with a heater such as a band heater or a cartridge heater in order to maintain the resin melted by the injection device at a predetermined temperature. The hot runner block 21 of this example is not fixed to the first mold 11 but is fixed to a base outside the figure, and when it is thermally expanded or contracted, the first mold 11 is shown in FIG. The position is shifted in the X direction.

  The nozzle 16 of this example is fixed to the first mold 11 so as to be in thermal contact with the first mold 11 and is in thermal contact with the first nozzle 161 including the tip 19 and the hot runner block 21. And the second nozzle 162 including the proximal end portion 20. A flow path 181 through which the molten resin flows is formed inside the first nozzle 161, and a flow path 182 through which the molten resin flows is formed inside the second nozzle 162, and the two flow paths 181, 182 communicates. Similarly to the hot runner block 21, a heater such as a band heater or a cartridge heater is provided in order to maintain the resin melted by the injection device at a predetermined temperature.

  The lower end of the first nozzle 161 shown in FIG. 1 and the upper end of the second nozzle 162 are press-contacted so as to be tiltable about the joint surface 17. The joining surface 17 may be in a shape in which the second nozzle 162 is inclined with respect to the direction of thermal expansion and contraction of the hot runner block 21, that is, the X direction shown in FIG. It is desirable to comprise a curved surface. In particular, it is desirable to set the installation position of the second nozzle 162 so that the pressure acts on the first nozzle 161 when the nozzle 16 and the hot runner block 21 are at room temperature. By doing so, when the nozzle 16 expands during molding, the bonding pressure between the first nozzle 161 and the second nozzle 162 on the bonding surface increases, and the sealing property of the molten resin is enhanced.

  Opening and closing pins 23 for opening and closing the flow paths 181 and 182 are provided so as to be able to advance and retreat so as to be substantially orthogonal to the flow paths 181 and 182 of the molten resin formed inside the nozzle 16. The opening / closing pin 23 is driven by an actuator 24 such as a hydraulic cylinder between a position where the flow path 181, 182 moves forward to close and a position where the flow path 181, 182 moves backward to open. . The actuator 24 of this example is fixed to the side wall surface of the first mold 11, and the opening / closing pin 23 penetrates the first mold 11 horizontally and further passes through the first nozzle 161 as shown in FIG. The flow path 181 of the first nozzle 161 is provided to open and close.

Next, the operation will be described.
FIG. 1 is a cross-sectional view showing an injection molding machine 1 at the time of molding for heating the hot runner block 21 and the nozzle 16, and FIG. 3 is an injection molding machine 1 at normal temperature when the heating of the hot runner block 21 and the nozzle 16 is stopped. FIG. First, for example, at the time of molding shown in FIG. 1, that is, in a state where the hot runner block 21 is thermally expanded and shifted to the left in the X direction in the figure, the axis of the flow path 181 of the first nozzle 161 and the second nozzle 162 The positional relationship among the hot runner block 21, the first molding die 11, and the nozzle 16 is set so that the axial center of the flow path 182 is in a straight line. Thereby, shaping | molding can be implemented in the state in which a bending stress does not act on the nozzle 16, and the leakage of molten resin can also be prevented.

  At the time of molding, the hot runner block 21 and the nozzle 16 are heated in a state where the opening / closing pin 23 is driven to the forward position and the flow path 181 of the first nozzle 161 is closed, and a predetermined amount and a predetermined pressure are supplied from an injection device (not shown). The molten resin is introduced into the flow path 22 of the hot runner block 21 → the flow path 182 of the second nozzle 162 → the flow path 181 of the first nozzle 161. In parallel with this, the second mold 12 is lowered and clamped with the first mold 11. Then, by driving the open / close pin 23 to the retracted position, the molten resin is injected into the cavity 13 from the opening 14, and at the same time, by the cooling water that has flowed into the water jackets of the first mold 11 and the second mold 12. To be cooled.

  At the time of this molding, the hot runner block 21 is heated by the heater, so that it thermally expands in the X direction shown in FIG. 1, but in the thermally expanded state, the axis of the flow path 181 of the first nozzle 161 and the second nozzle Since it is set so that the axial center of the flow path 182 of 162 coincides, an excessive bending stress does not act on the nozzle 16, and leakage of the molten resin from the joint surface 17 is also prevented. Further, in this example, the distal end portion 19 of the first nozzle 161 is fixed to the first mold 11 and the proximal end portion 20 of the second nozzle 162 is fixed to the hot runner block 21. Leakage is also prevented.

  When the molding is finished, the hot runner block 21 and the heater of the nozzle 16 are turned off. As a result, the hot runner block 21 is thermally contracted in the X direction as shown in FIG. At this time, since the base end portion 20 of the second nozzle 162 is fixed to the hot runner block 21 by means such as screwing, the base end portion 20 of the second nozzle 162 is caused by the thermal contraction of the hot runner block 21. The second nozzle 162 is inclined with respect to the first nozzle 161 fixed to the first molding die 11 with the joint surface 17 as the center, although the second nozzle 162 is inclined to the right in the X direction shown in FIG. Thereby, it is possible to suppress an excessive bending stress from acting on the nozzle 16 (particularly the second nozzle 162). As shown in FIG. 3, the axial center of the flow path 182 of the second nozzle 162 is inclined with respect to the axial center of the flow path 181 of the first nozzle 161. However, since the state shown in FIG. The problem of leakage does not occur.

  As described above, according to the hot runner device of the injection molding machine of this example, the first nozzle 161 is airtightly fixed to the first mold 11, and the base end portion 20 of the second nozzle 162 is airtightly connected to the hot runner block 21. In addition, since the joining surfaces of the first nozzle 161 and the second nozzle 162 are also pressure-welded and joined in an airtight manner, leakage of the molten resin during molding can be prevented.

  Further, the position of the base end portion 20 of the second nozzle 162 is also shifted according to the thermal expansion and thermal contraction of the hot runner block 21, but the second nozzle 162 is in the joint surface 17 with respect to the first nozzle 161. As a result, it is possible to suppress an excessive bending stress from acting on the nozzle 16, particularly the second nozzle 162.

  Further, according to the hot runner apparatus of this example, the open / close pin 23 that opens and closes the flow paths 181 and 182 of the nozzle 16 is not the inside of the nozzle 16 but the thermal expansion and thermal contraction of the hot runner block 21. Since it is provided at a site that is not affected by tilting, it is possible to prevent interference between the opening / closing pin 23 and the opening 14.

  Further, according to the hot runner apparatus of this example, the opening / closing pin 23 and its actuator 24 are provided along the direction orthogonal to the extending direction of the nozzle 16 from the side wall surface of the first mold 11. The height direction (vertical direction in FIG. 1) can be lowered. Further, since the access to the open / close pin 23 and the actuator 24 becomes easy, maintenance workability is also improved.

DESCRIPTION OF SYMBOLS 1 ... Injection molding machine 11 ... 1st shaping | molding die 12 ... 2nd shaping | molding die 13 ... Cavity 14 ... Opening part 15 ... Cavity part 16 ... Nozzle 161 ... 1st nozzle 162 ... 2nd nozzle 17 ... Joining surface 181,182 ... Nozzle Nozzle channel 19 ... Nozzle tip 20 ... Nozzle proximal end 21 ... Hot runner block 22 ... Hot runner block channel 23 ... Opening / closing pin 24 ... Actuator

Claims (4)

A nozzle that has a flow path of a molten resin inside the distal end portion and the proximal end portion, and injects the molten resin introduced from the proximal end portion toward the opening of the cavity of the mold from the distal end portion; ,
A hot runner block in which a base end portion of the nozzle is fixed and a flow path for guiding the molten resin to the flow path of the nozzle is formed;
An open / close pin that opens and closes the flow path of the nozzle,
The nozzle is
A first nozzle fixed in thermal contact with the mold and including the tip;
A second nozzle that is fixed in thermal contact with the hot runner block and includes the base end;
The hot runner device of an injection molding machine, wherein the first nozzle and the second nozzle are press-contacted so as to be tiltable about a joint surface.   The hot runner apparatus for an injection molding machine according to claim 1, wherein a joint surface between the first nozzle and the second nozzle is formed of a curved surface.   The hot runner device for an injection molding machine according to claim 1 or 2, wherein the open / close pin moves forward and backward along a direction perpendicular to the flow path of the nozzle outside the flow path of the nozzle.   The hot runner apparatus for an injection molding machine according to claim 3, wherein the opening / closing pin opens and closes a flow path of the first nozzle.

Images