JP2010162714A - Injection nozzle of injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection nozzle of a rubber injection molding machine, wherein a rubber material is allowed to efficiently generate heat when passing the injection nozzle, so that the temperature of the rubber material to be injected into a mold can be made higher than before and an injection molding cycle time can be shortened and the calorific value of the rubber material or the extent of raising temperature thereof can be controlled easily as needed. <P>SOLUTION: The injection nozzle 30 of the injection molding machine for injecting the rubber material packed in an injection chamber of an injection cylinder 24 into the mold is composed of: a nozzle body 36 having a nozzle orifice 48 at the tip thereof; and a friction heat generator 38 which is arranged separately from the nozzle body 36, is inserted fittingly into a recessed portion 44 of the nozzle body 36 and has a porous structure having many pores 52. The rubber material is made to pass through many pores 52 to the axial direction to generate frictional heat, further made to pass through the nozzle orifice 48 to generate heat and supplied to the mold. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an injection nozzle of an injection molding machine that injects a rubber material into a molding die.

Conventionally, an injection molding machine has been widely used as a molding machine for rubber molded products.
In this injection molding machine, the rubber material filled in the injection chamber inside the injection cylinder is injected from the injection nozzle at the tip of the injection cylinder into a mold and molded into a predetermined shape.
At this time, the rubber material generates heat by a frictional force between the rubber material and the inner peripheral surface of the injection nozzle in the process of passing through the injection nozzle, and is injected into the mold after the temperature is raised.

FIG. 6 shows a specific example of a conventional injection nozzle.
In the figure, 200 is a mold, 202 is an injection cylinder, and 204 is an injection nozzle.
The injection nozzle 204 has a male screw 206 on the outer peripheral surface on one end side in the axial direction (upper end side in the figure). The male screw 206 is screwed to the injection cylinder 202 and attached.
The injection nozzle 204 has a cylindrical shape as a whole, and has a recess 208 as a passage space for the rubber material therein.
Further, a nozzle hole 210 having a diameter smaller than that of the recess 208 is provided at the distal end portion and communicated with the recess 208.

In an injection molding machine equipped with such an injection nozzle 204, a rubber material filled in an injection chamber inside the injection cylinder passes through the injection nozzle 204 and is injected into the mold 200.
At this time, the flow of the rubber material is restricted by the nozzle hole 210 of the injection nozzle 204, and heat is generated based on a large frictional force generated between the rubber material and the inner peripheral surface of the nozzle hole 210 when passing through the nozzle hole 210. Can be warmed.

  At this time, the temperature rise temperature of the rubber material is higher, and the closer to the vulcanization temperature, the shorter the time required for heating the rubber material inside the mold 200, and the molding cycle for vulcanization molding of the rubber molded product. Time can be shortened and productivity can be increased.

  However, in the case of the conventional injection nozzle 204, the rubber material generates frictional heat only when the rubber material passes through the nozzle hole 210, and the heat generation generates frictional contact with the inner peripheral surface of the nozzle hole 210. The temperature of the rubber material is not sufficient because it is only the outer periphery, and the time required to heat the rubber material to the vulcanization temperature after reaching the inside of the mold becomes longer, and the molding cycle time becomes longer. There was a problem such as.

  However, it is possible to increase the heat generation of the rubber material in the nozzle hole 210 by changing the resistance of the nozzle hole 210 with respect to the rubber material, that is, to increase the temperature rise temperature of the rubber material. Only the heat generated by friction with the inner peripheral surface of the rubber material naturally has a limit even if the heat generation amount of the rubber material is increased and the temperature rise is increased, and the heating of the rubber material is limited to the outer peripheral portion of the portion passing through the nozzle hole 210. Since it is a partial heating, if it is going to raise the whole temperature, the outer peripheral part will be in an overheated state and the problem which raise | generates what is called rubber | gum will arise.

  In addition, in the case of the injection nozzle 204, only the outer peripheral portion of the rubber material passing through the nozzle hole 210 generates heat, and the central portion does not generate heat due to friction. Therefore, a temperature difference is generated between the outer peripheral portion and the inner peripheral portion. As a result, there was a problem that temperature unevenness occurred in the rubber material.

In addition, there exists what was disclosed by the following patent document 1 as a prior art with respect to this invention.
However, the one disclosed in Patent Document 1 has a complicated structure of the injection nozzle itself, requires a dedicated injection cylinder or injection device, and further, resistance when the rubber material passes through the injection nozzle and heat generation based on the resistance. This is different from the present invention in that it cannot be easily changed.

Another prior art is disclosed in Patent Document 2 below.
However, the one disclosed in Patent Document 2 is provided with an injection nozzle on the side of the mold and generates heat when the rubber material passes through the injection nozzle, which is also different from the present invention. belongs to.

JP-A-8-34034 JP 2008-105247 A

  The present invention is based on the circumstances as described above, and can efficiently generate heat when the rubber material passes through the injection nozzle without particularly modifying the structure of the conventional injection cylinder or injection nozzle. The temperature of the rubber material injected into the mold can be increased to a higher temperature than before, the molding cycle time can be shortened, and the amount of heat generated and the temperature rise of the rubber material can be easily adjusted as necessary. The invention has been made for the purpose of providing an injection nozzle in a rubber injection molding machine.

  Thus, the first aspect of the present invention is the injection nozzle of an injection molding machine for injecting the rubber material filled in the injection chamber inside the injection cylinder from the injection nozzle at the tip of the injection cylinder into the mold, (a) a nozzle body having a recess as a passage space for the rubber material inside and having a nozzle hole having a diameter smaller than that of the recess communicated with the recess; b) Separated from the nozzle body, inserted into the recess of the nozzle body and into the inner peripheral surface of the recess over the entire circumference, and extending in the axial direction. Two or more pores having a diameter smaller than that of the nozzle hole, which is in communication with the nozzle hole and causes the rubber material from the injection chamber to pass through in an axial direction to generate heat by friction, The nozzle holes are dispersed after passing through each of the pores. And a frictional heating element having a multi-hole structure to be led.

  According to a second aspect of the present invention, in the first aspect, the frictional heating element is provided in contact with a bottom portion of the recess in the nozzle body on the nozzle hole side, and each of the plurality of fine holes is provided. However, it is characterized in that as it proceeds forward on the nozzle hole side, it moves to the radial center side of the frictional heating element and converges to the nozzle hole.

  According to a third aspect of the present invention, in any one of the first and second aspects, on the rear end side of the frictional heating element, the front end is opened from the rear end opening opened toward the recess of the nozzle body. A mortar-like concave shape whose inner peripheral shape narrows along with it is continuous with each of the plurality of pores, and the rubber material reaching the recess from the injection chamber is collected and guided to each pore. The guide recesses to be provided are provided at positions corresponding to the respective pores and in a corresponding number.

Effects and effects of the invention

  As described above, according to the present invention, the injection nozzle is formed in a cylindrical shape and has a recess as a passage space for the rubber material therein, and the nozzle body having a nozzle hole and the nozzle body are separated from the nozzle body. It is inserted into the recess of the main body and fitted into the inner peripheral surface of the recess, extends in the axial direction and communicates with the nozzle hole, and causes the rubber material from the injection chamber to pass through in the axial direction to generate frictional heat. The friction of a multi-hole structure that has two or more pores having a diameter smaller than that of the nozzle hole, and that guides the nozzle material after passing through each pore by dispersing the rubber material into the plurality of pores And a heating element.

In the present invention, when the rubber material from the injection chamber passes through the injection nozzle, not only does it generate heat when the rubber material passes through the nozzle hole of the nozzle body, but also a frictional heating element inserted into the nozzle body. Even in the process of passing through the plurality of pores, heat is generated due to friction, and since each pore in the frictional heating element is smaller in diameter than the nozzle hole, heat is effectively generated in each pore.
In addition, since a plurality of pores are provided, the amount of heat generated when the rubber material passes through the frictional heating element is large, and the temperature of the rubber material at the time of injection and injection into the mold is increased as much as possible. Can approach the sulfur temperature.

  As a result, the time required for heating the rubber material inside the mold can be shortened, the molding cycle time of the rubber molded product can be effectively shortened, and the production efficiency can be increased.

  Further, in the present invention, when the rubber material passes through the pores of the frictional heating element, the effect of the pores (effect due to the narrow passage of the rubber material) causes the rubber material passing through the pores from the outer periphery. It is possible to heat up to the inside, and furthermore, since the rubber material is heated by being dispersed in a plurality of pores and passing therethrough, the heating of the entire rubber material can be equalized, and the temperature in the rubber material Unevenness can be reduced as much as possible.

  In addition, in the present invention, the frictional heating element is separated from the nozzle body, and is inserted into the recess of the nozzle body in a fitted state. Depending on the temperature, it is possible to easily adjust the resistance and the amount of heat generated when the rubber material passes through the injection nozzle to an appropriate one by replacing it with another different friction heating element such as the diameter and number of pores. Has features that can be.

  Further, in the present invention, it is only necessary to load the frictional heating element into the recess inside the nozzle body corresponding to the conventional injection nozzle, so without any modification to the structure of the conventional injection nozzle, injection cylinder or injection device, It has the advantage that it can be used as it is.

  Next, according to a second aspect of the present invention, the frictional heating element is provided in contact with the bottom of the nozzle body on the nozzle hole side, and each of the plurality of fine holes is caused to generate frictional heat as it advances forward on the nozzle hole side. The shape shifts toward the center of the body in the radial direction and converges to the nozzle hole.

By doing so, the rubber material that has passed through the plurality of pores stays in the rubber reservoir formed between the frictional heating element and the bottom of the recess, and the rubber is burnt, or the subsequent injection causes the rubber material to burn. The rubber material that has passed through the pores will surely flow into the nozzle holes and be supplied to the molding die without causing problems such as the burnt rubber in the rubber pool entering the inside of the molding die, leading to defective products of the rubber molded product. (In the present invention, such a rubber pool does not occur).
Accordingly, it is possible to surely prevent the rubber from being burnt in the rubber reservoir and supplying the burnt rubber into the mold, and it is possible to prevent the occurrence of product defects due to the mixture of the burned rubber.

  According to a third aspect of the present invention, a mortar-like shape is formed on the rear end side of the frictional heating element, the inner peripheral shape of which narrows toward the front from the rear end opening that opens toward the recess of the nozzle body. Concave shape that is continuous with each of the plurality of pores, and guide recesses for collecting and guiding the rubber material from the injection chamber to the recesses in the respective pores, corresponding to the positions corresponding to the respective pores. According to the third aspect, the rubber material from the injection chamber can be satisfactorily guided and collected in the respective pores of the frictional heating element and pass through the respective pores. It can be led to the nozzle hole, and it is possible to satisfactorily prevent the rubber material from staying there in the vicinity of the concave frictional heating element in the nozzle main body and staying there.

It is a figure of the principal part of the injection molding machine provided with the injection nozzle of one Embodiment of this invention. It is sectional drawing of the injection nozzle of the embodiment. It is a single-piece figure of the frictional heating element in the same embodiment. FIG. 4 is a cross-sectional perspective view of the frictional heating element of FIG. 3. It is a figure of other embodiment of this invention. It is the figure which showed an example of the conventional injection nozzle.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
In FIG. 1, 10 is a vertical rubber injection molding machine, 12 is an injection machine, 14 is an extruder, and 16 is a molding die comprising a mold.
The extruder 14 incorporates a screw 20 inside the extrusion cylinder 18 and plasticizes the tape-like rubber material supplied through the supply port 22 by the rotation of the screw 20 and pushes it out toward the injection machine 12.

  The injection machine 12 includes an injection cylinder 24 and a plunger 28 that injects a rubber material filled in an injection chamber 26 therein by forward movement, and an injection nozzle 30 is provided at the tip of the injection cylinder 24. Is provided.

In the rubber injection molding machine 10, the rubber material plasticized and extruded from the extruder 14 is filled into the injection chamber 26 inside the injection cylinder 24 with the backward movement of the plunger 28.
Then, when a predetermined amount of rubber material is extruded and supplied to the injection chamber 26 and filled, the plunger 28 moves forward, and the plasticized rubber material in the injection chamber 26 passes through the passage 32 of the injection cylinder 24 and the injection nozzle 30. Injected into the cavity 34 inside the mold 16.
The rubber material supplied to the cavity 34 is then heated and vulcanized for a predetermined time to form a rubber molded product.

FIG. 2 specifically shows the configuration of the injection nozzle 30.
As shown in the figure, the injection nozzle 30 includes a nozzle body 36 and a frictional heating element 38 having a porous structure separate from the nozzle body 36.
The nozzle body 36 has a cylindrical shape as a whole, and a male screw 40 is formed on the outer peripheral surface of the upper end portion in the figure. The male screw 40 is screwed into the female screw 42 of the injection cylinder 24 and is attached to the injection cylinder 24. ing.

  The nozzle body 36 has a recess 44 having a circular cross-section as a space through which the rubber material is passed, and has a partially spherical abutting contact with the mold 16 at the tip (lower end in the figure). A contact portion 46 is provided, and a tapered nozzle hole 48 is formed in the center of the contact portion 46.

The frictional heating element 38 having a porous structure is a member for generating heat and raising the temperature by forcibly passing a rubber material. As shown in FIGS. 2 and 3, the cross section has a circular shape and the vertical section has a rectangular shape. ing.
The frictional heating element 38 is inserted into the recess 44 so that the outer peripheral surface is fitted to the inner peripheral surface of the recess 44 over the entire circumference without any gap, and is attached to the nozzle body 36.
Here, the frictional heating element 38 is inserted into the recess 44 and mounted so that the lower surface in the drawing is in contact with the bottom 50 of the recess 44 without a gap.

The frictional heating element 38 is provided with a large number (six in this case) of pores 52 that extend in the axial direction and communicate with the nozzle holes 48 to cause the rubber material from the injection chamber 26 to pass through in the axial direction and generate frictional heat. It has been.
Here, each of the pores 52 has a smaller diameter than the nozzle hole 48, and as it advances forward (downward in the drawing) on the nozzle hole 48 side, toward the radial center of the frictional heating element 38. It shifts and converges in the nozzle hole 48, that is, a shape in which the tip opens in the nozzle hole 48.

The frictional heating element 38 is also provided with a large number (six in this case) of guide recesses 54 corresponding to the pores 52 in a form continuous with the pores 52 on the rear end side (upper end side in the figure). It has been.
Here, the guide recess 54 is a mortar-shaped recess whose rear end (upper end in the figure) opens toward the recess 44 of the nozzle body 36 and whose inner peripheral shape narrows as it advances forward from the rear end. It has a shape.
The guide recess 54 having a concave shape serves to collect and guide the rubber material reaching the recess 44 from the injection chamber 26 toward the respective pores 52.

Here, the guide recesses 54 basically have a mortar shape. However, as shown in FIG. 4, the guide recesses 54 are adjacent to each other and overlap each other in a mortar shape. The mortar-shaped concave shape is formed by cutting out the portion, and the above-described pore 52 corresponding to the bottom of the mortar-shaped concave shape is positioned.
In this embodiment, as shown in FIGS. 3A and 3C, the upper end in the drawing and the lower end in the drawing are centered on the central axes of the frictional heating element 38 and the nozzle hole 48, respectively. Are located on the same circumference.

  In this embodiment, when a predetermined amount of the rubber material extruded from the extruder 14 is filled in the injection chamber 26, the plunger 28 moves forward so that the rubber material in the injection chamber 26 is recessed in the nozzle body 36. 44 and each of the pores 52 of the frictional heating element 38 inserted therein and the nozzle hole 48 are then injected into the mold 16 and filled into the cavity 34.

At this time, the rubber material in the recess 44 is first collected into the corresponding pores 52 by the guide recesses 54 having a mortar-like concave shape of the frictional heating element 38, guided, and flows into the pores 52.
When the rubber material is forced to pass through the plurality of pores 52, the rubber material generates frictional heat there, and further, the rubber material that has passed through the pores 52 passes through the nozzle hole 48, and also generates heat there. And the entire rubber material is supplied to the mold 16 in a state where the temperature is raised.

In the present invention, as shown in FIG. 5, the frictional heating element 38 can be provided in a state of being separated from the bottom 50 of the recess 44 in the nozzle body 36.
However, in this case, the space between the frictional heating element 38 and the bottom 50 of the recess 44 becomes a rubber reservoir 56.

Therefore, the rubber material that has passed through the pores 52 of the frictional heating element 38 remains in the rubber reservoir 56 and stays there, which may cause rubber burning. Further, the burnt rubber in the rubber reservoir 56 enters the molding die 16 by the injection performed later, which causes a problem that the rubber molded product is defective.
However, in the case of the injection nozzle 30 configured in the form shown in FIGS. 2 and 3, there is an advantage that such a problem can be reliably prevented.

In the present embodiment as described above, when the rubber material from the injection chamber 26 passes through the injection nozzle 30, not only does it generate heat when the rubber material passes through the nozzle hole 48 of the nozzle body 36, but also the nozzle body 36. Because the frictional heating element 38 generates heat due to friction even in the process of passing through the numerous pores 52 of the frictional heating element 38 inserted therein, and each pore 52 in the frictional heating element 38 is smaller in diameter than the nozzle hole 48. Heat is effectively generated in each pore 52.
Moreover, since a plurality of the pores 52 are provided, the amount of heat generated when the rubber material passes through the frictional heating element 38 is large, and the temperature of the rubber material at the time of injection into the mold 16 and injection is made possible. Thus, the temperature can be brought close to the vulcanization temperature.

  As a result, the time required for heating the rubber material inside the mold 16 can be shortened, the molding cycle time of the rubber molded product can be effectively shortened, and the production efficiency can be increased.

  Furthermore, in this embodiment, when the rubber material passes through the pores 52 of the frictional heating element 38, the effect of the pores 52 (the effect due to the narrow passage of the rubber material) causes the rubber material to pass through the pores 52. On the other hand, it is possible to heat from the outer peripheral part to the inside, and furthermore, since the rubber material is heated by being dispersed in the plurality of pores 52 and passing therethrough, the heating of the entire rubber material can be equalized. Thus, temperature unevenness in the rubber material can be reduced as much as possible.

  In addition, in the present embodiment, the frictional heating element 38 is separate from the nozzle body 36 and is inserted into the recess 44 of the nozzle body 36 in a fitted state. Depending on the type or the required heating temperature, the resistance and heat value when the rubber material passes through the injection nozzle 30 can be changed by replacing the frictional heating element 38 with a different diameter and number of pores 52. It has the feature that it can be easily adjusted to anything.

  In the present embodiment, the frictional heating element 38 is simply loaded into the recess 44 inside the nozzle body 36 (corresponding to the conventional injection nozzle shown in FIG. 6). There is an advantage that the structure of the injection device can be used as it is without any modification.

Further, in the embodiment shown in FIGS. 1 to 4, the frictional heating element 38 is provided in contact with the bottom 50 on the nozzle hole 48 side of the recess 44 in the nozzle body 36, and each of the plurality of pores 52 is provided in the nozzle Since the shape of the frictional heating element 38 is shifted toward the center in the radial direction and converges to the nozzle hole 48 as it advances forward on the hole 48 side, the rubber material that has passed through the numerous pores 52 is rubbed. 5 stays in the rubber reservoir 56 shown in FIG. 5 between the heating element 38 and the bottom 50 of the recess 44, and the burnt rubber of the rubber reservoir 56 is injected into the mold 16 by the subsequent injection. The rubber material that has passed through the pores 52 can surely flow into the nozzle holes 48 and be supplied to the molding die 16 without causing the problem of entering and leading to product defects of the rubber molded product.
Accordingly, it is possible to prevent the occurrence of product defects by causing rubber burn in the rubber reservoir 56 and supplying the burned rubber into the mold 16.

  In the embodiment shown in FIGS. 1 to 4, the inner peripheral shape narrows toward the rear end side of the frictional heating element 38 from the rear end opening opened toward the recess 44 of the nozzle body 36 toward the front. A guide concave portion 54 is formed in a mortar-like concave shape having a round shape, and continuously gathers and guides the rubber material reaching the recess 44 from the injection chamber 26 to each of the plurality of pores 52. According to this embodiment, the rubber material from the injection chamber 26 is favorably introduced and guided into the respective pores 52 of the frictional heating element 38 since the number corresponding to each pore 52 and the corresponding number are provided. Can be led to the nozzle hole 48 of the nozzle body 36 through the respective pores 52, and the flow of the rubber material is deteriorated in the vicinity of the frictional heating element 38 of the recess 44 in the nozzle body 36. It is good that rubber material stays in It is possible to stop.

  Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention can be configured in various forms without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Rubber injection molding machine 16 Mold 24 Injection cylinder 26 Injection chamber 30 Injection nozzle 36 Nozzle body 38 Friction heating element 44 Recess 48 Nozzle hole 50 Bottom part 52 Fine hole 54 Guide recessed part

Claims (3)

An injection nozzle of an injection molding machine for injecting a rubber material filled in an injection chamber inside an injection cylinder into a mold from an injection nozzle at the tip of the injection cylinder,
(a) a nozzle body having a recess as a passage space for the rubber material inside and having a nozzle hole having a diameter smaller than that of the recess communicated with the recess; b) Separated from the nozzle body, inserted into the recess of the nozzle body and into the inner peripheral surface of the recess over the entire circumference, and extending in the axial direction. Two or more pores having a diameter smaller than that of the nozzle hole, which is in communication with the nozzle hole and causes the rubber material from the injection chamber to pass through in an axial direction to generate heat by friction, An injection nozzle of an injection molding machine comprising: a frictional heating element having a multi-hole structure that is dispersed in the plurality of fine holes and passes through the fine holes and then led to the nozzle holes. .   2. The frictional heating element according to claim 1, wherein the frictional heating element is provided in contact with a bottom portion on the nozzle hole side of the recess in the nozzle body, and each of the plurality of fine holes is provided on the nozzle hole side. An injection nozzle of an injection molding machine, wherein the injection nozzle has a shape that shifts toward the center in the radial direction of the frictional heating element as it advances forward and converges in the nozzle hole.   The inner peripheral shape of the friction heating element according to any one of claims 1 and 2 is narrowed at a rear end side of the frictional heating element as it advances from the rear end opening opened toward the recess of the nozzle body to the front. A guide recess is formed in a round mortar-like concave shape that is continuous with each of the plurality of pores and collects and guides the rubber material reaching the recess from the injection chamber. An injection nozzle of an injection molding machine, wherein the injection nozzle is provided at a position corresponding to the number and a number corresponding to the position.

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