JP4739801B2 - Injection molding machine and its torpedo - Google Patents

Description

The present invention relates to a torpedo for promoting kneading of a molten resin in an injection molding machine and an injection molding machine incorporating the torpedo, and is particularly suitable for use in a plunger type injection molding machine.

  In the injection molding machine, when the molten resin is not sufficiently kneaded, there is a portion that is not in a plastic state, so that it is difficult to obtain a high-quality molded product. In addition, when the resin is colored using a dye, if the resin is not sufficiently kneaded, a poor-looking pattern may be formed on the molded product.

  In order to solve such a problem, for example, Patent Document 1 incorporates a cylindrical torpedo with a hook inside the injection nozzle, and a flow path of the molten resin is formed in the torpedo from the inside to the outside and from the outside to the inside. What is provided is disclosed. In Patent Document 1, the molten resin is kneaded while passing through the torpedo.

JP 11-34108 A

  In the conventional injection nozzle disclosed in Patent Document 1, since the molten resin passes through a complicated flow path in the torpedo, the kneading effect is improved, but there are places where the backflowed resin stays, Over time, the resin is carbonized and becomes a pollutant, which causes problems such as fouling the molded product. Such a problem appears remarkably in a plunger type injection molding machine that cannot sufficiently knead the molten resin in the heating cylinder as compared with the screw type.

  For this reason, particularly in a plunger type injection molding machine, it is desired to knead the molten resin by some means in the resin passage between the plunger and the injection nozzle.

An object of the present invention is to provide an injection molding machine in which a torpedo incorporated in a heating cylinder is provided with a function of kneading a molten resin and a torpedo having such a function is incorporated in order to meet such a demand. There is.

A first aspect of the present invention is a torpedo for kneading molten resin accommodated in a heating cylinder of an injection molding machine, and a plurality of resin passages arranged in a ring at a predetermined pitch are formed to each other. A plurality of torpedo pieces connected in series; and positioning means for defining a rotational phase of the plurality of torpedo pieces, wherein resin passages respectively formed in the plurality of torpedo pieces span the plurality of torpedo pieces. Each outlet portion of the resin passage having the same configuration and formed in the torpedo piece located on the upstream side, and each of the resin passages formed in the downstream torpedo piece connected to the torpedo piece To the two outlet parts adjacent to the resin passage formed in the torpedo piece located on the upstream side so that the inlet part is displaced from each other, the downstream side of the Is characterized in that one of the inlet portion of the resin passage formed in the speeds pieces are arranged astride.

  In the present invention, the molten resin flowing down the resin passage of the upstream torpedo piece is led to the inlet portions of the two resin passages of the downstream torpedo piece facing each other at the outlet portion thereof. That is, when the molten resin flows down from the resin passage of the upstream torpedo piece to the resin passage of the downstream torpedo piece, the molten resin that has passed through the two adjacent resin passages of the upstream torpedo piece is one of these. Each part flows into one opposing resin passage of the downstream torpedo piece, and kneading is performed here.

In the torpedo of the injection molding machine according to the first aspect of the present invention, the torpedo piece comprises a mandrel part and a plurality of partition wall parts projecting radially from the outer peripheral surface of the mandrel part, or these partition walls It is possible to further include a held portion arranged concentrically with the mandrel portion so as to surround the portion. In this case, a partition wall portion is annularly arranged at a predetermined interval between the held portion and the mandrel portion, and a resin passage that is annularly arranged at a predetermined pitch is defined between the adjacent partition wall portions. It becomes. Further, the torpedo piece may further include a conical portion protruding from one end portion of the mandrel portion, and the tip of the conical portion may be formed by a part of a spherical surface having a predetermined radius of curvature. The outlet portion of the resin passage formed in the torpedo piece is set so that the width dimension along the arrangement direction becomes larger toward the outlet end side, or the inlet portion of the resin passage is arranged along the arrangement direction. The width dimension can be set so as to increase toward the inlet end side.

Position-decided Me means includes a projecting portion projecting from one of the two connecting surfaces of the two torpedo pieces are interconnected, and a fitting hole the projecting portions are formed in the connecting surface of the other to be fitted It may be a thing.

A second aspect of the present invention is an injection molding machine including a torpedo according to the first aspect of the present invention .

  According to the torpedo of the injection molding machine of the present invention, one inlet of the resin passage formed in the downstream torpedo piece with respect to two adjacent outlet portions of the resin passage formed in the torpedo piece located on the upstream side Since the portion is arranged across the stretch, when the molten resin flows from the resin passage formed in the upstream torpedo piece to the resin passage formed in the downstream torpedo piece, one downstream side As a result of the molten resin from the two upstream resin passages being guided to the resin passage, even the plunger type injection molding machine promotes the kneading of the molten resin within the heating cylinder, eliminating problems such as color unevenness. can do. In addition, since the torpedo can be divided into a plurality of torpedo pieces, it is possible to improve workability during disassembly and cleaning in the heating cylinder.

  The width dimension of the outlet portion along the arrangement direction of the resin passage formed in the torpedo piece is set to be larger toward the outlet end side, or the width dimension of the inlet portion along the arrangement direction of the resin passage is set to the inlet end side. When set so large, the flow of the molten resin is more greatly disturbed between the outlet portion of the upstream resin passage and the inlet portion of the downstream resin passage, and the molten resin can be kneaded more efficiently.

Position-decided Me means comprises a projecting portion projecting from one of the two connecting surfaces of the two torpedo pieces are interconnected, and a fitting hole the projecting portions are formed in the connecting surface of the other to be fitted In this case, the two torpedo pieces can be easily and quickly connected and disconnected.

Embodiments of the torpedo of the injection molding machine according to the present invention will be described in detail with reference to FIGS. 1 to 4, but the present invention is not limited to these embodiments, and these may be further combined, or claims. Any change or modification included in the concept of the present invention described in the above is possible, and can naturally be applied to other techniques belonging to the spirit of the present invention.

  FIG. 1 shows a cross-sectional structure of the heating cylinder portion of the injection molding machine in the present embodiment, and FIG. 2 shows an enlarged view of the torpedo portion. FIG. 3 shows the appearance of the torpedo in an exploded state. That is, the injection nozzle 13 is integrally connected to the tip end portion of the heating cylinder 12 whose outer peripheral portion is covered with the band heater 11 via the screw portion 14. The outer peripheral portion of the injection nozzle 13 is covered with a ring heater 15, and heating is performed by controlling on / off of energization to the band heater 11 and the ring heater 15 based on a detection signal from a temperature sensor (not shown). The molten resin interposed in the molten resin passages 16 and 17 formed in the cylinder 12 and the injection nozzle 13 can be heated and kept at a predetermined temperature.

  A torpedo 18 and a pair of guide cylinders 19 and 20 for positioning the torpedo 18 in the heating cylinder 12 are incorporated in the heating cylinder 12 whose base end portion is connected to a jacket (not shown). The torpedo 18 and the pair of guide cylinders 19 and 20 are integrally fixed in the heating cylinder 12 by an injection nozzle 13 screwed into the distal end portion of the heating cylinder 12.

  The torpedo 18 in the present embodiment includes two torpedo pieces 18U and 18D located on the upstream side, that is, the jacket side, and on the downstream side, that is, on the injection nozzle 13 side. The basic structures of these two torpedo pieces 18U and 18D are almost the same, and the upstream side and the downstream side can be used in reverse. Each torpedo piece 18U, 18D is concentric with the mandrel part 21 so as to surround the mandrel part 21, the partition wall part 22 projecting radially from the outer peripheral surface of the mandrel part 21, and the partition wall part 22. And an annular held portion 23 that is in contact with the inner peripheral surface of the heating cylinder 12 and the guide cylinders 19 and 29, and a conical portion 24 that protrudes from one end side of the mandrel portion 21. The tip of the conical portion 24 in the present embodiment is formed by a part of a spherical surface having a predetermined radius of curvature, and consideration is given to reducing the flow resistance of the molten resin passing through this periphery.

  The partition wall portion 22 is annularly arranged at a predetermined interval between the mandrel portion 21 and the held portion 23, and accordingly, resin passages 25 are arranged annularly at a predetermined pitch between the adjacent partition wall portions 22. Defined. A pair of inclined surfaces 26 inclined along the circumferential direction are formed at both ends in the longitudinal direction (left and right direction in FIG. 2) of the partition wall portions 22, and each partition wall portion 22 is formed by the pair of inclined surfaces 26. Both ends of each of them have a knife edge shape. In other words, the width dimension along the circumferential direction of both end portions in the longitudinal direction of the resin passage 25 defined between two partition walls adjacent in the circumferential direction is determined by the inclined surfaces 26 of these partition wall portions 22 so that the opening ends. It is in a state where it is set larger toward the side. In this way, consideration is given to reducing the flow resistance of the molten resin passing through the periphery by forming both ends in the longitudinal direction of the partition wall portion 22 in a knife edge shape.

  Moreover, the end surface of the torpedo pieces 18U, 18D opposite to the conical portion 24 functions as a flat connecting surface 27 to which the other torpedo pieces are connected in close contact. A circular positioning pin 28 protrudes from the connecting surface 27 of one torpedo piece 18U, and a fitting hole 29 into which the positioning pin 28 is fitted is formed in the connecting surface 27 of the other torpedo piece 18D. Yes. The positioning pins 28 and the fitting holes 29 are formed in an offset state at positions deviating from the central axis of the torpedo 18, and the positioning pins 28 and the fitting holes 29 functioning as the positioning means of the present invention have two torpedos. This is the only difference between the pieces 18U and 18D.

  In the present embodiment, the connecting surfaces of the two torpedo pieces 18U and 18D are aligned so that the center axes of the two torpedo pieces 18U and 18D coincide with each other when the positioning pin 28 of the one torpedo piece 18U is fitted in the fitting hole 29 of the other torpedo piece 18D. The positioning pin 28 and the fitting hole 29 are formed so that the resin passage 25 of the other torpedo piece 18D is shifted by a half pitch with respect to the resin passage 25 of the one torpedo piece 18U in a state where the 27 is in close contact. Each position is set.

  It should be noted that the amount of displacement of the resin passage 25 of the other torpedo piece 18D with respect to the resin passage 25 of the one torpedo piece 18U is not limited to a half pitch and can be arbitrarily selected.

  Accordingly, the molten resin pressurized by a plunger (not shown) is guided into the resin passage 25 of the torpedo piece 18U located upstream from the molten resin passage 16 of the heating cylinder 12, and faces the outlet portion of the resin passage 25. The two resin passages 25 of the torpedo piece 18D located on the downstream side are distributed to the two resin passages 25 to promote kneading, and from the molten resin passage 17 of the injection nozzle 13 to a mold (not shown). It is injected. That is, the molten resin flowing down the resin passage 25 of the upstream torpedo piece 18U is led to the inlet portions of the two resin passages 25 of the downstream torpedo piece 18D facing each other at the outlet portion, and the upstream side Part of the molten resin that has passed through two adjacent resin passages 25 of the torpedo piece 18U flows into one opposing resin passage 25 of the downstream torpedo piece 18D, where kneading is performed.

  In the above-described embodiment, the torpedo 18 is formed by the two torpedo pieces 18U and 18D, but a torpedo formed by connecting one or more torpedo pieces between the two torpedo pieces 18U and 18D is adopted. Is also possible.

  The appearance of another embodiment of such a torpedo is shown in a broken state in FIG. 4, but the same reference numerals are used for elements having the same functions as those of the previous embodiment, and duplicate descriptions are omitted. . That is, a torpedo piece 18C having no conical part is interposed between two torpedo pieces 18U and 18D each having a conical part 24. The torpedo piece 18C has substantially the same configuration as the previous torpedo pieces 18U and 18D except that it does not have a conical portion, but a fitting hole (not shown) is formed on a connecting surface (not shown) on one end side in the longitudinal direction. Similarly, a positioning pin (not shown) projects from the connecting surface on the other end side. When these positioning means are used to integrally connect the three torpedo pieces 18U, 18C, and 18D so that the central axes thereof coincide with each other, the resin passage 25 of the torpedo piece 18C located at the center portion thereof The resin passages 25 of the two torpedo pieces 18U and 18D located on both sides are shifted by, for example, a half pitch.

  Therefore, by using the torpedo 18 according to this embodiment, the molten resin is kneaded by the resin passage 25 formed in the central torpedo piece 18C and the resin passage 25 formed in the downstream torpedo pieces 18U and 18D. Can be performed twice, and a better kneading result than in the previous embodiment can be obtained.

It is sectional drawing represented in the state which partially fractured one Embodiment of the torpedo of the injection molding machine by this invention. It is sectional drawing of the part of the torpedo shown in FIG. FIG. 2 is a three-dimensional projection view showing the torpedo shown in FIG. It is a three-dimensional projection figure showing the external appearance of other embodiment of the torpedo of the injection molding machine by this invention in a partially broken state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Band heater 12 Heating cylinder 13 Injection nozzle 14 Screw part 15 Ring heater 16, 17 Molten resin passage 18 Torpede 19, 20 Guide cylinder 18U, 18C, 18D Torpedo piece 21 Core part 22 Partition wall part 23 Hold part 24 Conical part 25 Resin passage 26 Inclined surface 27 Connecting surface 28 Positioning pin 29 Fitting hole

Claims (8)

It is a torpedo for kneading a molten resin accommodated in a heating cylinder of an injection molding machine,
A plurality of torpedo pieces each having a plurality of resin passages arranged annularly at a predetermined pitch and connected in series with each other, and positioning means for defining rotational phases of the plurality of torpedo pieces ,
Wherein the plurality of torpedo pieces resin passage formed each having a respective identical configuration over a corresponding plurality of torpedo pieces, and individual outlet portion of the resin passage formed in the torpedo piece located upstream, Two adjacent resin passages formed in the upstream torpedo piece so that the respective inlet portions of the resin passages formed in the downstream torpedo piece connected to the torpedo piece are displaced from each other. A torpedo for an injection molding machine, characterized in that one inlet portion of a resin passage formed in the torpedo piece on the downstream side of the two outlet portions is disposed across the outlet portion.   2. The torpedo for an injection molding machine according to claim 1, wherein the torpedo piece includes a mandrel part and a plurality of partition walls projecting radially from an outer peripheral surface of the mandrel part.   The torpedo piece further includes a held portion arranged concentrically with the mandrel portion so as to surround the partition wall portion, and the partition wall portion has a predetermined interval between the held portion and the mandrel portion. 3. The torpedo of an injection molding machine according to claim 2, wherein the resin passages are annularly arranged, and the resin passages are annularly arranged at a predetermined pitch between the adjacent partition wall portions.   4. The torpedo for an injection molding machine according to claim 2, wherein the torpedo piece further comprises a conical portion protruding from one end portion of the mandrel portion.   5. The torpedo for an injection molding machine according to claim 4, wherein the tip of the torpedo piece is formed by a part of a spherical surface having a predetermined curvature radius at the tip of the conical portion.   The outlet portion of the resin passage formed in the torpedo piece is set such that the width dimension along the arrangement direction is larger toward the outlet end side, and the inlet portion of the resin passage has the width dimension along the arrangement direction. The torpedo for an injection molding machine according to any one of claims 1 to 5, wherein the torpedo is set larger toward the inlet end side. The positioning means has a protrusion protruding from one of the two connection surfaces of the two torpedo pieces connected to each other, and a fitting hole formed in the other connection surface into which the protrusion fits. The torpedo for an injection molding machine according to any one of claims 1 to 6, wherein the torpedo is used.   An injection molding machine comprising the torpedo according to any one of claims 1 to 7.

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