JP4172713B2 - Preform molding equipment for resin molding - Google Patents

Description

  The present invention relates to a resin molding machine and is an apparatus that can perform a series of processes from injection molding to stretch blow molding, and molds a preform whose temperature is controlled to suit before stretch blow molding. It is related with the apparatus which performs.

  In the resin molding technique, when a blow molded product is finally produced, a technique is known in which a preform is first molded by injection molding and stretch blow molded in order to increase molding accuracy. The applicant has also developed and filed a device for achieving this series of techniques.

JP 2004-276527 A JP 04-027520

  Among these, the invention method described in Patent Document 2 improves the conventional four-station method that requires four steps of “injection molding of preform—temperature adjustment—stretch blow molding—removal of molded product” and omits temperature adjustment. It is assumed that a three-station system will be used. Further, the invention apparatus described in Patent Document 1 is not described as adjusting the temperature of the preform, so it can be said that the apparatus basically employs a three-station system.

  By the way, when a preform is manufactured by injection molding, and this is transferred to a stretch blow process and stretch blow molding is performed, temperature control of the preform is very important. In other words, if the surface temperature of the preform partially varies or a temperature deviation appears regardless of the thickness of the preform, the product that has undergone the subsequent stretch blow process cannot guarantee high quality. .

  In general, the outline of injection molding is as shown in FIG. 6, in a state where the inner core 62 is fitted in the injection cavity 61, and the resin flow path 66 in which the molten resin is provided in the manifold 65 by the injection cylinder 64 through the gate 63. A cooling water circuit (not shown) is provided in the injection cavity 61 in order to cool the molten resin. Then, by injecting the molten resin into the cooled injection cavity 61, the surface of the molten resin is cooled to form a skin layer, and a preform in which the inside is molten is completed. However, when the preform is molded using only this apparatus, the temperature of the cooling water is increased from the upstream side to the downstream side, and thus a temperature gradient is generated in the surface temperature of the preform according to the flow path. If so, there may be no problem depending on the shape of the preform, but on the contrary, there may be a case where the stretch blow molding with high accuracy cannot be performed due to the temperature deviation.

  An object of the present invention is to solve such a problem, and eliminates the temperature deviation of the surface temperature of the preform, which is inevitable in the configuration of the apparatus, and performs more appropriate temperature management. A technique capable of forming a preform is disclosed.

  In the present invention, in order to achieve the above object, the preform formed in the injection molding machine is transferred to the blow molding machine and employed in a resin molding machine that performs blow molding. The blow molding machine includes one that performs a stretching process prior to blow molding. And after taking out the injection-molded preform from the injection mold, it has a space for accommodating the preform inside and is divided into a plurality of planes perpendicular to the axis of the preform, and the temperature control pot can be opened and closed freely. A means of raising the surface temperature of the preform was adopted. According to this means, even if an undesirable temperature deviation occurs in the surface temperature of the preform due to cooling performed to form a skin layer on the preform during injection molding, the surface temperature is forcibly increased by the temperature control pot. Therefore, the surface temperature is made uniform or an intentional temperature deviation is given.

  The temperature control pot is composed of a semi-cylindrical upper temperature control pot and a lower temperature control pot obtained by further dividing the semi-cylinder into two parts, and the two lower temperature control pots are spread outward by a link mechanism. The means of forming a reforming storage port was used. More specifically, the two lower temperature control pots are connected in the vicinity of the diameter of the upper temperature control pot where the arc intersects with the diameter, and the two lower temperature control pots are expanded while rotating outwardly around the connection point. It was. With this means, the temperature control pot can be opened and closed by a simple link mechanism, and the preform can be easily stored and taken out.

  Furthermore, a means of providing a gate cut blade for cutting the gate piece in the vicinity of the intersection of the two radii on at least one of the lower temperature control pots was used. With this means, the gate piece inevitably generated in the preform as the lower temperature control pot is opened and closed can be cut, and a separate device is not required.

  Since the present invention employs the above-described means, immediately after taking out the preform manufactured by injection molding from the injection cavity, the temperature of the preform is adjusted to an appropriate temperature by a temperature control pot, and at the same time removed from the mold. In the preform, a gate piece that is inevitably generated at a position corresponding to the gate portion can be cut. Therefore, the temperature of the preform can be adjusted while cutting the gate piece, so that it is possible to manufacture a highly accurate molded product while avoiding a significant time loss.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. 1 to 3 show an example of a resin molding machine to which the apparatus of the present invention is applied. Basically, a new apparatus is incorporated in the molding machine described in Patent Document 1 related to the applicant. Is. The molding machine as a whole shows a series of cycle processes in which the molding process proceeds from FIG. 1 to FIG. 3 and returns from FIG. 3 to FIG. Here, A represents an injection molding block in the apparatus of the present invention, and B represents a blow molding block. Reference numeral 1 denotes a fixed side of the apparatus, and reference numeral 2 denotes a moving side. The moving side 2 performs a reciprocating motion so that a series of steps from injection molding to blow molding is continuously performed.

  As the configuration of the fixed side 1, 3 is a hot runner adopting a known structure, 4 is a nozzle for introducing a molten resin such as PET into the runner 3 and 5 is for injecting the molten resin into a mold. A gate, 6 is a female mold, 7 is a mouth mold for placing a preformed preform (preform) on the female mold 6 side, or for undercutting the molded product, 8 It is a fixed side plate storing the female mold 6. Here, as is apparent from the drawings, in the apparatus of the present invention, the female die 6 and the mouth portion die 7 are not assembled from the nozzle 4 side, but the hot runner 3 is left as it is from the moving side 2 to the female die 6 and the mouth portion. The mold 7 is assembled in the order. Reference numeral 9 denotes a gate cutting machine for cutting gate pieces remaining in the gate portion of the preform. And in this invention, although the important improvement is added to the gate cut machine 9, this point is mentioned later.

Next, the structure of the moving side 2 will be described. 10 is a male mold for injection molding a preform,
Reference numeral 11 denotes a moving side plate on which the male mold 10 is provided. Then, the moving side 2 repeats reciprocating movement with respect to the fixed side 1, and the molten resin introduced from the nozzle 4 in a state in which the male die 10 is securely accommodated in the female die 6 is passed through the gate 5 by the hot runner 3. By being injected, preforms are sequentially manufactured, and unnecessary gate pieces are cut out by the gate cutting machine 9. As described above, the injection molding of the preform is performed in accordance with the reciprocation of the moving side 2 with respect to the fixed side 1.

  Subsequently, a configuration in which a preform manufactured by the above-described procedure is conveyed and a final product is manufactured by blow molding will be described. In the figure, reference numeral 12 denotes a preform transfer arm. When this transfer arm rotates by a predetermined angle, the preform receiving core 13 installed at the tip thereof receives the preform from the injection mold, and the blow molding machine receives the preform. Transport. As for the blow molding block B, one side 14 of the split hollow molds 14 and 15 is provided on the fixed side 1 and the other side 15 is provided on the moving side 2. Are arranged so as to be combined as a molding die at the same time as they are in close contact with the fixed side 1. FIG. 1 shows the case where the transfer arm 12 moves downward and the preform receiving core 13 is located on the blow molding block B side, and FIG. 2 is the opposite, FIG. 2 shows the preform receiving core 13 on the injection molding block A side. The case where it is located is shown. In the present embodiment, the transfer arm 12 is configured to deliver the preform by rotating 90 degrees downward from the horizontal direction, but the rotation angle is not limited. Reference numeral 16 denotes a nest of the preform receiving core 13, which prevents the preform received by the preform receiving core 13 from dropping during transfer by applying vacuum. Note that this configuration is an example, and it is also within the scope of the present invention to adopt a configuration in which the insert 16 is prevented from falling off by mechanical contact with the preform or a configuration in which falling off is prevented by light adhesion. included.

  Reference numeral 17 denotes an extending rod, and 18 denotes an extending rod tip, which is configured to be inserted into a forming die and blown air at the time of blow molding. In addition, the extending | stretching rod front-end | tip tip 18 can be removed and replaced | exchanged, and a dissimilar molded product can be shape | molded by exchanging this.

  Reference numeral 19 denotes a bottom mold mounting plate, and a bottom mold 20 for blow molding is provided on the top thereof. The bottom mold mounting plate 19 is supported by a bottom mold mounting presser plate 21 in a state where the moving side 2 is closed. The bottom mold mounting presser plate 21 branches and applies pressurized air used at the time of injection molding. Thus, the bottom mold mounting plate 19 is biased upward so that the bottom mold 20 does not move even during blow molding. The bottom mold mounting plate 19 may be structured to move in the horizontal direction or the rotation direction when the support of the bottom mold mounting presser plate 21 is removed, so that the final molded product can be easily taken out.

  In such a configuration, a series of steps from injection molding to blow molding will be described. First, the fixed mold 1 and the movable mold 2 are combined, and the male mold 10 is fitted to the female mold 6 to provide the hot runner system 3 and the like. Install the injection molding machine. Then, an arbitrarily selected resin such as molten PET resin, polyethylene resin, or polypropylene resin is injected into the nozzle 4. Subsequently, the moving side 2 is moved in the direction of arrow C to expand the mold. In this embodiment, the shape of the mouth mold 7 is set so that at least some undercut occurs. By doing so, it is possible to prevent the preform from coming into close contact with the male mold 10 and moving to the female mold 6 when the mold is opened, and to ensure the subsequent steps. In this way, the injection molding process is completed. During the injection molding process, the arm 12 is positioned so as to face vertically downward, and the preform receiving core 13 is positioned on the blow molding block B side.

  Subsequent to the injection molding process, a preform transfer process is started. As the mold is opened, the arm 12 rotates in the direction of arrow D to reach the state shown in FIG. 2, and then the mouth mold 7 advances toward the preform receiving core 13 while holding the preform. A preform receiving core 13 is provided at the tip of the arm 12. Since this core has the same shape as the male mold 10, the preform receiving core 13 is covered with the preform. At this time, the mouth mold 7 is divided into two parts in the direction of arrow E in FIG. 3 and expands, and even when an undercut or the like is provided, the part does not interfere. Then, the mouth mold 7 moves backward and returns to the state shown in FIG. 1, but the preform moves to the receiving core 13 side because vacuum or the like is working in the insert 16 provided in the receiving core 13. Subsequently, the gate piece is cut by the gate cutting machine 9 attached to the fixed side 1. Then, the arm 12 rotates in the return direction (the direction opposite to the arrow C) to transfer the preform to the blow molding block B. In order to prevent the preform from being damaged, the centers of the preform receiving core 13 and the mouth mold 7 need to be coincident. Although not shown, it goes without saying that the male mold 10 and the arm 12 or the preform receiving core 13 are offset so as not to interfere with the rotation.

  After being transferred to the blow molding block B, the moving side 2 moves in the mold closing direction, and the drawing rod 17 installed on the moving side 2 passes through the inside of the moving side plate 11 while drawing the preform. Compressed air is blown from the tip 18 side of this to perform stretched hollow molding. In the injection molding block A, the preform injection molding process is in progress at the same time.

  In the blow molding process, since the bottom mold mounting plate 19 is supported by the pressurized air branched from the bottom mold mounting presser plate 21 as described above, the molding mold such as the bottom mold 20 is not displaced in the molding process. Absent. When the mold clamping of the injection molding machine is changed from high pressure to low pressure, the hollow molds 14 and 15 move downward with the mold closed to release the interference with the insert 16 and prevent damage to the molded product. I am doing so. In this case, the suction by the vacuum in the insert 16 is stopped.

  As a final process, a process for taking out a molded product will be described. When the moving side 2 is expanded again as shown in FIG. 2 or FIG. 3, the bottom mold 20 in the blow molding block B is provided on the fixed side 1, so that the molded product is placed on the bottom mold 20 in the fixed side. 1 remains. From this state, the molded product is dropped onto an appropriate conveyor (not shown) or the like by its own weight by rotating or translating the bottom mold mounting plate 19 and transporting it outside the apparatus. Note that the molded product can be taken out by a known molded product take-out machine or the like instead of being dropped onto the conveyor.

  Next, details of the gate cutting machine 9 will be described. 4 is a side view of the gate cutting machine as seen from the direction shown in FIG. 1, and FIG. 5 is a front view. The gate cut machine of the present invention is specifically configured by combining a gate cut and a temperature control device. In the figure, 31 is a front / rear cylinder for moving the entire apparatus back and forth, and 32 is an upper / lower cylinder for moving the entire apparatus up and down. These cylinders move the apparatus to a predetermined position. Reference numeral 33 denotes a base that moves up and down in accordance with the movement of the upper and lower cylinders 32. The base 33 is provided with a semi-cylindrical upper side temperature control pot 34 that protrudes, and is divided into four parts with a 90-degree section fan. In a state where the side temperature control pots 35 and 36 are combined with the upper side temperature control pot 34, the preform P is held in the space inside. The two lower side temperature control pots 35 and 36 are hinge-connected in the vicinity where the diameter of the upper side temperature control pot 34 intersects with the arc of the upper side temperature control pot 34, and at the same time connected to a semicircular arc-shaped link 37. The link 37 is moved up and down by a link control cylinder 38.

According to this configuration, the preform P taken out from the female mold 6 is left in the preform receiving mold 13, but once positioned in this state, the preform P is moved by the movement of the front and rear cylinders 31 and 32. Housed in the upper temperature control pot 34. At this time, the lower temperature control pots 35 and 36 are opened by the operation of the link 37. When the preform P is accommodated in the upper temperature control pot 34, the link control cylinder 38 is pulled up and the lower temperature control pots 35 and 36 are closed by the operation of the link 37. Either one of the lower side temperature control pots 35 and 36 is provided with a gate cut blade 39 near the sector radius intersection. If the lower side temperature control pots 35 and 36 are closed, the lower side opposite to the gate cut blade 39 is provided. Cut the excess gate piece by the edge of the temperature control pot. The cut small pieces are collected by the vacuum through the small piece collecting pipe 40 so that the waste is not scattered. The gate cut blade 39 is provided in one lower temperature control pot 35 and cuts the gate piece in a so-called push-cut form. However, as another modified example, the blade is provided on both sides to cut by the scissors method. It is also possible. Although the shape of the temperature control pot is cylindrical in this embodiment, the shape is limited to a cylindrical shape because it has an essential function of raising the temperature by holding the preform from the entire periphery. It is not essential to adopt a shape corresponding to the shape of the preform. Therefore, the shape is not limited to a cylinder.

Next, temperature adjustment of the temperature adjustment pot will be described. In the figure, reference numeral 41 denotes a temperature adjustment rubber heater, which is provided on the inner periphery of the cylindrical space. And the whole is adjusted to predetermined temperature by controlling the electric power supply with respect to this heater. As temperature conditions assumed by the inventors, for example, in the case of polypropylene resin molding, the molten resin temperature is 225 ° C., the in-mold resin temperature is 235 ° C., and the temperature control temperature for mold cooling is 50 to 55 ° C. The surface temperature of the reform is about 80 to 105 ° C. In the case of PET resin molding, when the molten resin temperature is 280 to 290 ° C., the in-mold resin temperature is 295 ° C., and the cooling water temperature is 15 ° C., the surface temperature of the preform is about 110 to 120 ° C. It was confirmed. Then, it was verified that the precision of the subsequent stretch blow molding is improved by raising the temperature of these preforms to about 140 ° C. using a temperature control pot. Here, the temperature disclosed in the description is only a guide, and the present invention does not strictly limit the temperature condition. A necessary condition in terms of temperature is to raise the surface temperature of the preform obtained by injection molding using a temperature control pot, and the temperature condition is not particularly limited as long as this can be achieved. Therefore, if a temperature deviation is intentionally given to the temperature of the rubber heater 41 of the temperature control pot, it is possible to cause an intentional temperature deviation even with respect to the surface temperature of the preform, and this is eliminated. It is not a thing. In the present embodiment, the temperature of the temperature control pot is managed by the rubber heater 41. However, the temperature raising means is not limited to this, and any known heater can be used except those that are not mechanically applicable. It is possible to adopt the same as a rubber heater.

Schematic showing an example of a resin molding machine to which the present invention is applied Schematic diagram showing the operation during the process Schematic showing the operation on the way Side view showing details of gate cut machine Same front view Schematic showing the general process of injection molding

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed side 2 Moving side 3 Hot runner 4 Nozzle 5 Gate 6 Female type | mold 7 Mouth part type | mold 8 Fixed side plate 9 Gate cut machine 10 Male type | mold 11 Moving side plate 12 Transfer arm 13 Receiving core 14 * 15 Hollow type | mold 16 Entry 17 Extension rod 18 Extension rod tip 19 Bottom mold mounting plate 20 Bottom mold 21 Bottom mold mounting presser plate 31 Front and rear cylinders 32 Upper and lower cylinders 33 Base 34 Upper side temperature control pots 35 and 36 Lower side temperature control pots 37 Link 38 Link control cylinder 39 Gate cut Blade 40 Small piece recovery pipe 61 Injection cavity 62 Inner core 63 Gate 64 Injection cylinder 65 Manifold 66 Resin flow path

Claims (5)

In a resin molding machine that performs blow molding by transferring a preform molded in an injection molding machine to a blow molding machine, a space for accommodating the preform inside after the injection molded preform is taken out from an injection mold The temperature control pot is divided into a plurality of parts on a plane perpendicular to the axis of the preform and can be freely opened and closed . This temperature control pot is composed of a semi-cylindrical upper temperature control pot and a lower part obtained by further dividing the half cylinder into two parts. Resin characterized in that it consists of temperature control pots, and the two lower temperature control pots are each expanded outward by a link mechanism to form a preform receiving port, and the surface temperature of the preform is raised. Preform molding equipment for molding.   2. The preform molding in the resin molding according to claim 1, wherein the two lower temperature control pots are connected in the vicinity of the diameter of the upper temperature control pot where the arc intersects with the diameter, and are expanded outwardly about the connection point. apparatus.   The preform molding apparatus for resin molding according to claim 1 or 2, wherein a gate cut blade for cutting a gate piece is provided in the vicinity of an intersection of two radii on at least one of the lower temperature control pots.   2. The preform molding apparatus for resin molding according to claim 1, wherein the temperature control pot is moved back and forth and up and down by a front and rear cylinder and an upper and lower cylinder.   2. The preform molding apparatus for resin molding according to claim 1, wherein the blow molding machine is a molding machine provided with a stretching process performed immediately before blow molding.

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