JP2016007720A - Die head and molding machine provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, when a part in the longitudinal direction of a parison is made into a different color, in the conventional die head, in a ring piston and a material reservoir, each requires to be provided with resin passages with different colors, and further, there requires a hydraulic cylinder in each ring piston, the constitution is complicated.SOLUTION: The main annular passage 27 to be continuously fed with the main resin material is formed between the inter mandrel 25 of a die head 4 and a die 22. A sub-annular passage 28 intermittently fed with a colored sub-resin material is formed between the outer mandrel 24 and a head body 21. An annular slide valve 31 is arranged at the sub-annular passage 28 slidably by a prescribed amount. When the sub-resin material is not fed, a seal face 31c at the upper edge shuts the sub-annular passage 28. When the sub-resin material is fed via a gear pump, the slide valve 31 is opened, and the outer circumferential face of the parison is provided with a colored layer.

Description

  The present invention relates to an improvement of a die head for extruding a parison in a hollow molding machine, and more particularly, to a die head and a molding machine that can overlap, for example, resin materials having different colors on a part of the longitudinal surface of the parison. .

  The hollow molding machine uses a pair of molds to hold a cylindrical parison extruded in a vertical direction from the die head, and then blows air into the parison at an air driving stage provided adjacent to the die head. Thus, the parison is pressed against the inner surface of the mold cavity to obtain a hollow resin molded product.

  In such a hollow molding machine, various multilayering techniques for constructing a parison (and thus a resin molded product) from a plurality of resin material layers have already been proposed and put into practical use.

  In Patent Document 1, a plurality of cylindrical ring pistons are arranged in the extruding portion of the parison, and each ring piston extrudes a resin material in a cylindrical material reservoir by the action of a hydraulic cylinder, whereby the parison is multilayered. A technique for realizing the above is disclosed.

Japanese Patent Publication No.57-53175

  For example, in the case where a part of the longitudinal direction of the resin molded product has a different color, a second resin material having a color different from that of the main first resin material is applied during the parison extrusion by the first resin material. Although it is necessary to add to the parison surface, since the ring piston and the material reservoir are provided in the resin passages of different colors and a hydraulic cylinder is required for each ring piston, the configuration is complicated.

The die head according to the present invention is:
A die and a core constituting a main annular flow path to which a main resin material is continuously supplied;
An outer peripheral side cylindrical member and an inner peripheral side cylindrical member configured to join the auxiliary annular flow path to which the secondary resin material is intermittently supplied to the outer peripheral portion of the main annular flow path;
The sub-ring is slidable by a predetermined amount in the sub-annular flow path, the pressure of the sub-resin material acts in the downward direction, the pressure of the main resin material acts in the upward direction, and seals according to the vertical sliding An annular slide valve whose surface opens and closes the auxiliary annular channel;
It is configured with.

  The main resin material is continuously supplied to the main annular flow path in a plasticized state using, for example, an extruder, and is extruded as a cylindrical parison from the die and core outlets. The sub resin material is made of a resin material different from the main resin material, for example, a resin material colored in a color different from that of the main resin material. For example, the sub resin material is intermittently supplied to the sub annular flow path in a plasticized state using an extruder. Is done. That is, it is temporarily supplied in a part of the molding cycle so as to overlap with a part of the longitudinal surface of the parison extruded continuously from the die head.

  In a state where the secondary resin material is not supplied, the slide valve is moved upward under the pressure of the primary resin material, and closes the secondary annular flow path. When the sub resin material is supplied, the slide valve receives the pressure of the sub resin material and moves downward to open the sub annular channel. Thereby, it is extruded as a two-layer parison so that the sub-resin material forms a layer on the main resin material layer. When the supply of the sub resin material is stopped, the slide valve rises again under the pressure of the main resin material and closes the sub annular channel as the pressure of the sub resin material decreases.

  In this way, since the secondary annular channel is opened and closed all at once by the slide valve, the position of the boundary between the main resin material and the secondary resin material appearing on the surface becomes more uniform over the entire circumference. .

  In a specific embodiment, the seal surface is formed at the upper end of the slide valve as an inclined surface that abuts against the inclined seating surface of the inner circumferential cylindrical member or the outer circumferential cylindrical member, A stopper portion is provided on the outer peripheral surface of the slide valve so as to protrude from the outer peripheral side cylindrical member or the inner peripheral side cylindrical member so as to define a lower limit position of the slide valve. Therefore, in a state where the slide valve opens the secondary annular flow path, the secondary resin material flows smoothly along the inclined seal surface and seat surface, and the inner peripheral surface of the slide valve and the inner peripheral side cylindrical member Or between the outer peripheral surface of the slide valve and the outer cylindrical member is a substantial flow path.

  In a preferred embodiment, a gear pump capable of transporting the material in both forward and reverse directions is added to the secondary resin material supply path between the secondary resin material extruder and the secondary annular flow path. By using such a gear pump, it is possible to realize a slide valve responsive opening operation due to a rapid pressure increase, and a positive pressure drop in the sub-annular flow path due to reverse rotation, and thus a slide valve responsive closing operation. Can be realized.

  Further, the main annular channel and the sub-annular channel join at a position immediately before the die. If the flow path of the main annular passage is long in the annular passage after the confluence of the main annular passage and the sub annular passage, both of the parisons after the confluence are caused by the difference in the flow velocity of the main and sub annular passages. Since the boundary of the flow path becomes unclear, it is desirable to join at a position as close to the downstream side as possible, that is, as close as possible to the die outlet, and it is most desirable to join at a position immediately before the die.

  Furthermore, a novel molding machine provided with the above-described problem solving means is configured.

  According to the present invention, since the sub-annular flow path is opened and closed by the slide valve that slides up and down in the sub-annular flow path, the boundary of the layer of the sub resin material provided on the partial surface in the longitudinal direction of the parison is formed. , A more uniform position can be obtained over the entire circumference. Therefore, for example, when a colored resin layer is provided on a part of the resin molded product in the longitudinal direction, the quality is improved.

The side view which shows one Example of the hollow molding machine which concerns on this invention. The front view of a hollow molding machine. The expanded sectional view of the die head of this hollow molding machine. The expanded sectional view in the state where the slide valve has closed the sub annular channel. The perspective view of a slide valve. The partial cross section figure of a slide valve. Explanatory drawing of a gear pump. Explanatory drawing of the extrusion process of Parison. The time chart which shows operation | movement of the extruder and gear pump in 1 molding cycle. The figure which shows the shape | molded container.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 and FIG. 2 are a side view and a front view showing the entire configuration of a hollow molding machine provided with an extrusion structure according to the present invention. The hollow molding machine includes a main extruder 3 supported on a base 1 so as to swing up and down via a support shaft 2, an extrusion head 4 attached to the tip of the main extruder 3, A sub-extruder 5 disposed in front of the extrusion head 4 in the vertical direction, an air driving device 6 (see FIG. 2) provided side by side on the extrusion head 4, and a pair of halves The mold 7 is roughly constituted by a mold clamping device 8 that clamps the mold 7 and reciprocates between a position below the extrusion head 4 and a position below the air driving device 6.

  The main extruder 3 incorporates a screw (not shown) that is rotated by a drive motor 11, and kneads and plasticizes the main resin material introduced from the hopper 12 and continuously supplies it to the extrusion head 4. The main extruder 3 supported so as to be swingable via the support shaft 2 is the same as the extrusion head 4 at the moment when the mold clamping device 8 sandwiches the parison continuously extruded in the vertical direction from the extrusion head 4. It is comprised so that it may raise a little with it.

  The sub-extruder 5 is supported integrally with the extrusion head 4 so as to swing up and down together with the main extruder 3 and the extrusion head 4. The sub-extruder 5 incorporates a screw (not shown) that is rotated by a drive motor 13, and kneads and plasticizes the sub-resin material introduced from the hopper 14 and supplies it to the extrusion head 4. As the auxiliary resin material, in this embodiment, a colored resin material colored in a predetermined color is used with respect to the main resin material which is not colored. The extrusion of the auxiliary resin material by the auxiliary extruder 5 is performed only for a certain period in one molding cycle, as will be described later, and the parison and eventually the one in the longitudinal direction of the final resin molded product 15 (see FIG. 1). A colored layer is provided only on the surface of the portion.

  A gear pump 16 capable of transporting a plastic material in both forward and reverse directions is added between the sub-extruder 5 and the die head 4, and a drive motor 17 for the gear pump 16 is supported by the sub-extruder 5. ing. The gear pump 16 is provided with a pressure sensor 18 that detects the pressure of the secondary resin material on the upstream side of the gear pump 16 (that is, the discharge portion of the secondary extruder 5).

  As will be described later, the die head 4 continuously extrudes a cylindrical parison using a main resin material and a sub resin material, and includes an electric motor 19 for adjusting the thickness of the parison at the upper end. ing.

  FIG. 3 is a half cross-sectional view showing details of the extruded portion at the lower end of the die head 4. A disk-shaped die 22 is attached to the lower end of a cylindrical head body 21 supported at the tip of the main extruder 3 via a retainer 23. On the inner peripheral side of the head body 21, a substantially cylindrical outer mandrel 24 and a substantially cylindrical inner mandrel 25 positioned on the inner peripheral side are provided so as to be concentric with the head body 21. Yes. The outer mandrel 24 and the inner mandrel 25 are supported integrally with the head body 21 at an upper portion (not shown) and are in a fixed position with respect to the head body 21. A core shaft 26 is fitted on the inner peripheral side of the inner mandrel 25 so as to be vertically slidable. The lower end portion of the core mandrel 25 and the die 22 form a discharge port 30 made of a parison in an annular shape. Yes.

  The space between the inner mandrel 25 and the die 22 and the space between the inner mandrel 25 and the outer mandrel 24 are supplied with a main annular channel 27 to which the main resin material plasticized by the main extruder 3 is supplied. The lower end of the discharge port 30 is open. The main annular flow passage 27 communicates with the discharge portion of the main extruder 3 at the upper portion (not shown). A space between the outer mandrel 24 and the inner peripheral surface 21a of the head body 21 is a sub-annular passage 28 to which a sub-resin material plasticized by the sub-extruder 5 is supplied. The sub-annular flow path 28 communicates with the discharge side of the gear pump 16 at an upper portion (not shown). The downstream side of the sub-annular flow path 28 merges with the outer peripheral portion of the main annular flow path 27 at a merge section 29 that is a position immediately before the die 22. That is, the lower end 24 a of the outer mandrel 24 extends to a position relatively close to the die 22, and forms a merge portion 29 with the smoothly curved shoulder portion 21 b on the inner periphery of the head body 21.

  An annular slide valve 31 is accommodated at a position upstream of the joining portion 29 of the sub annular channel 28. As shown in FIGS. 5 and 6, the slide valve 31 has a short cylindrical shape, and includes an outer peripheral surface 31 a slidably contacting the inner peripheral surface 21 a of the head body 21 and an outer peripheral surface of the outer mandrel 24. An inner peripheral surface 31b that constitutes a flow path 28a that forms a part of the sub-annular flow path 28, a seal surface 31c that is inclined inside the upper end, and a pressure receiving surface 31d that is gently curved at the lower end are provided. In addition, a stopper portion 32 that protrudes to the outer peripheral side in a rectangular cross section is formed on the entire outer peripheral surface.

  Corresponding to the sealing surface 31c of the slide valve 31, the outer mandrel 24 is formed with a seat portion 33 swelled in a mountain shape on the outer peripheral surface, and the lower end seating surface 33a is formed on the sealing surface 31c. It has a corresponding inclined surface. As shown in FIG. 4, at the position where the slide valve 31 slides upward, the seal surface 31 c comes into contact with the seat surface 33 a of the outer mandrel 24 and closes the auxiliary annular flow path 28. Further, as shown in FIG. 3, at the position where the slide valve 31 slides downward, the seal surface 31c is separated from the seat surface 33a, and the auxiliary annular flow path 28 is opened via the flow path 28b generated between the both.

  The stopper portion 32 is slidably engaged in an annular groove 34 formed on the inner peripheral surface 21 a of the head body 21. As shown in FIG. 3, when the slide valve 31 moves downward, the stopper portion 32 engages with the lower end 34a of the concave groove 34, whereby the lower limit position of the slide valve 31 is defined, and the seal surface 31c and the seat surface A flow path 28b having a predetermined interval is secured between the terminal 33a and 33a. When the slide valve 31 moves upward, the stopper portion 32 does not contact the upper end of the concave groove 34, and the upper limit position of the slide valve 31 is defined by the contact between the seal surface 31c and the seat surface 33a.

  In the above embodiment, the head body 21 corresponds to the “outer peripheral side cylindrical member”, and the outer mandrel 24 corresponds to the “inner peripheral side cylindrical member”. In the illustrated example, the head body 21 is divided into a plurality of members in the vertical direction for the convenience of processing the concave groove 34 and the shoulder portion 21b.

  Further, in the above embodiment, the seat surface 33a of the outer mandrel 24 is provided in a portion corresponding to the head body 21, and the seal surface corresponding to this seat surface is a slide valve having a structure opposite to that of the slide valve 31. In addition, a stopper portion corresponding to the stopper portion 32 can be provided on the slide valve, and a concave groove corresponding to the concave groove 34 can be provided on the outer mandrel 24 to provide the same function as described above.

  FIG. 7 shows a gear pump 16 provided between the sub-extruder 5 and the extrusion head 4. The gear pump 16 is, for example, an external gear type gear pump, and includes a pump base 35 in which a suction-side flow path 36 and a discharge-side flow path 37 are formed, and a gear case 38 having a built-in gear mechanism. ing. The suction side flow path 36 is connected to the discharge portion of the sub-extruder 5, and the discharge side flow path 37 is connected to the upper part of the sub annular flow path 28 of the extrusion head 4. The gear pump 16 does not include a check valve, and can transport the secondary resin material in both forward and reverse directions as the gear mechanism rotates forward and backward.

  Next, the parison extrusion process in the above embodiment will be described based on the explanatory diagram of FIG. 8 and the time chart of FIG. In FIG. 8, the main resin material M <b> 1 and the sub resin material M <b> 2 flowing inside the extrusion head 4 are illustrated with different hatchings.

  FIG. 9 shows operations of the main extruder 3, the sub-extruder 5, and the gear pump 16 during one molding cycle corresponding to the extrusion of one parison of the resin molded product 15. The main extruder 3 is continuously driven during the molding cycle, and continuously supplies the main resin material to the main annular flow path 27. The sub-extruder 5 is stopped until time t1, and the gear pump 16 is stopped until time t2.

  FIG. 8A shows the state inside the extrusion head 4 from time t0 to time t1, and as shown in the figure, the main resin material M1 occupies the entire main annular flow path 27, and the die 22 The parison which consists only of the main resin material M1 is extruded from the discharge port 30. At this time, the slide valve 31 is biased upward by the pressure of the main resin material M1, and the seal surface 31c at the upper end is in contact with the seat surface 33a. Therefore, the secondary annular flow path 28 is reliably closed, and the secondary resin material M2 having a different color is prevented from being mixed.

  The sub-extruder 5 starts operating at time t1, and the gear pump 16 is driven in the forward rotation direction at time t2 slightly delayed from this time. Thereby, supply of sub resin material M2 is started. Then, the sub-extruder 5 stops operating at time t3, the gear pump 16 is temporarily reversed at time t4 slightly delayed from this, and the gear pump 16 is stopped at time t5. The section from time t2 to time t4 basically corresponds to the length of the desired colored layer.

FIG. 8B shows a state immediately after time t 2, and the pressure of the sub resin material M 2 on the upstream side of the slide valve 31 rises, so that the slide valve 31 is pushed down, and the sub annular channel 28. Is released. As a result, the auxiliary resin material M2 starts to merge along the outer peripheral portion of the main annular flow path 27 at the merge portion 29. FIG. 8C shows the flow of the resin materials M1 and M2 from the start of such merging to the time t4. As shown, the colored sub resin material M2 is the surface of the main resin material M1. Is overlaid as a colored layer. The joining of the sub resin material M2 that becomes the colored layer is started all at once by opening the slide valve 31, so that the starting point of the colored layer in the parison and hence the resin molded product 15 is substantially uniform over the entire circumference. After the sub-extruder 5 is stopped, when the gear pump 16 reverses at time t4, the pressure of the sub-resin material M2 on the upstream side of the slide valve 31 is instantaneously reduced. As a result, as shown in FIG. 8D, the slide valve 31 rises again, the seal surface 31c comes into contact with the seat surface 33a, and the auxiliary annular flow path 28 is closed. Thereby, the provision of the colored layer to the parison surface is completed. Even at the end point of this colored layer, the sub-annular flow path 28 is closed all at once by the slide valve 31, so that a boundary is obtained at a substantially uniform position over the entire circumference.

  As described above, in the above-described embodiment, by opening and closing the sub annular flow path 28 with the annular slide valve 31, the boundary that becomes the start point and the end point of the colored layer can be obtained at a more uniform position over the entire circumference. . In particular, in the above embodiment, the boundary of the colored layer can be obtained more clearly by using the gear pump 16 capable of normal rotation and reverse rotation in combination.

  In the above embodiment, the joining portion 29 of the secondary resin material is located immediately before the die 22 and the distance from the discharge port 30 to the joining portion 29 is relatively short, so that it is easier to switch between addition and stop of the colored layer. Become.

  By such steps, a container having two colors and color change in the horizontal direction as shown in FIG. 10 could be manufactured. In FIG. 10, the same plain portion as the drawing indicates a resin portion from the main resin passage, and the lattice portion above the resin portion indicates a resin portion from the sub resin passage.

DESCRIPTION OF SYMBOLS 3 ... Main extruder 4 ... Extrusion head 5 ... Sub extruder 16 ... Gear pump 21 ... Head body 22 ... Die 24 ... Outer mandrel 25 ... Inner mandrel 26 ... Core shaft 27 ... Main annular channel 28 ... Sub annular channel 31 ... Slide valve 32 ... Stopper

Claims (6)

A die and a core constituting a main annular flow path to which a main resin material is continuously supplied;
An outer peripheral side cylindrical member and an inner peripheral side cylindrical member configured to join the auxiliary annular flow path to which the secondary resin material is intermittently supplied to the outer peripheral portion of the main annular flow path;
The sub-ring is slidable by a predetermined amount in the sub-annular flow path, the pressure of the sub-resin material acts in the downward direction, the pressure of the main resin material acts in the upward direction, and seals according to the vertical sliding An annular slide valve whose surface opens and closes the auxiliary annular channel;
A die head comprising: The seal surface is formed on the upper end of the slide valve as an inclined surface that contacts the inclined seat surface of the inner cylindrical member.
2. A stopper portion that engages with a part of the outer peripheral cylindrical member and defines a lower limit position of the slide valve is provided protruding from the outer peripheral surface of the slide valve. The die head described in 1. A sealing surface that contacts the inclined seating surface of the outer peripheral cylindrical member is formed on the upper portion of the slide valve,
The stopper part which engages with a part of said inner peripheral side cylindrical member and prescribes the lower limit position of the slide valve is projected from the inner peripheral surface of the slide valve. The die head according to 1.   A gear pump capable of transporting material in both forward and reverse directions is added to a secondary resin material supply path between the secondary resin material extruder and the secondary annular flow path. 4. The die head according to any one of 3.   The die head according to any one of claims 1 to 4, wherein the main annular channel and the sub-annular channel merge at a position immediately before the die.   A molding machine comprising the die head according to claim 1.

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