JP2010162817A - Plasticizing device and plasticizing method for plastic raw material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a nickel-based alloy has a comparatively low hardness, even the one in which a press forging working is carried out to have strength, the hardness thereof is about HV380-440, and is quite low to the hardness HV800-900 of hard chrome plating currently used abundantly, thereby a screw and a heating tube in which a nickel-based alloy processing is carried out has corrosion resistance but scarcely has wear resistance, thereby bite is generated with the spinning of a screw under plasticization. <P>SOLUTION: In the plasticizing method for a plastic raw material, a raw material adjusting device 13 limits the amount of supply and supplies a plastic raw material M which generates a corrosive gas during plasticization into a heating tube 3, and the plastic raw material M is plasticized by a screw 4 and the heating tube 3 in which a nickel-based alloy processing is performed to the opposed surface of a screw 4 and/or an opposed surface of the heating tube 3 on both the opposed surfaces of the screw 4 and the heating tube 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plasticizing apparatus and a plasticizing method for safely plasticizing a resin raw material that generates corrosive gas during plasticization.

  When plasticizing fluororesin or PPS resin, corrosive gas is generated. In particular, when the fluororesin is plasticized, hydrogen fluoride gas is generated, which corrodes the screw and the heating cylinder. In order to protect the screw and the heating cylinder from such a corrosive gas, conventionally, as disclosed in Patent Document 1, the opposing surfaces of the screw and the heating cylinder have been formed of a Ni-based alloy.

Japanese Patent Publication No. 3-38328

  However, the Ni-based alloy has a relatively low hardness, and even if it is strengthened by forging, the hardness is about HV380 to 440, compared with the hard chrome plating hardness HV800 to 900, which is widely used. It is quite low. For this reason, a screw or a heating cylinder treated with a Ni-based alloy has corrosion resistance but poor wear resistance, so that there is a risk that warpage may occur as the screw rotates during plasticization.

  Therefore, the resin raw material that generates corrosive gas during plasticization is supplied to the heating cylinder by limiting the supply amount by the raw material adjusting device, and the opposing surface of the screw and / or the heating cylinder in both opposing surfaces of the screw and the heating cylinder. By plasticizing the resin raw material with the screw and the heating cylinder having the Ni-base alloy treatment on the opposite surface of the steel, the plasticizing behavior of the resin raw material in the heating cylinder is stabilized, and the screw is biased in the heating cylinder. It was designed to keep the core without core.

  According to the plasticizing apparatus and the plasticizing method of the resin raw material of the present invention, the screw and the heating cylinder can be protected from damage without being corroded.

FIG. 1 is a longitudinal sectional view showing an outline of a plasticizing apparatus of the present invention.

  The plasticizing apparatus 1 plasticizes the resin raw material M that is restricted and conveyed by the raw material adjusting apparatus 13 and is supplied into the heating cylinder 3 by the heating cylinder 3 and the screw 4 that rotates in the inner hole thereof to form a molten raw material MM. Is. The generated molten raw material MM is injected into a mold (not shown) through a nozzle 8 provided on the front end surface of the heating cylinder 3 by a screw 4 that moves forward in the inner hole of the heating cylinder 3. In this case, the plasticizing apparatus 1 constitutes a part of an injection molding machine. Further, the screw 4 may be configured to be rotatable while being unable to move forward and backward within the inner hole of the heating cylinder 3, and the nozzle 8 on the front end surface of the heating cylinder 3 may be replaced with a die and extruded while shaping the molten raw material MM. . In this case, the plasticizing apparatus 1 functions as an extruder.

  The screw 4 has a wall shape as a flight 2 on the outer periphery of a round bar as a shaft portion 15 having a small diameter at the base and a large diameter at the tip and a conical shape that smoothly connects the small diameter and the large diameter. The protrusion is formed in a spiral shape continuously from the base to the tip. The outer diameter of the flight 2 is formed to be slightly smaller than the inner diameter of the inner hole of the heating cylinder 3, the screw 4 can smoothly rotate within the inner hole of the heating cylinder 3, and the molten raw material MM leaks at the top of the flight 2. There is no such thing. The screw 4 is divided in the axial direction with a small diameter section at the base portion of the shaft portion 15 as a feed zone ZF, an intermediate portion of the shaft portion 15 as a compression zone ZC, and a large diameter section at the tip portion of the shaft portion 15 as a metering zone ZM. Has been. The through hole provided in the upper surface of the rear portion of the heating cylinder 3 communicates with the raw material adjusting device 13 through the through hole of the housing 9 that holds the heating cylinder 3, and the communication hole serves as the raw material dropping port 10. The screw 4 is disposed in the inner hole of the heating cylinder 3 so that the feed zone ZF is located below the raw material dropping port 10.

  A screw head 6 for loosely fitting the ring valve 5 is screwed to the front end surface of the screw 4 to constitute a backflow prevention valve. The backflow prevention valve may have another configuration using a ball or the like instead of the ring valve, and may not be provided with a backflow prevention valve like an extruder. A plurality of heaters 7 are attached to the outer peripheral surface of the heating cylinder 3 so as to correspond to the feed zone ZF, the compression zone ZC, and the metering zone ZM. The heater 7 adjusts the temperature of each zone to an appropriate temperature.

  Ni-base alloy treatment is applied to the inner hole surface of the heating cylinder 3, which is a surface facing the heating cylinder 3 and the screw 4, and the outer surface including the shaft 15 and the flight 2 of the screw 4. This treatment may be performed only on either the inner hole surface of the heating cylinder 3 or the outer surface of the screw 4. For the Ni-based alloy treatment, Hastelloy or plasthard registered as a trademark is suitably employed, but any Ni-based alloy can be employed regardless of the type and ratio of other alloys. Moreover, the process and formation state of Ni base alloy processing are not ask | required. Such Ni-based alloy treatment has corrosion resistance against corrosive gas generated during plasticization of fluororesin and PPS resin, etc., but particularly against hydrogen fluoride gas generated during plasticization of fluororesin. And effective. The Ni-based alloy treatment may be applied to the surface of the resin material M such as the raw material dropping port 10 and the backflow prevention valve other than the facing surface of the heating cylinder 3 and the screw 4 and the passage surface of the molten raw material MM to improve the corrosion resistance. It goes without saying.

  The raw material adjusting device 13 has a cylinder 12 disposed on the upper surface of the housing 9 with an opening communicating with the raw material dropping port 10, and a rotation device that is rotatably inserted into an inner hole of the cylinder 12 and has an arbitrary rotation speed. And a hopper 14 provided in the upper surface opening of the cylinder 12 on the side opposite to the side corresponding to the raw material dropping port 10 of the feed screw 11. In addition, as a raw material control apparatus, the thing of such a structure is preferable at the point which controls the supply amount of the resin raw material M stably and precisely, However, The thing of another structure using a measuring rod, a shutter, etc. may be used. .

  When the rotational speed set value of the feed screw 11 is 100%, that is, when the raw material adjusting device 13 supplies the resin raw material M into the heating cylinder 3 without being restricted, the resin raw material M fills the raw material dropping port 10. The supply of the resin material M is controlled to such an extent that it is performed. At that time, the plasticizing apparatus 1 exhibits the maximum plasticizing ability determined by its configuration. The feed screw 11 of the raw material adjusting device 13 drops a predetermined amount of the resin raw material M according to the rotational speed set value set to an arbitrary value of 100% or less while the screw 4 is rotated and plasticized. It is supplied into the heating cylinder 3 through the port 10.

  In this embodiment, when the rotational speed set value of the feed screw 11 (the supply amount of the resin raw material M) is an amount corresponding to 40% of the maximum plasticizing capacity, the flight 2 and the shaft portion of the screw 4 15 is substantially filled with the resin raw material M, and only the top of the flight 2 can be seen from above the raw material dropping port 10. Thus, when the supply amount of the resin raw material M is less than the amount corresponding to 40% of the maximum plasticizing capacity and at least the top of the flight 2 can be expected from above the raw material dropping port 10, plasticization is stably performed. The screw 4 is well-maintained by the semi-molten raw material MH and the molten raw material MM, and is not eccentric and pressed against one side, so that the opposing surfaces of the screw 4 and the heating cylinder 3 do not cause damage such as curling. It is.

  That is, the resin raw material M that is supplied in a limited manner from the raw material adjusting device 13 into the heating cylinder 3 does not fill the space defined by the shaft portion 15 and the flight 2 in the feed zone ZF. It is conveyed forward while receiving a sufficient amount of heat to melt from the surface. When this resin raw material M is conveyed to the compression zone ZC, it receives a larger amount of heat from the inner hole surface of the heating cylinder 3, so that part is gradually melted and scraped off by the flight 2 together with the unmelted resin raw material M Stirring is performed on the front side wall surface of the flight 2, and the height of the flight 2 from the shaft portion 15 gradually decreases, so that the flight 2 is conveyed forward while being compressed. Therefore, in the compression zone ZC, the resin raw material M becomes a semi-molten raw material MH in which molten raw materials are mixed. And since the supply of the resin raw material M is restricted, the semi-molten raw material MH does not completely fill the space defined by the shaft portion 15 and the flight 2, and the resin raw material M is sufficient in the feed zone ZF. Since the resin is preheated and easily melted, the content of the resin raw material M is low. Therefore, the eccentricity of the screw 4 based on the force when the flight 2 bites the unmelted resin raw material M is reduced, and the outer surface of the screw 4 due to the pressing force of the screw 4 on the inner hole surface of the heating cylinder 3 and / or Or while being able to prevent damage to the inner-hole surface of the heating cylinder 3, the rotational speed of the screw 4 is stably controlled and good plasticization can be performed. When the semi-molten raw material MH reaches the metering zone ZM, the space defined by the shaft 15 and the low flight 2 is completely filled and becomes the molten raw material MM. In the metering zone ZM, since the resin raw material M is not contained at all and only the molten raw material MM having lubricity is filled, the screw 4 is very well cored.

  In addition, this invention includes what can be implemented in the aspect which added various change, correction, improvement, etc. based on the knowledge of those skilled in the art. Further, it goes without saying that any of the embodiments to which the above-mentioned changes are added is included in the scope of the present invention without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Plasticization apparatus 2 Flight 3 Heating cylinder 4 Screw 5 Ring valve 6 Screw head 7 Heater 8 Nozzle 9 Housing 10 Raw material dropping port 11 Feed screw 12 Cylinder 13 Raw material control apparatus 14 Hopper 15 Shaft part M Resin raw material MH Semi-molten raw material
MM molten raw material ZF feed zone ZC compression zone ZM metering zone

Claims (4)

While performing the Ni-based alloy treatment on the opposing surface of the screw and / or the opposing surface of the heating cylinder in both opposing surfaces of the screw and the heating cylinder,
A plasticizing apparatus for a resin raw material, comprising: a raw material adjusting device for supplying the raw material with restriction to the heating cylinder. Resin raw material that generates corrosive gas during plasticization is supplied to the heating cylinder by limiting the supply amount with the raw material regulator,
A resin characterized in that the resin raw material is plasticized by the screw and the heating cylinder in which the Ni-based alloy treatment is applied to the opposing surface of the screw and / or the opposing surface of the heating cylinder in both opposing surfaces of the screw and the heating cylinder. Raw material plasticization method.   The method for plasticizing a resin material according to claim 2, wherein the resin material is a fluororesin.   The method for plasticizing a resin raw material according to claim 2 or 3, wherein the resin raw material is supplied while being limited to an amount corresponding to a state in which a flight top of the screw can be expected from a raw material dropping port.

Images