JP4785062B2 - Injection device with screw heating circuit - Google Patents

Description

  The present invention relates to an injection apparatus provided with a heating circuit using a heat medium in a screw shaft of an injection screw.

  In the conventional inline screw type injection device, a through hole extending in the axial direction is formed in the injection screw, and an opening is formed in the base end side portion and the distal end side portion protruding from the heating cylinder of the through hole. While the tip of the hole communicates with the inside of the heating cylinder, a coupling having a communication hole is fitted to the opening part of the base end side portion, and the bracket is attached to the movable part of the injection cylinder so that the coupling moves together with the injection screw. The hot air can be pumped from the coupling into the screw shaft, and the injection screw is heated by blowing the hot air generated by the hot air generator through the through hole into the heating cylinder.

In addition, a tubular body is inserted from the rear end into the body portion having a cylindrical shape and a screw on the outer periphery, and an inner and outer double heating circuit that is folded back at the distal end of the tubular body by the tube body is formed in the body portion, There is also a plasticizing device in which the rear end is fixed to the rotating part of the swivel joint of the heat medium temperature control device, and the heat medium supplied from the heat medium temperature control device to the external circuit is circulated to the heat medium temperature control device via the internal circuit. .
Japanese Patent Laid-Open No. 4-40898 JP 2005-262812 A

  In the screw heating means employed by the conventional in-line screw type injection device, a coupling connected to the hot air generator is fitted in an intermediate portion of the screw rear portion between the heating cylinder and the movable portion of the injection cylinder. Therefore, the most advanced position of the injection screw is where the coupling comes into contact with the rear end of the heating cylinder, and the advance stroke of the injection screw is shorter than the normal one.

  This forward stroke can be lengthened by moving the fitting position of the coupling to the movable part side, but when the coupling approaches the movable part, the heating of the movable part by heat transfer from the shaft part becomes stronger, The operating oil of the injection cylinder and the lubricating oil of the device will deteriorate due to heating. For this reason, the injection screw has a special specification in which a shaft portion protruding from the heating cylinder is formed long.

  The passage in the injection screw is one-way, and the hot air after heating the screw blows into the molten material in the heating cylinder, so a part of the hot air is taken into the molten material as bubbles and becomes hot due to compression. This may cause undesired material burning. For this reason, it has the subject that it is difficult to employ | adopt as a heating means of an injection screw.

  When the inner and outer double heating circuit is formed in the screw body by inserting the tube as in the conventional plasticizing device, the heat medium temperature control device connected to the rear end of the screw is pumped to the outer circuit. Since the heat medium heats the screw body and then returns to the inner circuit at the tip of the tube and returns to the heat medium temperature control device, the problem as in the one-way case does not occur. However, the screw body is fixed to the swivel joint of the heat medium temperature adjusting device together with the internal tube body, and the rear end is supported by the heat medium temperature adjusting device, and the screw body portion rotates even in the cylinder. Since it cannot move forward and backward, it is difficult to adopt it as a heating means for an injection screw that moves forward and backward in the heating cylinder.

  An object of the present invention is to employ an internal / external double heating circuit to heat an injection screw in a heating cylinder in an injection apparatus, and to provide a heat medium supply block around the outside of the screw. It is an object of the present invention to provide an injection device equipped with a new screw heating circuit that can reduce the forward stroke of the injection screw within an allowable range and that is less affected by heating due to heat transfer to the drive device connected to the screw rear end.

According to the above-mentioned object, the present invention provides an annular supply block having a heating medium supply port concentrically attached to the rear end of the heating cylinder, an injection screw rotatably and reciprocatingly provided in the heating cylinder through the supply block, and a screw. A heating circuit in the screw shaft that is formed into an inner and outer double by a long hole drilled in the axial direction from the rear end of the shaft and a tube inserted in the long hole, and that is folded at the tip of the tube, and the injection screw Drilling in the screw shaft from the circuit inlet at the rear of the screw shaft that is drilled in the shaft portion of the portion facing the supply port at the last retracted position and communicated with the outer path of the heating circuit, and from the sealing member at the rear end of the tube body. A circuit outlet at the rear end of the screw shaft communicating with the inner circuit of the circuit, and the circuit outlet opens into an annular groove for connection formed on the outer peripheral surface of the rear end of the screw shaft. A pair of the inner edges fitted into the annular groove and coupled to each other Ri becomes a discharge portion of the gap between the joint by ring, is that.

Either the supply port or the circuit inlet opens into an annular groove provided on the inner peripheral surface of the supply block or the outer peripheral surface of the screw shaft, and the inner peripheral surface of the supply block and the outer peripheral surface of the screw shaft are connected to the supply block. It is said that it is airtightly sealed by a seal ring embedded outside the inner surface .

  In this invention, since the annular supply block having the heat medium supply port is attached to the heating cylinder side by side, the injection stroke shortened by the supply block protruding from the heating cylinder is within an allowable range, and the length of the normal specification The injection screw can be provided with a heating circuit. Further, since the supply block serves as the rear end of the heating cylinder, the injection screw can be inserted in the same manner as in the normal specification.

  Even if the heating circuit in the screw shaft is formed into an inner and outer double by a long hole drilled in the axial direction from the rear end of the screw shaft and a tube inserted in the long hole, the circuit inlet and circuit Since the outlet is provided back and forth at the rear part of the screw shaft, it can be employed without any trouble in the injection device that rotates and moves back and forth within the heating cylinder. In addition, the circuit inlet connected to the external circuit is located in the supply block at the rear end of the heating cylinder, and the heat medium supplied to the external circuit in relation to the internal circuit in the tube flows forward in the screw shaft. Heating to the screw shaft at the rear of the circuit entrance is small, and since the shaft portion exposed to the outside is long, heat transfer to the screw rear end due to heat radiation is also small, so that the heating device is not affected. Therefore, the injection screw can be heated with a high-temperature heat medium.

  Also, the supply port of the supply block and the circuit inlet of the screw shaft are connected at the last retracted position of the injection screw, and the connection is interrupted by the screw advancement, so the supply of the heat medium to the heating circuit is stopped at the last retracted position. Since the time is limited and the supply is stopped during screw movement, heating of the injection screw by the heat medium is automatic intermittent heating by repeated movement and stop of the injection screw. As a result, heating with a high-temperature heat medium, which is easily overheated by continuous heating with constant supply of the heat medium, can be performed without intermittent operation by the valve device, thus simplifying the heating device.

  In addition, the circuit outlet is opened in an annular groove for connection at the rear end of the screw shaft so that the heat medium after heating the internal circuit can be discharged from the gap between the annular groove and the joint. Therefore, it is possible to safely discharge the heat medium out of the apparatus because the medium temperature is lowered by heat exchange at the time of discharge.

  In the figure, reference numeral 1 denotes a heating cylinder having a nozzle member (not shown in the figure) at the tip and a normal structure having a material supply port 2 on the rear part, and an injection screw 3 is provided therein so as to be rotatable and movable back and forth. Reference numeral 4 denotes a holding plate for the heating cylinder 1, and a rear end portion of the heating cylinder 1 is fitted and fixed to the center of the board from the outer surface of the board to the inner surface of the board. Reference numeral 5 denotes a movable portion of a hydraulic or electric drive device for the injection screw 3, which is not described in detail, but has a normal structure. The injection screw 3 abuts the rear end of the screw shaft 31 against the movable portion 5, and a pair of It is connected by a joint 6 by a split ring.

  Reference numeral 7 denotes a heat medium supply block, which is formed by drilling a supply port 71 in an annular block having the same inner diameter as the inner diameter of the heating cylinder 1, and a seal ring 72 outside the inner peripheral surface where the supply port 71 is opened. Is buried. The supply block 7 is concentrically attached to the rear end of the heating cylinder 1 with an O-ring fitted to the opening edge with the supply port 71 facing upward, and the injection screw 3 is inserted into the heating cylinder through the supply block 7. is there.

  8 is a heating circuit provided in the center of the inside of the screw shaft 31 and is formed by a long hole 9 drilled in the axial direction (feed zone) from the rear end of the screw and a small-diameter tube body 10 inserted into the long hole 9. The inner and outer double circuits 8a and 8b are folded back at the tip of the tube body. Further, the rear end of the tubular body 10 is fitted to the sealing member 11 of the long hole 9 and fixed to the screw shaft 31. An extension path 8b 'of the internal circuit 8b is formed in a T shape in the front portion of the sealing member 11. It is drilled.

Reference numeral 12 denotes a circuit inlet formed in the rear part of the screw shaft 31 and connected to the outer circuit 8a. As shown in FIG. 2, at the last retracted position of the injection screw 3 , the screw shaft rear part of the part facing the supply port 71 is provided. It is drilled. A plurality of circuit inlets 12 are opened in an annular groove 12 ′ provided on the outer peripheral surface of the screw shaft 31, so that the heat medium from the supply port 71 flows into the plurality of circuit inlets 12 through the annular groove 12 ′. It is. In some cases, an annular groove 71 'can be provided on the inner surface of the supply block 7 where the supply port 71 is opened, as shown by the chain line, and the annular groove 12' can be omitted.

  Reference numeral 13 denotes a plurality of circuit outlets formed in the rear end portion of the screw shaft 31 and opens into a connecting annular groove 14 formed on the outer peripheral surface. The inner edge of the joint 6 is formed by coupling the split ring to the annular groove 14. Is fitted. The circuit outlet 13 is connected to the inner circuit 8b through the extension path 8b 'of the sealing member 11, and the heat medium can be discharged to the outside by using the gap between the annular groove 14 and the joint 6 as a discharge portion.

  In the above configuration, when the heat medium (for example, hot air) pipe line 15 is connected to the supply port 71 of the supply block 7 and the hot air is pumped from the blower, the hot air flows from the circuit inlet 12 into the outer circuit 8a, and the screw shaft portion. While 31 is heated, it flows to the tip of the long hole 9. When the tip of the long hole is reached, it flows into the inner circuit 8b from the tip of the tube, and is discharged from the circuit outlet 13 through the extension path 8b 'in the sealing member 11.

The hot air is pumped to the heating circuit 8 when the injection screw 3 is at the last retracted position, and the circuit inlet 12 is positioned at the supply port 71 as shown in FIG. Occurs when connected to the circuit inlet 12. When the injection screw 3 moves forward from the last retracted position, the position of the circuit inlet 12 shifts from the supply port 71 as shown in FIG. 3, and the supply port 71 is blocked by the screw shaft 31, and the heating circuit 8 and the pipe line 15 are moved. Is shut off and hot air pressure feed stops automatically.

  Therefore, the heating of the injection screw 3 by hot air is not performed at the time of material measurement by screw retraction and at the time of material injection by screw advance, and the rear part of the screw shaft 31 is exposed to the outside during the transition from the end of measurement retraction to the next injection advance. It is limited to the stop time (for example, 1 second). As a result, heating by the heat medium is intermittent heating that is automatically generated by repeatedly moving and stopping the injection screw 3.

  In addition, since there is no flow of the heat medium in the screw shaft after the circuit inlet 12, heating is small and the shaft portion exposed to the outside is long, so heat transfer to the rear end of the screw due to heat radiation is also small. Since there is no influence of heating, the injection screw 3 can be heated by a high-temperature heat medium. For example, in the case of a wax having a low melting temperature (50 to 60 ° C.), if the screw temperature is low, it adheres to the surface of the screw and solidifies, so hot air heated at a high temperature (400 ° C.) is supplied as a heat medium, thereby Can be heated to prevent adhesion of molten wax.

  The heated heating medium flowing in the inner circuit 8b is discharged to the outside through the gap between the annular groove 14 and the joint 6 from the circuit outlet 13 opened in the connecting annular groove 14 at the rear end of the screw shaft. The Since this discharge occurs only during the supply of the heat medium, the discharge is intermittent. In the discharge from the gap, the heat medium with the remaining heat is prevented from ejecting strongly from the circuit outlet 13 and the medium temperature is lowered by the heat exchange with the joint 6 at the time of discharge. It can be discharged outside the machine.

It is a principal part vertical side view in the screw retreat position of the injection apparatus which has a heating circuit of this invention. It is a rear expanded sectional view same as the above. It is a rear part expanded sectional view at the time of screw advance. FIG. 2B is a sectional view taken along line B-B.

DESCRIPTION OF SYMBOLS 1 Heating cylinder 3 Injection screw 31 Screw shaft 5 Movable part of drive device 6 Joint 7 Heat medium supply block 71 Heat medium supply port 72 Seal ring 8 Heating circuit 8a Outer circuit 8b Inner circuit 8b 'Extension path of inner circuit 9 Screw Long hole in shaft 10 Tube 11 Sealing member of long hole 12 Circuit inlet 13 Circuit outlet 14 Annular groove for connection

Claims (1)

An annular supply block having a heat medium supply port concentrically attached to the rear end of the heating cylinder;
An injection screw provided in the heating cylinder through the supply block so as to be rotatable and movable back and forth;
A heating circuit in the screw shaft that is formed into an inner and outer double by a long hole drilled in the axial direction from the rear end of the screw shaft and a tube inserted in the long hole, and folded at the tip of the tube;
A circuit inlet at the rear of the screw shaft that is drilled in the shaft portion of the portion facing the supply port at the last retracted position of the injection screw and communicated with the outer circuit of the heating circuit;
A screw shaft drilled from the sealing member at the rear end of the tubular body, and a circuit outlet at the rear end of the screw shaft communicating with the inner circuit of the heating circuit ;
The circuit outlet is opened in an annular groove for connection formed on the outer peripheral surface of the rear end portion of the screw shaft, and a joint by a pair of split rings that are coupled to each other by fitting the inner edge of the annular groove to the annular groove. The gap between
An injection device provided with a screw heating circuit.

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