JP3022378U - Ball check valve for injection molding machine - Google Patents

Abstract

(57) Abstract: In a ball check valve of an injection molding machine, since an outlet passage is provided near the inner wall of the heating cylinder in the conical portion of the screw head toward the inner wall of the heating cylinder, the molten resin is agitated / kneaded. However, it was difficult to change the color of the raw material and the resin, and the molded product had uneven color. SOLUTION: At least one of the outlet passages is drilled near the apex of the screw head.

Description

[Detailed description of the device]

[0001]

[Technical field to which the device belongs]

 The present invention relates to improvement of a ball check valve which is a check valve for preventing molten resin from flowing back, which is provided at a screw tip of an injection molding machine.

[0002]

[Prior art]

 The conventional ball check valve is as shown in FIG. 2, and a plurality of outlet passages 7 provided in the screw head 5 and communicating from the valve chamber 8 to the conical surface of the screw head are bored at the same angle with respect to the axis.

[0003]

[Problems to be solved by the device]

 When plasticizing in such a ball check valve, the outlet passage 7 opens from the valve chamber 8 toward the inner wall of the heating cylinder, so that a rapid flow of the molten resin does not occur near the axis of the heating cylinder. Molten resin tends to stay near the tip surface of the screw head. Therefore, a large amount of resin and time were required to replace the raw material resin. In addition, as described above, the rapidly flowing molten resin discharged radially from the screw head outlet passage 7 becomes a spiral vortex as the screw retracts as the screw rotates, and the molten resin accumulated in the heating cylinder is discharged. A striped pattern will remain on.

[0004]

[Means for Solving the Problems]

 Therefore, at least one outlet passage communicating with the valve chamber of the ball check type check valve is provided near the apex of the screw head.

[0005]

[Embodiment of device]

 The embodiment of the present invention is as shown in FIG. 1, and FIG. 2 shows a conventional example.

[0006]

Embodiment An embodiment of the present invention will be described in detail with reference to FIG. Reference numeral 1 is a heating cylinder into which the screw 2 is inserted so as to be rotatable and reciprocally movable. A female screw is provided at the front end of the screw 2 and is screwed with a mounting screw 11 of the housing 3. The base end of the housing 3 has the same diameter as the tip valley of the screw 2 so that there is no step when the housing 3 is screwed onto the screw 2. A plurality of inlet passages 10 are formed in a portion of the housing 3 having the same diameter as the screw tip valley portion and communicate with the valve chamber 8. The ball 4 is loosely inserted in the valve chamber 8, and the ball and the housing 3 come into line contact at the movement limit position on the inlet passage side of the ball 4, so that the molten resin does not flow backward when injecting the molten resin. I am trying.

A mounting screw 9 is provided on the outer periphery of the portion of the housing 3 forming the valve chamber 8 and is screwed with a female screw provided on the screw head. The screw head has a clearance between the outer periphery and the inner wall of the heating cylinder to the extent that no backflow of the molten resin occurs, and the screw head has a conical shape beyond the outer periphery. A plurality of outlet passages 6 and 7 communicating with the valve chamber 8 are bored on the conical surface. In the embodiment, one of the four outlet passages 6 is parallel to the axial center and the other is provided. The three outlet passages 7 are provided so as to be inclined toward the inner wall of the heating cylinder. However, in the conventional example shown in FIG. 2, all four outlet passages 7 are provided so as to be inclined at equal intervals toward the inner wall of the heating cylinder. However, the number of outlet passages 6 parallel to the axial center may be two or more, and even if the outlet passages 6 are not necessarily parallel to the axial center, the outlets are closer to the apex of the conical shape of the screw head than the other outlet passages 7. It may be provided.

Next, the flow state of the molten resin in the check valve of the present application will be described. In FIG. 1, the illustrated portion of the screw 2 is a metering zone, and the molten resin plasticized and melted in the feed zone and the compression zone (not shown) is conveyed by the groove 12. The molten resin that has entered the valve chamber 8 from the inlet passage 10 moves the balls 4 in the flow direction of the molten resin due to the resin pressure, passes through the gap of the valve chamber in which the balls 4 are loosely inserted, and then passes from the outlet passage 7 to the screw. It is carried into the heating cylinder in front of the head.

At this time, the three outlet passages 7 are directed toward the inner wall of the heating cylinder, and the one outlet passage 6 is directed toward the vicinity of the apex of the screw head. The molten resin is discharged into the vicinity of the outer circumference and the vicinity of the inner circumference of the screw head without forming a spiral shape, so that sufficient stirring and kneading are performed.

[0010]

[Effect of device]

 Therefore, it is possible to reduce the amount of time and resin required for exchanging the raw material resin, and since the stirring and kneading during plasticization are good, the accumulated molten resin becomes uniform and uneven coloring may occur in the molded product. Disappear.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which the ball check valve of the present invention is attached to a screw and fitted into a heating cylinder.

FIG. 2 is a cross-sectional view showing a state in which a conventional ball check valve is attached to a screw and fitted into a heating cylinder.

[Explanation of symbols] 1 heating cylinder 2 screw 3 housing 4 ball 5 screw head 6 outlet passage 7 outlet passage 8 valve chamber 9 mounting screw 10 inlet passage 11 mounting screw 12 groove

Claims (1)

[Scope of utility model registration request] 1. A ball check type check valve in an injection molding machine, wherein at least one outlet passage of an outlet passage communicating with a valve chamber is bored near a top of a screw head. valve.