TW201341156A - Countercurrent-proof device - Google Patents

Abstract

A countercurrent-proof device includes a threaded rod, a head fixed on one end of the threaded rod, a tube wrapped on the threaded rod and a sealing gasket fixed on the threaded rod. A first gap is formed between the threaded rod and the tube defines for the molten plastic passing through. The tube is located between the head and the sealing gasket. When the device is working, the threaded rod is rotated to drive the molten plastic to flow towards the first gap. Therefore, the tube and the sealing gasket forms a second gap for the molten plastic passing therebetween, and the second gap communicates with the first gap. When the work is finished, the threaded rod is rotated reversely to drive the threaded rod to move toward the tube sealing the second gap.

Description

Anti-backflow device

The invention relates to a backflow prevention device, in particular to a backflow prevention device applied to an injection molding machine.

The plastic injection molding machine generally includes a syringe having a heating cylinder, a screw that is rotatable and movably mounted in the heating cylinder. During the metering process, the screw is rotated back in the normal direction so that the resin flows out of the funnel, melts and is stored in the area in front of the screw head. During the injection molding process, the screw is fed in to inject the molten resin into the mold from the injection nozzle.

After the metering step is completed, in order to prevent the resin from being stored in the front area of the screw head during the injection molding process, it is often necessary to arrange a backflow prevention device in the plastic injection molding machine. However, in the conventional anti-backflow device, when the metering step is completed and the withdrawal is performed before the start of the injection molding step, the resin in the screw easily flows forward into the area in front of the screw head, thereby causing storage in front of the screw head. The amount of resin in the area changes.

In view of this, it is necessary to provide a backflow prevention device which can effectively prevent the plastic from flowing backward and has a simple structure.

An anti-backflow device includes a screw, a rubber head disposed at one end of the screw, and a rubber sleeve sleeved on the screw, and a first gap between the screw and the rubber tube for passing the molten plastic is provided. The anti-backflow device further includes a sealing ring fixed on the screw, and the rubberizing cylinder is disposed between the rubberizing head and the sealing ring. When measuring, the screw rotates under the action of an external force and drives the molten plastic toward the first a gap flows, thereby pushing a gap between the rubber tube and the sealing ring to pass through the molten plastic and communicating with the first gap. When the metering is finished, the screw is rotated in the opposite direction to make the screw face the The cartridge moves to cause the seal to abut against the glue cartridge to seal the second gap.

After the metering of the anti-backflow device, the sealing ring and the rubberizing cylinder are resisted, so that the plastic cannot flow back. Moreover, the anti-backflow device only includes the screw, the glue head, the rubber tube and the sealing ring, so as to prevent the plastic from flowing backward after metering, the structure of the anti-backflow device is relatively simple.

Referring to FIG. 1 to FIG. 3 , the anti-backflow device 100 includes a screw 10 , a rubber head 20 disposed at one end of the screw 10 , a set of a rubber tube 30 disposed on the screw 10 , and a seal fixed to the screw 10 . The coil 40 is disposed between the rubber head 20 and the sealing ring 40, and a first gap 50 through which the plastic passes is disposed between the rubber tube 30 and the screw 10.

The other end of the screw 10 is connected to a driving device (not shown) of the injection molding machine, and the screw 10 is rotatable under the driving of the driving device and can advance and retreat in the axial direction of the screw 10.

The rubber head 20 has a substantially conical shape, and a plurality of plastic grooves 22 through which the plastic flows are opened in the radial direction. The plastic head 20 is also provided with an end wall 24 adjacent to one end of the rubber cylinder 30, and the end wall 24 is abutted against the rubber cylinder 30.

A plurality of latching blocks 32 and at least one abutting block 34 are respectively disposed on the one end of the rubber tube 30. The latching block 32 and the abutting block 34 are respectively received in the plasticizing tank 22, And the length of the block 32 is greater than the length of the abutting block 34. The block 32 is for resisting the groove wall forming the glue groove 22 to restrict the rotation of the screw 10 relative to the rubber tube 30, and the abutting block 34 is for resisting the end wall 24.

The seal ring 40 is made of a resilient material such as rubber.

Please refer to FIG. 4 and FIG. 5 together. When using the anti-backflow device 100, refer to the following steps:

During the metering, the screw 10 is rotated and fed by the driving device, and the plastic squeezes the rubber cylinder 30 to move toward the rubber head 20 to form a second gap 60 between the rubber cylinder 30 and the sealing ring 40, so as to sequentially flow the plastic. The second gap 60 and the first gap 50 pass. When the metering is completed, the screw 10 is driven by the driving device toward the rubber cylinder 30. When the abutting block 34 is disengaged from the rubber tank 22, the driving device drives the screw 10 to rotate in the opposite direction to press the abutting block 34 and the rubber head. The end wall 24 of the 20 is resisted, and the end of the rubber cylinder 30 against the top block 34 simultaneously presses against the seal ring 40 to eliminate the second gap 60. When the block 32 is held by the groove wall forming the glue groove 22, the screw 10 stops rotating, and the second gap 60 is sealed at this time.

After the metering prevention device 100 is metered, the sealing ring 40 abuts against the rubber tube 30, thereby sealing the second gap 60 so that the plastic cannot flow backward. Moreover, the anti-backflow device 100 includes only the screw 10, the rubber head 20, the rubber tube 30 and the sealing ring 40, which can prevent the plastic from flowing backward after metering. Therefore, the anti-backflow device 100 has a simple structure.

In addition, various modifications, additions and substitutions in the form and details may be made by those skilled in the art in the scope and spirit of the invention. It is a matter of course that various modifications, additions and substitutions made in accordance with the spirit of the invention are intended to be included within the scope of the invention.

100. . . Anti-backflow device

10. . . Screw

20. . . Plastic head

30. . . Rubber tube

40. . . Seal ring

50. . . First gap

60. . . Second gap

twenty two. . . Plastic tank

twenty four. . . End wall

32. . . Block

34. . . Topping block

1 is an exploded view of a backflow prevention device according to a preferred embodiment of the present invention;

Figure 2 is an assembly view of the anti-backflow device shown in Figure 1;

Figure 3 is a cross-sectional view of the anti-backflow device of Figure 2 taken along line III-III;

Figure 4 is a view showing the state of use of the backflow prevention device shown in Figure 2;

Figure 5 is a cross-sectional view of the anti-backflow device of Figure 4 taken along line V-V.

10. . . Screw

20. . . Plastic head

30. . . Rubber tube

40. . . Seal ring

50. . . First gap

60. . . Second gap

twenty two. . . Plastic tank

Claims (7)

The anti-backflow device comprises a screw, a rubber head disposed at one end of the screw, and a rubber sleeve sleeved on the screw, and a first gap between the screw and the rubber tube for passing the molten plastic is provided. The improvement is that the anti-backflow device further comprises a sealing ring fixed on the screw, and the rubberizing cylinder is disposed between the rubberizing head and the sealing ring. When measuring, the screw rotates under the action of an external force and drives the molten plastic. Flowing toward the first gap, and pushing a second gap between the rubber tube and the sealing ring for the molten plastic to pass through and communicating with the first gap, when the metering is finished, rotating the screw in the opposite direction to The screw moves toward the canister to cause the sealing ring to abut against the glue cartridge to seal the second gap. The anti-backflow device of claim 1, wherein the rubber cylinder is provided with a block and an abutting block adjacent to one end of the rubber head, and the rubber head is provided with a glue groove along a radial direction thereof. The block and the abutting block are respectively received in the glue groove. The anti-backflow device of claim 2, wherein the length of the block is greater than the length of the abutting block. The anti-backflow device of claim 2, wherein the adhesive head is provided with an end surface adjacent to one side of the rubber tube, and the top block and the end wall when the rubber tube is in contact with the sealing ring Resist. The anti-backflow device of claim 1, wherein the plastic head has a conical shape. The anti-backflow device of claim 1, wherein the sealing ring is made of an elastic material. The anti-backflow device of claim 6, wherein the sealing ring is made of rubber.