GAS DISCHARGE DEVICE FOR INJECTION MOLDING

Technical Field

[1] The present invention relates to a gas discharge device for injection molding; and more particularly, to a gas discharge device for effectively discharging gas from an injection molding machine to prevent products from being inferior.

Background Art

[2] An injection molding is a manufacturing process for forming objects, as of plastic or metal, by heating the molding material such as a resin to fluid state and injection it into a mold.

[3] An injection molding machine injects resin into a mold formed of a top mold unit joined with a bottom mold unit to form a target object.

[4] For such an injection molding process, compounds are prepared by putting them in a hopper. The compounds are small circular or rectangular chips made of plastic with a pigment, a stabilizer, a plasticizer and a filler. The compounds are inserted into a heating chamber and heated by an electric heat and high pressurized steam.

[5] The plastic molding material is heated at a predetermined temperature to transform it to the fluid state thereof. For example, if a molding material is styrene resin or polyvinyl chloride, it may be heated at about 170 °C. Or if a molding material is polypropylene, it may be heated at about 200°C. Then, the fluid state of the resin is injected into a mold through an injection port using a piston. After inserting the fluid state of the resin into the mold, it is hardened. After hardening, the formed object is took out from the mold by splitting the mold into a top molding unit and a bottom molding unit thereof.

[6] The injection molding may form various objects from a very small object to a large object, for example, weight about 10Kg. Since the injection molding may conveniently produce same objects through repeatedly performing the same injection molding processes, the injection molding is generally used for mass production.

[7] In case of using a plastic molding material to produce a target product, the fluid state of the molding material generates a gas and the inside of the mold is filled with the generated gas. Such gas inside the mold leaves scorch marks on the target product and it is a major factor of the inferior products.

[8] Therefore, a gas discharge device was developed to discharge the gas from the mold while injecting the fluid state of the molding material into the mold.

[9] Such a gas discharge device was introduced at Korea Utility Model No. 0136506 entitled "A GAS DISCHARGE DEVICE OF INJECTION MOLD."

[10] An injection molding machine with the conventional gas discharge device includes a flame having a molding cavity, a sprue bush where a molding material is injected, a runner for guiding the injected molding material from the sprue bush to the molding cavity formed on the flame, and a gas discharge unit for discharging gas generated from the molding material. The gas discharge unit includes at least one of gas discharge cores buried at the frame and having an top surface exposed to the runner between the sprue bush and the cavity and at least one of gas discharge path formed at the frame where the gas discharge core is buried by penetrating the frame to pass the gas. That is, the gas discharge unit discharges the gas flowing between the gas discharge core and the frame.

[11] However, the conventional gas discharge unit only discharges a small amount of the gas generated while the molding material is melting, for example, about 10% of the generated gas, because it discharges the gas from the mold.

[12] That is, the conventional gas discharge unit does not discharge the gas melted with the molding material although the conventional gas discharge unit may discharge gas from the front inside end of the injection molding machine. Disclosure of Invention Technical Problem

[13] It is, therefore, an object of the present invention to provide a gas discharge device for injection molding for increasing a gas discharging efficiency by discharging gas generated from a molding material while the molding material is melted.

[14] It is another object of the present invention to provide a gas discharge device for injection molding for preventing products from being inferior caused by insufficiently discharging gas through increasing the gas discharging efficiency.

Technical Solution

[15] In accordance with one aspect of the present invention, there is a gas discharge device for injection molding including: a solid body having a top side connected to a hopper and a bottom side connected to an injection molding machine, and including a barrier formed at a center of the solid body wherein the barrier has two ventilation holes, a gas chamber formed at a sealed side of the barrier and having a opened bottom side for holding gas discharged from the injection molding machine and a discharging chamber formed at other side of the barrier and having a sealed bottom side for discharging the gas discharged from the gas chamber through a filter; an insertion tube formed to be connected to the hopper, projected from a center of a top side of the gas chamber to an opened bottom side, having a wider upper portion and a narrower lower portion, and having a plurality of through-holes at an end of the insertion tube; a ventilation fan disposed at the ventilation hole for forcedly discharging a gas from the

gas chamber; a filter slot formed at a rear of the ventilation fan and the other side of the barrier for mounting a filter; and a filter inserted to the filter slot to filter and eliminate deleterious components of the gas.

[16] The solid body may further include an air inhaling hole formed on a predetermined side of the solid body which is other side of the ventilation fan.

[17] The body may further include: an air inhaling tube connected to the air inhaling hole for improving a flow of an inhaling air; and a connecting tube formed along a side of the insertion tube and connected to the air inhaling tube.

[18] The gas discharge device may further include: a sensor fixed at the solid body for sensing an amount of inserted molding material; and an air slider connected to the hopper for opening or closing a hole by shifting a valve plate in a length direction in response to a signal denoting whether the molding material is inserted or not generated from the sensor in order to control the amount of the inserted molding material.

Advantageous Effects

[19] A gas discharge device for injection molding according to the present invention increases a gas discharging efficiency by discharging gas generated from a molding material while the molding material is melted. [20] A gas discharge device for injection molding according to the present invention prevents products from being inferior caused by insufficiently discharging gas through increasing the gas discharging efficiency.

Brief Description of the Drawings

[21] The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which: [22] FlG. 1 is a perspective view of a gas discharging device for injection molding according to an embodiment of the present invention; [23] FlG. 2 is a cross-sectional view of the gas discharge device shown in FlG. 1 taken along the line II-II; [24] FlG. 3 is a cross-sectional view of the gas discharge device shown in FlG. 3 when the gas discharge device is in use; [25] FlG. 4 is a perspective view of a gas discharge device for injection molding according to another embodiment of the present invention; [26] FlG. 5 is a cross-sectional view of the gas discharge device shown in FlG. 4 taken along the line V-V; and [27] FlG. 6 is a cross-sectional view of the gas discharge device shown in FlG. 4 when the gas discharge device is in use.

Best Mode for Carrying Out the Invention

[28] Other objects and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, which is set forth hereinafter.

[29] FlG. 1 is a perspective view of a gas discharging device for injection molding according to an embodiment of the present invention, and FlG. 2 is a cross-sectional view of the gas discharge device shown in FlG. 1 taken along the line II-II.

[30] As shown in FlGs. 1 and 2, the gas discharge device 100 includes a body 110, an insertion tube 120, a ventilation fan 130, an air slider 140, a sensor 150, a filter slot 116 and a filter 160.

[31] The molding material is putted to the body 110 from a hopper 300 and inserted into the injection molding machine 400 through the insertion tube 120. A gas generated from the molding material fills a gas chamber 112 of the body 110 through a through- hole 122 formed at an end of the insertion tube 120. The gas in the gas chamber 112 is forcedly discharged to a gas-discharging chamber 117 by rotating the ventilation fan 130. And, the gas is filtered by the filter 160 disposed at the rear of the ventilation fan 130.

[32] Herein, the body 110 is shaped in a solid having an opened bottom side, includes the gas chamber 112 inside thereof and a barrier 115 formed at the center thereof and having two ventilation holes. As shown in FlG. 1, the body 110 is shaped in a rectangular pallelopiped in the present embodiment. However, the present invention is not limited by the shown shape of the body 110.

[33] The insertion tube 120 is connected to the hopper 300 and is formed from the top surface 116 of the gas chamber 112. The top side of the insertion tube 120 is opened to the hopper 300. The upper portion of the insertion tube 120 is wider and the lower portion of the insertion tube 120 becomes gradually narrowed. A plurality of through- holes 122 is formed on the lower end of the insertion tube 120 to discharge the gas from the molding material through the through-holes 122.

[34] The ventilation fans 130 are disposed at the ventilation holes formed at the barrier

115. Since the ventilation fans 130 are disposed at the ventilation holes to be separated at a predetermined distance by the barrier 115, the gas is effectively discharged without an additional exhaling device.

[35] The gas discharge device according to the present embodiment may further include a sensor 150 fixed at the body 110 for sensing an amount of inserted molding material, and an air slider 140 connected to the hopper 300 for controlling an amount of inserted molding material by opening or closing a hole 141 through sliding a belt plate 142 in response to a signal denoting whether the material is inserted or not from the hopper 300.

[36] Since the amount of the gas generated from the molding material varies according

to the amount of inserted molding material, it requires the gas discharge device to control the amount of inserted molding material.

[37] A method of controlling an amount of the inserted molding material will be described hereinafter.

[38] The sensor fixed at one side of the body 110 senses the amount of the inserted molding material and transmits a signal including information about the insertion amount of the molding material to a controller (not shown). The controller controls a valve plate 142 of the air slider 140 in response to the signal. The operation of the valve plate 142 may be embodied by a solenoid valve. But, the present invention is not limited thereby. The valve plate 142 opens or closes the hole 141 in response to the controller for controlling the insertion amount of the molding material.

[39] FlG. 3 is a cross-sectional view of the gas discharge device shown in FlG. 3 when the gas discharge device is in use.

[40] The gas discharge device 100 according to the present embodiment is disposed above a main cylinder 410 of the injection molding machine 400 and the hopper 300 is disposed above the gas discharge device 100.

[41] A screw rod 420 is disposed inside the main cylinder 410 and a plurality of helicoids 422 formed a circumference of the screw rod 420.

[42] The molding material in the hopper 300 is inserted into the main cylinder 410 through the insertion tube 120.

[43] While the molding material is melted and injected into the main cylinder 410, a gas is generated. The generated gas passes through the through-holes 122 and is externally discharged from the body 110 by rotating the ventilation fans 130. The screw rod 420 shifts the melted molding material in a predetermined direction while the screw rod 420 is rotated.

[44] Hereinafter, another embodiment of the present invention will be described.

[45] FlG. 4 is a perspective view of a gas discharge device for injection molding according to another embodiment of the present invention, and FlG. 5 is a cross- sectional view of the gas discharge device shown in FlG. 4 taken along the line V-V.

[46] As shown in FlGs. 4 and 5, the gas discharge device 200 according to another embodiment of the present invention includes a body 210, an insertion tube 220, a ventilation fan 230, an air slider 240, a sensor 250, a filter 260, a filter slot 219, a connection tube 270 and an air inhaling tube 280.

[47] Herein, the air inhaling tube 280 is disposed to connect an air inhaling hole 214 formed on a side 218 facing the ventilation fan 250.

[48] The connecting tube 270 is connected to the air inhaling tube 280 and is extended along a side of the insertion tube 220 to the end of the insertion tube 220 having a plurality of through-holes 222 to cover a predetermined portion of the end.

[49] The connecting tube 270 and the air inhaling tube 280 in the present embodiment are an example of an air inhaling unit. However, the air inhaling unit may be embodied by inhaling an air through the air inhaling hole 214 formed on the side 218 facing the ventilation fan 250 without including the connecting tube 270 and the air inhaling tube 280.

[50] If the molding material is putted into the insertion tube 220, the molding material is heated by a heating unit. Then, gas is created from the heated molding material while the molding material is melting down.

[51] The gas flows into a gas chamber 212 of the body 210 through the through-holes

220 formed on the end of the insertion tube 220. The gas filling the gas chamber 212 is forcedly discharged to a discharging chamber 217 by rotating the ventilation fans 230. The gas is filtered by the filter 260 disposed at rear of the ventilation fan 230.

[52] An air is inhaled through the air inhaling hole 214 and flows into the inside of the body through the air inhaling tube 280 and the connecting tube 270. That is, the inhaled air increases the efficiency of the ventilation fans 230 to quickly discharge gas, externally.

[53] FlG. 6 is a cross-sectional view of the gas discharge device shown in FlG. 4 when the gas discharge device is in use.

[54] The gas discharge device 200 according to another embodiment is disposed above a main cylinder 410 of the injection molding machine 400 and the hopper 300 is disposed above the gas discharge device 200.

[55] A screw rod 420 is disposed inside the main cylinder 410 and a plurality of helicoids 422 formed circumference of the screw rod 420.

[56] The molding material in the hopper 300 is inserted into the main cylinder 410 through the insertion tube 220.

[57] While the molding material is melted and injected into the main cylinder 410, gas is generated. The generated gas passes through the through-holes 222 and is externally discharged from the body 210 by rotating the ventilation fans 230. Herein, the gas is effectively discharged by the air inhaled through the air inhaling tube 280 and the connecting tube 270.

[58] The screw rod 420 shifts the melted molding material in a predetermined direction while the screw rod 420 is rotated.

[59] As described above, the gas discharge device according to the present invention externally discharges the gas generated from the melted molding material not to flow into the mold. Therefore, the way of discharging the gas according to the present invention is more effective than a conventional way that discharges the gas from a front screw end of the injection molding machine.

[60] While the present invention has been described with respect to certain preferred em-

bodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.