[CLAIMS]
[Claim 1 ] A gas discharge system of a multifunctional injection molding machine, being coupled to a raw material feeding unit having a hopper for the injection molding machine and to an inlet of a cylinder of the injection molding machine to discharge emissions generated by melting a raw material from the cylinder to an outside of the injection molding machine, comprising: an opening and closing mechanism disposed between the raw material feeding unit and the inlet of the cylinder to shield air and the raw material, the opening and closing mechanism comprising an electronic opening and closing member; a discharge mechanism comprising a discharge port and a high pressure hose near the inlet of the cylinder coupled to the opening and closing mechanism to discharge the emissions to the outside through the discharge port and high pressure hose; and a controller to control timing of opening and closing of the electronic opening and closing member and a vacuum degree of a vacuum pump.
[Claim 2] The system according to claim 1, wherein the opening and closing mechanism comprises a ball valve comprising upper and lower plates.
[Claim 3] The system according to claim 1, wherein the opening and closing mechanism has a curtain extending downward from the lower plate of the ball valve to define an emission waiting space between a wall of the inlet of the cylinder and the curtain.
[Claim 4] The system according to claim 1, wherein the opening and closing mechanism comprises a double discharge pipe extending from a lower end thereof, and comprising an injection pipe and an emission waiting space.
[Claim 5] The system according to claim 4, wherein the double discharge pipe has a suction port formed therein, and further comprises an electronic opening and closing valve for the suction port.
[Claim 6] The system according to claim 1, wherein the discharge port is connected to the high pressure hose to allow the emissions to be discharged through the discharge port and high pressure hose by means of the vacuum pump, and has a filter positioned at an entrance of the discharge port.
[Claim 7] The system according to claim 1, wherein the discharge port comprises one of a discharge port formed on a front surface of the cylinder, a discharge port formed on a side surface of the inlet of the cylinder, and a discharge port formed perpendicular to the inlet of the cylinder.
[Claim 8] The system according to claim 1, wherein the discharge port comprises discharge ports formed on a front surface of the cylinder and at a predetermined location near the inlet of the cylinder while being connected to each other by the high pressure hose, and a switch valve disposed at a connection between the discharge ports to allow the emissions to be discharged through one of the discharge ports selected by the switch valve.
[Claim 9] The system according to claim 1, wherein the controller comprises a vacuum pump controller to control the electronic opening and closing member to open and close the ball valve, and operation and vacuum degree of the vacuum pump, an injection molding signal input section to set a time for an overall operation of the molding machine, to control start and end of the molding machine and to control a selective operation of the molding machine, and an emission discharge controller to control discharge of the emission. |
[DESCRIPTION] [Invention Title]
GAS DISCHARGE SYSTEM OF INJECTION MOLDING MACHINE
[Technical Field]
The present invention relates to a gas discharge system of an injection molding machine, and, more particularly, to a gas discharge system of an injection molding machine, which forces an unnecessary gas generated upon production of a molded product to be discharged to an outside of the injection molding machine via a vacuum pump during a process wherein raw materials (plastic powders, grains, etc.) supplied into a cylinder of the molding machine are sliced and melted at the same time via heat and physical friction in a compression section of the cylinder, completely melted in a melting section of the cylinder, and then finally compressed forward by a screw of the cylinder, thereby improving quality of the molded product.
[ Background Art ]
With an improvement in the field of raw material processing and molds, there have been rapid advance in injection molding technology, which results in an increasing demand of the market for products having various and higher precision. For injection molding, after preparing cylindrical or rectangular chips having a size of several millimeters and formed of a plastic raw material such as styrene, polyvinyl chloride, polypropylene resins, etc. containing pigment, stabilizer, plasticizer, fillers, etc., that is, compounds of the plastic raw materials, in a hopper, the compounds are supplied to a cylinder through an input port thereof, and heated at high pressures by a heating chamber in front of the input port, forming a molten resin for the injection molding. Then, the molten resin is injected into a mold by means of a screw in the cylinder. After the molted resin
is solidified within the mold, the mold is divided into two sections, and then an injection molded product is ejected from the mold. As such, the products are produced in a large amount by repeating the injection molding as described above.
Although a conventional injection molding machine can produce an item in mass production through injection molding, it has a problem in that a gas generated from the molten material during the injection molding causes defective appearances of the item such as burnt marks, weld lines, bubbles, etc., and an increase in frequency of defective products during post processes, such as painting, plating, coating, deposition, etc.
[Disclosure]
[Technical Problem]
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a gas discharge system of an injection molding machine, which can effectively discharge a gas generated in a cylinder of the injection molding machine to an outside of the injection molding machine, which is not efficiently discharged due to infiltration of external air in the conventional injection molding machine.
It is another object of the present invention to provide the effective gas discharge system, which comprises a ball valve to improve an opening and closing rate for fluid and air, and, if necessary, comprises the ball valve with an electronic opening and closing unit, thereby enabling highly efficient production of products, installation of the gas discharge system at low cost, and convenient maintenance thereof.
It is yet another object of the present invention to provide the effective gas discharge system, which is designed to selectively employ an electric control method (for completely automatic opening and closing of the ball valve, partially automatic operation of the ball valve, and manual operation of the ball valve) and a simple mechanical method, enabling the highly efficient production of products, installation of the system at low cost, and the convenient
maintenance thereof.
It is yet another object of the present invention to provide the effective gas discharge system, which comprises an electronic opening and closing unit disposed near an inlet of the cylinder to allow any one of vacuum discharge, suction discharge, and vacuum-suction combined discharge to be selectively applied to the injection molding machine, thereby enabling discharge of the unnecessary gas from the cylinder to the outside to be performed in various ways.
[Technical Solution]
In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a gas discharge system of an injection molding machine, being coupled at an upper surface to a raw material feeding unit of the injection molding machine, and at a bottom surface to the injection molding machine to discharge air and emissions generated by melting a raw material from the cylinder to an outside of the injection molding machine, comprising: an opening and closing mechanism disposed between the raw material feeding unit and an inlet of a cylinder of the molding machine through which the raw material is supplied from the raw material feeding unit to the cylinder, and including a ball valve to improve a closing force between upper and lower plates of the opening and closing mechanism; and a controller comprising an electronic opening and closing member connected to the ball valve to control timing of opening and closing of the opening and closing mechanism, and a vacuum degree of a vacuum pump to allow vacuum discharge. The gas discharge system may further comprise a discharge port and a discharge mechanism disposed at a lower end of the opening and closing mechanism.
The gas discharge system may further comprise other discharge ports formed directly on a front surface of the cylinder or on a position near the inlet
of the cylinder to discharge the emissions.
[Advantageous Effects]
As apparent from the above description, the gas discharge system of the injection molding machine has an excellent effect in discharging of emissions generated in a cylinder of the molding machine to the outside.
Moreover, the gas discharge system of the invention comprises a ball valve of a simple configuration, which can actively promote vacuum discharge of the emissions by increasing a vacuum degree of a vacuum pump, thereby improving the quality of the injection molded product by reduction in frequency of defective products, and enabling easy installation of the gas discharge system at low costs.
[Description of Drawings]
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a sectional side elevation view of a gas discharge system of a functional injection molding machine according to a preferred embodiment of the present invention;
Fig. 2 is a sectional side elevation view of a ball valve of an opening and closing mechanism of the gas discharge system, showing an open state of the ball valve;
Fig. 3 is a perspective view of the opening and closing mechanism of the gas discharge system;
Fig. 4 is a circuit diagram illustrating one embodiment of a controller of the gas discharge system;
Fig. 5 is a constructional view of a double discharge pipe and a ball valve of a gas discharge system according to another embodiment of the present
invention, showing an open state of the ball valve;
Fig. 6 is a view showing the ball valve in a closed state;
Fig. 7 is a sectional side elevation view of a gas discharge system comprising a vacuum sensor according to yet another embodiment of the present invention;
Fig. 8 is a constructional view illustrating a suction port and a discharge port connected to the double discharge pipe of the gas discharge system; and
Figs. 9, 10 and 11 are sectional side elevation views of a gas discharge system according to other embodiments of the present invention, showing various discharge ports formed near an inlet of a cylinder of the injection molding machine.
[Best Mode]
Preferred embodiments of the present invention will be described hereinafter with reference to the drawings. Referring to Figs. 1 to 11, a gas discharge system of an injection molding machine according to the present invention is provided with a hopper on an upper surface of the discharge system, and comprises an opening and closing mechanism 200 positioned under a lower surface thereof between the discharge system and the molding machine to create a vacuum state so as not to allow infiltration of external air by completely shielding a raw material feeding unit 20 which serves to feed a raw material 10, and to force air and emissions within a cylinder of the molding machine to be discharged to an outside through a discharge port 80 by means of a vacuum pump 130. Here, the gas discharge system of the invention comprises a ball valve 50 to achieve a shielding function with respect to the outside, and to permit smooth operation of the opening and closing mechanism with an increased closing force.
With the gas discharge system of the present invention, the injection molding machine is operated in such a way that, while being supplied into a cylinder of the injection molding machine, raw materials (plastic powders,
grains, etc.) are sliced and melted at the same time via heat and physical friction in a compression section of the cylinder, completely melted in a melting section of the cylinder, and then are finally compressed forwards by a screw, forcing air and emissions within the cylinder to be discharged to the outside, thereby reducing frequency of defective products due to an unnecessary gas generated during compression of the screw. In this regard, the raw material feeding unit is provided with the ball valve 50 which shields the infiltration of external air into the cylinder while discharging the air and emissions of the cylinder to the outside by means of the vacuum pump 130. The opening and closing mechanism 200 has an upper plate 30 secured to the raw material feeding unit 20 by means of bolts and nuts 70, and a lower plate 40 secured to an inlet of the cylinder 100 by means of other bolts and nuts 70.
Since the opening and closing mechanism 200 allows the lower plate to be replaced with new one corresponding to a size of the inlet of the cylinder if the size of the inlet of the cylinder varies according to a kind of injection molding machine, the gas discharge system of the present invention has a high compatibility without any restriction of the kind of injection molding machine.
The ball valve 50 is positioned between the upper and lower plates 30 and 40 to increase the closing rate as much as possible by shielding the external air. The ball valve comprises a penetrated ball positioned at a center of a passage through which the raw material flows, and capable of being rotated at 90 degrees by the handle and stem of the valve positioned at the right angle with respect to the passage, thereby enabling complete opening and closing of the passage.
According to one embodiment, the gas discharge system further comprises an electronic opening and closing member 60 provided to the ball valve to automatically open and close the ball valve, and a controller 140 to control overall operation of supplying the raw material and closing the ball valve. A discharge mechanism 150 comprises the discharge port 80 formed near the inlet 90 of the cylinder couple to the opening and closing mechanism, and a
high pressure hose 110, which is connected at one end to the discharge port and at the other end to the vacuum pump 130, and through which the emissions are discharged to the outside.
The discharge port 80 is formed at a side surface corresponding to the ball valve, and has a filter positioned at an entrance of the discharge port 80 to prevent the raw material from being discharged along with the emissions.
The discharge port 80 is connected to the vacuum pump via the high pressure hose, and the vacuum pump is provided at an inlet thereof with a filter 120 to filter foreign substances and harmful gases. The controller 140 controls not only an operation cycle and timing of the electronic opening and closing member 60 provided to the ball valve, but also pressure of the vacuum pump upon vacuum discharge.
The vacuum pump and the controller may be placed in separate boxes at the outside or integrated to a side of the injection molding machine. Referring to Fig. 4, the controller of the invention serves to control suction of air by opening and closing the raw material feeding unit 20, and to allow a gas generated in the cylinder to be discharged during an overall operation period or a partial operation period of the injection molding machine, thereby enabling the gas to be efficiently discharged to the outside. For this purpose, the controller is constructed as follows.
The controller 140 comprises a vacuum pump controller 140-3 to control an operation of the electronic opening and closing member 60 of the ball valve, for example, opening or closing of the ball valve 50, and an operation of the vacuum pump 130, such as vacuum degree, start and stop of the vacuum pump, and an injection molding signal input section 140-1 to select and control the overall or partial operation cycle of the injection molding machine.
The injection molding machine is operated in order of mold closing — * mold closing finishing — * nozzle forward → injecting — > metering —> nozzle backward — > cooling — » mold opening -* ejecting in one operation cycle, and the control is performed on the base of the operation.
For gas discharge during the overall operation cycle of the injection
molding machine, first, Signal 1 is input from the injection molding signal input section 140-1 to a full-automatic injection molding section, and Signal 2 is input from the injection molding signal input section 140-1 to a metering section. If the injection molding machine is operated in response to the input signal for full- automatic injection molding, an electromagnetic relay Rl becomes ON in response to Signal 1, and in turn, an electromagnetic relay R3 becomes ON. When the electromagnetic relay R3 becomes ON, Ml of the vacuum pump controller 140-3 becomes ON, so that the vacuum pump 130 starts to operate, allowing the gas discharge to be started. At this time, although the raw material feeding unit 20 is blocked by the raw materials, external air is sucked into a raw material pouring pipe, and the gas discharge is performed at a mild level. With start of a metering operation during which most of emissions is generated during operation of the injection molding machine, an electromagnetic relay R2 becomes ON in response to Signal 2 from the injection molding signal input section 140-1, and then, SOLI of the electronic opening and closing member 60 of the ball valve 50 is immediately operated to close the ball valve 50 which is usually in an open state, thereby preventing suction of air into the raw material feeding unit 20. As a result, a space under the ball valve 50 is converted to a vacuum state, enabling the emissions in the cylinder to be forcibly discharged to the outside. After a predetermined period of time Tl is elapsed from finish of the metering operation, the electronic opening and closing member 60 is turned off, and the raw material is supplied into the cylinder, while waiting for a next metering operation.
For gas discharge during the partial operation cycle of the injection molding machine, first, Signal 1 is input from the injection molding signal input section 140-1 to an injection molding machine operating section, and Signal 2 is input from the injection molding signal input section 140-1 to the metering section. Then, an electromagnetic relay R3 of an emission discharge controller 140-2 becomes ON only upon the injection and metering operations, and the vacuum pump controller 140-3 also becomes ON only upon the injection and metering operations, so that the vacuum pump 130 starts to discharge the emissions only upon the injection molding and metering operations. At this
time, the ball valve 50 is operated only upon the metering operation as in the above operation, thereby preventing the suction of air into the raw material feeding unit 20. As such, the vacuum pump 130 and the ball valve 50 are repetitiously operated only upon the injection and metering operations. After closing the raw material feeding unit, the vacuum pump is activated to discharge interior air and emissions to the outside, with the ball valve ensured to completely close the passage of the raw material.
In Figs. 5 and 8, a gas discharge system of the injection molding machine according to another embodiment of the invention is shown. The gas discharge system of this embodiment is coupled at an upper surface to the raw material feeding unit 20 and at a lower surface to the inlet of the cylinder of the machine. The gas discharge system comprises a ball valve 50 positioned at an upper portion of the system to increase a closing degree by preventing the raw material and air from entering the gas discharge system so as to improve molding precision by discharging emissions generated in the cylinder to the outside, and a double discharge pipe 190 positioned at a lower end of the ball valve and constituted by a double pipe 160 comprising an injection pipe 170 and an emission waiting space 180, both of which extend from the lower end of the ball valve.
The double discharge pipe 190 comprises an upper plate 30-1 and a lower plate 30-2 respectively secured to associated components by means of bolts and nuts 70 or welding, with the double pipe 160 disposed at a center of the double discharge pipe 190. The injection pipe 170 extends below the lower plate 30-2, and forms a curtain protruding from a lower end of the lower plate 30-2 such that the injection pipe 170 is deeply inserted into the inlet of the cylinder. The emission waiting space 180 of the double discharge pipe 190 is formed with a discharge port, which is connected to the vacuum pump 130 via the high pressure hose 110 to allow the emissions generated in the cylinder to be discharged to the outside therethrough.
According to this embodiment, the gas discharge system may further comprise a vacuum sensor 150, as shown in Fig. 7, to monitor and control a vacuum degree in a state wherein the ball valve 50 is closed. Compared with a
conventional technique which has difficulty in monitoring of the vacuum degree, the gas discharge system of the invention comprises the vacuum sensor 150 which enables easy monitoring and control of the vacuum degree in the discharge system, thereby helping to improve quality of products while reducing power consumption.
According to yet another embodiment, the gas discharge system may further comprise a suction port 100-2 to control suction and shielding of external air, and an electronic opening and closing valve 60-1 provided to the double discharge pipe 190 to automatically open and close the suction port, as shown in Fig. 8.
Specifically, the suction port is formed at one side of the double pipe 160 to supply a minute amount of air into the emission waiting space 180 or to shield the air from entering there. In addition, the discharge port 80 is formed at the other side thereof to discharge the air and emissions to be discharged to the outside.
According to other embodiments, the gas discharge system is selectively formed with one of a first discharge port 80 at a side of the inlet of the cylinder, a second discharge port 80-2 perpendicular to the inlet of the cylinder, and a third discharge port 80-1 on a front surface of the cylinder, as shown in Figs, 9 to 11. With this configuration, the emissions of the cylinder 100 can be discharged to the outside through the discharge port 80, 80-1 or 80-2 directly formed to the cylinder, thereby improving discharge efficiency of the system.
As such, when the gas discharge system comprises the separate discharge port 80, 80-1 or 80-2, it is possible to constitute the discharge port 80, 80-1 or 80- 2 so as to be connected with the vacuum pump 130 to discharge the emissions to the outside via the vacuum pump 130. Meanwhile, it is desirable that the discharge port 80-2 be positioned at a location closest to the inlet of the cylinder so as to prevent the raw material from being discharged along with emissions through the discharge port 80-2, when forming the discharge port 80-2 perpendicular to the cylinder, as shown in Fig. 9, thereby ensuring easy operation and convenience discharge of the emissions before the raw material is melted.
Alternatively, with the first and third discharge ports formed at the side of the inlet of the cylinder and on the front surface of the cylinder, respectively, the gas discharge system may further comprise a switch valve 160-1 disposed at a connection between the first and third discharge ports to allow the emissions to be discharged in a direction selected by means of the switch valve 160- 1.
With this construction, the emissions generated in the cylinder and air induced thereinto from the exterior can be completely discharged to the outside in an optimal state.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
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