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, June 2011, Pages 740–7548th International Symposium on Engineering Turbulence Modelling and Measurements, Marseille, France,June 9 to 11, 2010 — Engineering Turbulence Modelling and MeasurementsEdited By Suad Jakirlic and Tom Gatski
Hydrodynamic and thermal fields analysis in gas&solid two-phase flow, , , , , , , , a Faculty of Engineering, Menoufiya University, Shebin El-kom, Egyptb Faculty of Engineering, Kafrelsheikh, University, Kafrelsheikh, EgyptThe present work aims to investigate numerically the flowfield and heat transfer process in gas&solid suspension in a vertical pneumatic conveying pipe. The Eulerian&Lagrangian model is used to simulate the flow of the two-phases. The gas phase is simulated based on Reynolds Average Navier&Stokes equations (RANS) with low Reynolds number k&ε model, while particle tracking procedure is used for the solid phase. An anisotropic model is used to calculate the Reynolds stresses and the turbulent Prandtl number is calculated as a function of the turbulent viscosity. The model takes into account the lift and drag forces and the effect of particle rotation as well as the particles dispersion by turbulence effect. The effects of inter-particles collisions and turbulence modulation by the solid particles, i.e. four-way coupling, are also included in the model. Comparisons between different models for turbulence modulation with experimental data are carried out to select the best model. The model is validated against published experimental data for velocities of the two phases, turbulence intensity, solids concentration, pressure drop, heat transfer rates and Nusselt number distribution. The comparisons indicate that the present model is able to predict the complex interaction between the two phases in non-isothermal gas&solid flow in the tested range. The results indicate that the particle&particle collision, turbulence dispersion and lift force play a key role in the concentration distribution. In addition, the heat transfer rate increases as the mass loading ratio increases and Nusselt number increases as the pipe diameter increases.KeywordsGas&solid; Heat transfer; Particle&particle collision; Four-way coupling; CFD
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No articles found.GAS EXHAUSTING DEVICE OF CYLINDER FOR INJECTION MOLDING
WIPO Patent Application WO/
A gas exhausting device of a cylinder for injection molding is disclosed. The gas
exhausting device includes a main body (110), a filter unit (120) and an air supply
control unit (130). The main body (110) includes a body block (111), which has
a material inlet (111a), a gas outlet (111b), an air injection passage (111c), an
outside air inlet passage (111d) and a cavity (E1). The main body further includes a
material input pipe (112), which communicates with the material inlet of the body
block, and an air blower (113), which is connected to the cavity and the air injection
passage of the body block. The main body further includes an outside air inlet
pipe (114), which is connected to the outside air inlet passage, and a filter-equipped
socket (115), which is coupled to the outside air inlet passage.
Inventors:
MUN, Kwang Pil (Kurim Villa 201-ho, 96-12 Wa-dongDanwon-gu, Ansan 425-840, KR)
Application Number:
Publication Date:
01/31/2008
Filing Date:
07/06/2007
Export Citation:
MUN, Kwang Pil (Kurim Villa 201-ho, 96-12 Wa-dongDanwon-gu, Ansan 425-840, KR)
International Classes:
View Patent Images:
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Foreign References:
Attorney, Agent or Firm:
HWANG, Sun-Woong (202 Shinwon Plaza, 681-3 Gojan-dongDanwon-gu, Ansan 425-020, KR)
[1] A gas exhausting device of a cylinder for injection molding, comprising a main body provided between a material input hopper and the cylinder of an injection molding machine, the main body having a gas exhausting structure such that gas is guided and exhausted outside the cylinder using air pressure, a filter unit coupled to the main body and guiding inflow of the exhausted gas thereinto using air pressure, the filter unit filtering the gas, exhausted from the cylinder, through a double filtering process, and having an anti-noise function, and an air supply control unit controlling application of air pressure to the main body and the filter unit to induce exhaustion of the gas from the cylinder, wherein the main body comprises: a body block having a material inlet and a gas outlet at a central portion in respective upper and lower ends thereof, with an air injection passage and an outside air inlet passage formed at predetermined positions in a sidewall of the body block, and a cavity defin a material input pipe communicating with the material inlet of the body block and placed upright, the material input pipe extending a
an air blower protruding from the sidewall of the body block and connected to the cavity and the air injection passa an outside air inlet pipe provided on an outside surface of the material input pipe and connected to the outside air inlet passage, with a plurality of pores formed through a bottom of the ou and a filter-equipped socket coupled to the outside air inlet passage to remove foreign substances such as dust from air drawn from outside.
[2] The gas exhausting device according to claim 1, wherein the filter unit comprises: a first filtering part having therein a gas inflow passage, through which gas, exhausted from the main body by air pressure, is drawn into the first filtering part, with a primary filter provided in the gas inflow passage, the first filtering part further having therein a gas moving passage, through which primarily- filtered gas flows, and an a and a second filtering part having therein an air blower connected to the gas moving passage and the air injection passage of the first filtering part, with a soundproof panel provided on a sidewall of the second filtering part which is opposite the air blower, and a plurality of secondary filters provided in the second filtering part to secondarily filter the primarily-filtered gas drawn through the air blower and absorb/remove noise.
[3] The gas exhausting device according to claim 1, wherein the air supply control unit includes, in a casing thereof, a main supply pipe and at least two branch pipes branching from the main supply pipe, wherein one of the branch pipes is connected to the air injection passage of the main body, a remaining one of the branch pipes is connected to the air injection passage of the filter unit, and solenoid controlled on/off valves are provided on the respective branch pipes and are connected to a relay that receives a control signal from a main controller of the injection molding machine.
[4] The gas exhausting device according to claim 1, wherein the body block has a bottom surface inclined downwards, so that input material and dust move downwards along the inclined bottom surface of the body block and are thus prevented from remaining in the block body.
[5] The gas exhausting device according to claim 1, wherein the material input pipe is installed such that a distance between an end thereof and an upper surface of a screw, provided in the cylinder of the injection molding machine, is within a range from 10mm to 15mm.
[6] The gas exhausting device according to claim 1 or 2, wherein the air blower comprises a body having a pipe shape and defining a through hole therein, with an air injection hole formed around a rim of a rear end of the body of the air blower, and a plurality of air passing holes formed in the body of the air blower and extending from the air injection hole to form an air stream flowing from the air injection hole towards a front end of the through hole.
[7] The gas exhausting device according to claim 2, wherein the primary filter comprises has a gas detecting filter, which has an external structure that is exposed outside and is provided with a cover, the gas detecting filter filtering gas and changing color when exposed to the gas such that a user checks a gas exhausting state with a naked eye, and the secondary filters are placed upright in the second filtering part, and each of the secondary filters comprises a hollow filter socket, through a circumferential sidewall of which a plurality of holes is formed, and a carbon filtering member provided on an inner surface of the sidewall of the filter socket.
[8] The gas exhausting device according to claim 2, wherein the soundproof panel has an egg tray shape and is made of sponge or foamed urethane.
Description:
Description GAS EXHAUSTING DEVICE OF CYLINDER FOR INJECTION MOLDING Technical Field [1] The present invention relates, in general, to devices for exhausting gas from cylinders of injection molding machines which are used to extrude material, and, more particularly, to a gas exhausting device of a cylinder for injection molding which exhausts gas, generated in the cylinder of an injection molding machine, using air pressure, and is constructed such that the gas exhausting operation is conducted in conjunction with the injection molding machine only when the injection molding machine is operated, thus enhancing the working efficiency of the gas exhausting device as well as the efficiency with which gas is exhausted. Background Art [2] Generally, injection molding is a molding method in which synthetic resin material is input into a cylinder of an injection molding machine and is heated to form softened plastic material and, thereafter, the heat-softened plastic material is forced into a mold, thus forming a plastic product. [3] However, during the injection molding process, that is, when material is input into the cylinder, heated to form softened plastic material, and forced into the mold, gas is generated from the heat-softened plastic material in the cylinder. The gas generated in the cylinder enters the mold when the heat-softened plastic material is forced into the mold. [4] As such, in the case where gas generated in the cylinder enters the mold, there is a problem of a defective product in that the external appearance thereof is deteriorated due to the gas. [5] To avoid the above-mentioned problem, during the injection molding process, gas generated in the cylinder must be exhausted outside to prevent the gas from remaining in the mold. For this, a gas exhausting device and structure for injection molding was developed. [6] However, in the conventional gas exhausting device and structure, the exhaustion of gas is not satisfactorily achieved, that is, gas is not smoothly exhausted for reasons such as backflow. In other words, there is a problem in that gas exhausting efficiency is low, so that it is difficult to produce high-quality products and ensure the reliability of the products. [7] Furthermore, in the conventional art, because the gas exhausting efficiency is low, it is very difficult to form products, such as precision components, thin films or lens, which require strict molding conditions. Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a gas exhausting device of a cylinder for injection molding which exhausts gas, generated in the cylinder of an injection molding machine, using air pressure, and is constructed such that the gas exhausting operation is conducted in conjunction with the injection molding machine only when the injection molding machine is operated, thus enhancing the working efficiency of the device as well as the efficiency with which gas is exhausted. [9] Another object of the present invention is to provide a gas exhausting device of the cylinder for injection molding which can markedly reduce the defective proportion of products and form pure products, and makes it possible to form products, such as precision components, thin films, or lens, which cannot be produced in the conventional arts, thus extending the field of application of injection molding. [10] A further object of the present invention is to provide a gas exhausting device of the cylinder for injection molding which improves the circumstances of a site for injection molding, and in which, because the mold is prevented from being contaminated by gas, the mold can be maintained clear, so that the repair and maintenance cost of the mold is reduced. Technical Solution [11] In order to accomplish the above objects, the present invention provides a gas exhausting device of a cylinder for injection molding, including a main body provided between a material input hopper and the cylinder of an injection molding machine, the main body having a gas exhausting structure such that gas is guided and exhausted outside the cylinder using air pressure, a filter unit coupled to the main body and guiding inflow of the exhausted gas thereinto using air pressure, the filter unit filtering the gas, exhausted from the cylinder, through a double filtering process, and having an anti-noise function, and an air supply control unit controlling application of air pressure to the main body and the filter unit to induce exhaustion of the gas from the cylinder, wherein the main body comprises: a body block having a material inlet and a gas outlet at a central portion in respective upper and lower ends thereof, with an air injection passage and an outside air inlet passage formed at predetermined positions in a sidewall of the body block, and a cavity defin a material input pipe communicating with the material inlet of the body block and placed upright, the material input pipe extending a
an air blower protruding from the sidewall of the body block and connected to the cavity and the air injection passa an outside air inlet pipe provided on an outside surface of the ma terial input pipe and connected to the outside air inlet passage, with a plurality of pores formed through a bottom of the ou and a filter-equipped socket coupled to the outside air inlet passage to remove foreign substances such as dust from air drawn from outside. Advantageous Effects [12] The present invention provides a gas exhausting device of a cylinder for injection molding which has a structure such that gas can be exhausted from the cylinder using air pressure, and a gas exhausting and filtering process is conducted only when the injection molding machine is operated. The gas exhausting device of the present invention has advantages in that the efficiency with which gas is exhausted can be increased, the device is prevented from malfunctioning, and working efficiency of the device is increased. [13] Furthermore, the present invention can prevent material from being contaminated when the kind of material is changed, thus markedly reducing the defective proportion of products and making it possible to form pure products. In addition, the present invention makes it possible to form products, such as precision components, thin films or lens, thus enhancing the usefulness thereof. As such, the present invention is advantageous in that the field of application is broad. [14] Moreover, in the present invention, exhaust gas can be filtered, and the filtering efficiency is superior, thus improving the circumstances of a site for injection molding. Furthermore, because the inflow of gas into a mold is minimized, the mold is prevented from being contaminated by gas, so that the mold can be maintained clear, and the repair and maintenance costs of the mold are reduced. In addition, the present invention has an advantage in that a user can easily check with the naked eye whether gas is normally exhausted. Brief Description of the Drawings [15] FIG. 1 is a view showing the use of a gas exhausting device of a cylinder for injection molding, according to an embodiment of t [16] FIG. 2 is a schematic view showing the construction of the gas exhausting device according to t [17] FIG. 3 is a front view of the gas exhausting device of FIG. 2; [18] FIG. 4 is a view showing a material input pipe and an outside air inlet pipe of the gas exhausting device according to t [19] FIG. 5 is a partial sectional view showing a second filtering part of the gas exhausting device according to t [20] FlG. 6 is a detailed sectional view showing an air blower of the gas exhausting device according to t and [21] FlG. 7 is a detailed sectional view showing a secondary filter of the gas exhausting device according to the present invention. Best Mode for Carrying Out the Invention [22] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. [23] FlG. 1 is a view showing the use of a gas exhausting device of a cylinder for injection molding, according to the embodiment of the present invention. FlG. 2 is a schematic view showing the construction of the gas exhausting device. FlG. 3 is a front view of the gas exhausting device of FlG. 2. FlG. 4 is a view showing a material input pipe 112 and an outside air inlet pipe 114 of the gas exhausting device. FlG. 5 is a partial sectional view showing a second filtering part 120 of the gas exhausting device. FlG. 6 is a detailed sectional view showing an air blower 113 of the gas exhausting device. FlG. 7 is a detailed sectional view showing a secondary filter 122c of the gas exhausting device. [24] As shown in FIGS. 1 through 7, the gas exhausting device of the cylinder for injection molding according to the embodiment of the present invention includes a main body 110, which is provided between a material input hopper 1 and the cylinder 2 of an injection molding machine and has a gas exhausting structure such that gas can be exhausted from the cylinder 2 using air pressure, and a filter unit 120, which is coupled to the main body 110 and guides the flow of exhausted gas thereinto using air pressure. In addition, the filter unit 120 filters gas, exhausted from the cylinder 2, through a double filtering process, and has an anti-noise function. The gas exhausting device further includes an air supply control unit 130, which controls the supply of air pressure to the main body 110 and the filter unit 120 to induce the exhaustion of gas from the cylinder 2, and, in detail, performs control such that only when the injection molding machine is operated is air supplied. [25] The main body 110 includes a body block 111, which has a material inlet Ilia and a gas outlet 11 Ib at the central portion in respective upper and lower ends thereof. Furthermore, an air injection passage 111c and an outside air inlet passage 11 Id are formed at predetermined positions in the sidewall of the body block 111. In addition, the body block 111 has a cavity El therein. The main body 110 further includes the material input pipe 112, which is placed upright, communicates with the material inlet 11 Ia of the body block 111, and extends a predetermined length. The main body 110 further includes an air blower 113, which protrudes from the sidewall of the body block 111 and is connected to the cavity El and the air injection passage 111c, and the outside air inlet pipe 114, which is vertically provided on the outside surface of the material input pipe 112 and is connected to the outside air inlet passage 11 Id. In addition, a plurality of pores 114a is formed through the bottom of the outside air inlet pipe 114. The main body 110 further includes a filter-equipped socket 115, which is coupled to the outside air inlet passage 11 Id to remove foreign substances, such as dust, from air drawn from the outside. [26] Here, preferably, the body block 111 of the main body 110 is constructed such that the bottom surface 11 Ie thereof is inclined downwards, so that input material and dust are prevented from remaining in the block body 111, which is undesirable. Therefore, when one kind of input material is changed into another, the material which was input before the material was changed is prevented from remaining and mixing with the new material, thus preventing the contamination of products and the incidence of defective products. Furthermore, the body block 111 can be manufactured into various shapes, for example, into a circular, rectangular or hexagonal shape. [27] Preferably, the material input pipe 112 is installed such that the distance between an end thereof and a screw 3 of the cylinder 2 is within a range from 10mm to 15mm in order to increase the efficiency with which gas is exhausted. In the case where the material input pipe 112 is too long, so that the distance between it and the screw 3 is 10mm or less, friction occurs between the input material and the material input pipe 112, which can create a dangerous condition. In contrast, if the material input pipe 112 is too short, so that the distance between it and the screw 3 is 15mm or more, space for exhausting gas may be interrupted by the input material. [28] The air blower 113 comprises a body 113a, which has a pipe shape and a through hole E2 defined therein. An air injection hole 113b, which is connected to the air injection passage 11 Ic, is formed around the rim of the rear end of the body 113a. Furthermore, a plurality of air passing holes 113c is formed in the body 113a to form an air stream that flows from the air injection hole 113b towards the front end of the through hole E2. [29] Here, the through hole E2 of the air blower 113 communicates with the cavity El defined in the body block 111. [30] The outside air inlet pipe 114 has the bottom surface. In addition, several pores 114a are formed through the bottom surface of the outside air inlet pipe 114, so that outside air alone can be supplied into the cylinder to smoothly exhaust gas from the cylinder, while the input material is prevented from being caught in the outside air inlet pipe 114. [31] The filter unit 120 includes a first filtering part 121, which has a gas inflow passage 121a, through which gas, exhausted from the main body 110 by air pressure, is drawn into the filter unit 120. A primary filter 121b is installed in the gas inflow passage 121a. The first filtering part 121 further has a gas moving passage 121c, through which gas that is primarily filtered flows, and an air injection passage 121d. The filter unit 120 further includes a second filtering part 122, which has therein an air blower 122a that is connected to the gas moving passage 121c and the air injection passage 121d of the first filtering part 121. Furthermore, a soundproof panel 122b is provided on a sidewall of the second filtering part 122 which is opposite the air blower 122a. The second filtering part 122 further has therein a plurality of secondary filters 122c, which secondarily filter the primarily-filtered gas that is drawn through the air blower 122a and also serve to absorb/remove noise. [32] Here, the air blower 122a of the second filtering part 122 has the same construction as the air blower 113 of the main body 110. Therefore, in the explanation of the air blower 122a, the components of the air blower 122a will be designated by reference numerals in parentheses, as shown in FIG. 6. The gas moving passage 121c of the first filtering part 121 communicates with a through hole E3 of the air blower 122a, and the air injection passage 121d of the first filtering part 121 is connected to an air injection hole 22 of the air blower 122a. [33] The primary filter 121b has an external structure such that it is exposed outside, and is provided with a cover C. Furthermore, the primary filter 121b comprises a gas detecting filter that changes color when it is exposed to gas. Thus, as well as filtering gas, the primary filter 121b makes it possible for a user to easily check with the naked eye whether gas is normally exhausted. [34] The secondary filters 122c are placed upright in the second filtering part 122. Each secondary filter 122c includes a hollow filter socket 31, through the circumferential sidewall of which a plurality of holes 31a is formed, and a carbon filtering member 32, which is provided on the inner surface of the sidewall of the filter socket 31. [35] Preferably, the soundproof panel 122b has an egg tray shape and is made of sponge or foamed urethane. Of course, it will be easily understood that the soundproof panel 122b can be made of one of selected from other soundproof material, sound insulation material or sound absorption material. [36] Furthermore, an air flow rate control valve (not shown) is coupled to the air injection passage 11 Ic of the main body 110. Thus, the flow rate of air supplied into the air injection passage 11 Ic of the main body 110 is controlled by the air flow rate control valve, so that air and gas, which are drawn from the main body 110 into the filter unit 120, can be smoothly exhausted outside without flowing backwards. In detail, the air flow rate control valve is controlled such that the pressure of air supplied to the air injection passage 111 of the main body is less than the pressure of air supplied into the air injection passage 121d of the filter unit 120, so that the gas in the cylinder and air, which induces the exhaustion of the gas, can smoothly flow from the main body 110 to the filter unit 120. [37] The air supply control unit 130 includes, in a casing 131 thereof, a main supply pipe 132 and two branch pipes 133, which branch from the main supply pipe 132. One of the branch pipes 133 is connected to the air injection passage 11 Ic of the main body 110, and the other branch pipe 133 is connected to the air injection passage 121d of the filter unit 120. A solenoid controlled on/off valve 134 is provided on each branch pipe 133. The solenoid controlled on/off valves 134 of the branch pipes 133 are connected to a relay 135 and are thus controlled such that air is supplied only when the injection molding machine is operated. Here, the relay 135, which transmits on/off signals to the solenoid controlled on/off valves 134, is connected to and controlled by a main controller (not shown) of the injection molding machine. [38] Furthermore, a detecting sensor 141 is fastened to the body block 111 of the main body 110 and detects the input rate of material so that the air supply control unit 130 can control the amount of input material. The detecting sensor 141 is designed such that a detecting signal thereof is transmitted to the air supply control unit 130. In addition, a butterfly valve 142 is provided for adjusting the input rate of material using a butterfly blade 142a, which is rotated by a control command of the air supply control unit 130. The butterfly valve 142 is mounted to the material input hopper 1. [39] The operation of the cylinder gas exhausting device of the present invention, having the above-mentioned construction, will be explained herein below. [40] First, the injection molding machine is operated, and material for forming is input into the material input hopper 1. At this time, the detecting sensor 141, which is mounted to the body block 111 of the main body 110, determines the input rate of material and transmits a detecting signal to the air supply control unit 130. The air supply control unit 130 transmits a control signal to the butterfly valve 142 such that the angle at which the butterfly blade 142a is rotated is controlled to adjust the amount of input material. Furthermore, the main controller transmits a signal to the relay 135 of the air supply control unit 130 to open the solenoid controlled on/off valve 134, so that air is supplied to the main body 110 and the filter unit 120. [41] The input material is supplied into the cylinder 2, in which the screw 2 is installed, through a material input pipe 112 of the main body 110. The input material is melted in the cylinder 2 and, simultaneously, is extruded by the rotating force of the screw 3 and thus pressed into a mold (not shown) for forming products. Here, when the input material is melted in the cylinder 2, gas is generated. At this time, the gas exhausting device of the present invention sucks and forcibly exhausts gas outside the cylinder 2 using air pressure, thus rapidly removing the gas from the cylinder 2, thereby preventing the gas from entering the mold. [42] The gas exhausting principle and operation of the gas exhausting device will be explained in detail herein below. Air is supplied from the air supply control unit 130 into the air injection passages 111c and 121 of the main body 110 and the filter unit 120 under a control signal of the main controller (not shown). Here, the air supply control unit 130 is controlled such that the air supply control unit 130 is opened to supply air into the gas exhausting device only when the injection molding machine is operated. Furthermore, the air supply control unit 130 is controlled such that the air pressure supplied into the main body 110 is less than the air pressure supplied into the filter unit 120, thus preventing supplied air and exhaust gas from flowing backwards. [43] Air, which is supplied into the air injection passage 11 Ic of the main body 110, flows into the air injection hole 113b of the air blower 113 and is then exhausted into the through hole E2 through the several air passing holes 113c, thus inducing an air stream that flows to the gas inflow passage 121a of the filter unit 120. Then, gas generated in the cylinder 2 is forcibly moved upwards by the air stream and air pressure formed through the above-mentioned process and is thus drawn into the gas inflow passage 121a of the filter unit 120 via the gas outlet 11 Ib, the cavity El and the air blower 113, which communicate with each other. [44] At this time, outside air is drawn into the cylinder 2 through the outside air inlet pipe 114 of the main body 110. Thanks to the outside air drawn into the cylinder 2, gas generated in the cylinder 2 can be easily and smoothly exhausted from the cylinder 2. Here, because the filter-equipped socket 115 is provided in the path along which outside air is drawn into the cylinder 2, when outside air is drawn into the cylinder 2, foreign substances, such as dust, are eliminated from the drawn outside air. As such, because outside air is purified when it is drawn into the cylinder 2, the input material is prevented from being contaminated. [45] Meanwhile, air, which is supplied into the main body 110, and gas, which is forcibly exhausted from the cylinder 2 by the air flow, are moved along the gas inflow passage 121a of the filter unit 120 and is primarily filtered by the primary filter 121b of the first filtering part 121. Thereafter, the air and gas are guided from the first filtering part 121 to the second filtering part 122 of the filter unit 120 through the gas moving passage 121c and the air blower 122a by air supplied into the air injection passage 121d of the filter unit 120. [46] Here, the air, which is supplied into the air injection passage 121d of the first filtering part 121, is drawn into the air injection hole 22 of the air blower 122a and is exhausted into the through hole E3 through the air passing holes 23, thus creating an air stream that flows to the second filtering part 122. This air flow serves to suck gas and air, which flows from the main body 110 to the first filtering part 121, and makes it possible for the primary filter 121b to smoothly filter exhaust gas. Furthermore, in the present invention, because the primary filter 121b comprises the gas detecting filter that changes color when gas is detected, the user can easily check with the naked eye whether gas generated in the cylinder 2 is smoothly exhausted outside. [47] The primarily-filtered gas, which is drawn into the second filtering part 122 both by air supplied from the first filtering part 121 and by the operation of the air blower 122a, is secondarily filtered by the secondary filters 122c. At this time, the secondary filters 122c also serve to absorb and remove noise occurring when air pressure is applied. [48] Here, the soundproof panel 122b of the second filtering part 122, which is disposed at a position opposite the air blower 122a, first absorbs noise caused by air pressure, that is, conducts a primary noise removing or reducing function. Thanks to the constructions of the filter sockets 31 of the secondary filters 122c, resonance in the hollow space is prevented, in other words, a secondary noise removing or reducing effect is exhibited. Furthermore, because several secondary filters 122c are provided, the effect of absorbing and filtering gas is increased. In addition, the primary filter 121b and the secondary filters 122c exhibit a deodorizing effect as well as having a filtering function. [49] As such, the cylinder gas exhausting device of the present invention is constructed such that, only when the injection molding machine is operated is air pressure applied, and gas generated in the cylinder can be forcibly exhausted outside using the flow of supplied air and can be efficiently filtered. Furthermore, there are advantages in that gas exhausting efficiency is increased, malfunctions are prevented, and the defective proportion of products is markedly reduced. [50] Although the preferred embodiment of the present invention has been disclosed with reference to the attached drawings 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. Industrial Applicability [51] As described above, the gas exhausting device of the present invention is constructed such that gas is easily exhausted from the cylinder using air pressure, and a gas exhausting and filtering process is conducted only when the injection molding machine is operated. Therefore, the gas exhausting device of the present invention has advantages in that the efficiency with which gas is exhausted can be increased, malfunctions of the device are prevented, and the working efficiency of the device is increased. [52] Furthermore, as well as the function of exhausting gas from the cylinder, the present invention can prevent material from being contaminated when the kind of material is changed, thus markedly reducing the defective proportion of products and making it possible to form pure products. In addition, the present invention makes it possible to form products, such as precision components, thin films or lenses, which cannot be formed in the conventional technique, thus enhancing usefulness. As such, the present invention is advantageous in that the field of application is broad. [53] Moreover, the present invention is constructed such that exhausted gas can be filtered and the filtering efficiency is superior, thus improving the circumstances of a site for injection molding. Furthermore, because the inflow of gas into a mold is minimized, the mold is prevented from being contaminated by gas, so that the mold can be kept clean, and the repair and maintenance costs of the mold are reduced. In addition, the present invention has an advantage in that a user can easily check with the naked eye whether gas is normally exhausted.
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