CONTROL MEANS Technical Field

[1] The present invention relates to multi-nozzle-type injection-molding machines having a plurality of nozzles and, more particularly, to an injection-molding machine having a resin pressure control means, which can separately (independently) and precisely control the injection amount of respective nozzles in response to a simple manipulation by a user, thus remarkably improving the quality of injection-molded products. Background Art

[2] Generally, an injection-molding machine, which is a machine for manufacturing plastic products through injection-molding, is configured such that molten resin is injected from a resin cylinder into a manifold, and the injected resin in the manifold is evenly distributed to one or more nozzles, coupled to the lower end of the manifold, through a plurality of branching resin paths formed in the manifold, prior to being injected into a cavity of a mold, which is a forming body used for manufacturing plastic products.

[3] In the related art, nozzles of injection-molding machines are typically classified into two types of nozzles: open nozzles and valve pin nozzles, according to the open state of a gate. The open nozzle has been typically used for molding a product using high viscosity resin, which does not easily flow out of a nozzle, or has been used for producing a product that has a relatively large volume and does not require high precision. Because the gate of the open nozzle is always open, the open nozzle undesirably forms a sprue, which has a thread-like remnant and typically remains on a product, during an injection-molding process, so that a post-process for removing the sprue must be conducted after the injection-molding process. Unlike the open nozzle, the valve pin nozzle has been typically used for producing products that have relatively small volumes, high precision and high quality. The valve pin nozzle is configured such that the gate can be opened or closed by a valve pin, which is actuated vertically upwards or downwards using actuating pressure, which is hydraulic pressure or pneumatic pressure. The valve pin nozzle does not form a sprue on a product, unlike the open nozzle, so that the valve pin nozzle can produce high quality products. However, the valve pin nozzle is disadvantageous in that it increases the production cost of the machine, increases the size of the machine, and complicates the structure of the machine.

[4] However, the conventional injection-molding machine having the above-mentioned construction has a multi-nozzle structure, which comprises a plurality of nozzles coupled to the manifold, so that the conventional injection-molding machine is problematic in that it is very difficult to maintain the injection pressure of the nozzles at equal pressure. That is, to evenly distribute and feed resin to the multiple nozzles, the manifold must be provided with two or more branching resin paths therein. To form the resin paths in the manifold, a machine tool is used. However, the machining work for forming the resin paths in the manifold using a machine tool is very difficult and high precision work, thus undesirably causing variation in the dimensions of the resin paths. Similarly, the nozzles coupled to the manifold must be machined highly precisely so as to provide high dimensional precision, however, it is very difficult to machine the nozzles to provide high dimensional precision, thus causing variation in the dimensions of the resin paths.

[5] As described above, the variation in the dimensions of the resin paths formed in the manifold or of the resin orifices of the nozzles in a conventional injection-molding machine results in a problem in that the resin injection amounts of the nozzles are not even, causing the molded products of the molding machine to have bad quality due to excessive molding or premature molding. In an effort to solve the problems, an injection-molding technique has been proposed as follows. In the injection-molding technique, to produce an injection-molded product, the viscosity of resin is adjusted by controlling the temperature of the resin passing through the nozzles such that the resin has different temperatures. However, this injection-molding technique is problematic in that it causes uneven quality of molded products and increases the number of low quality products.

[6] Accordingly, the resin paths formed in the manifold and the resin orifices formed through the nozzles coupled to the manifold must be machined again to have equal diameters, however, the machining process for forming the equal diameters of the resin paths and resin orifices is a very difficult process, which consumes excessive money and excessive time. Disclosure of Invention Technical Problem

[7] 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 an injection-molding machine having a resin pressure control means, which is configured such that the diameters of resin paths can be adjusted in response to a simple manipulation by a user, thus equally precisely controlling the injection amounts of gates in multiple nozzles and improving the degree of freedom during a process of

machining the manifolds and nozzles, and improving productivity, safety and the degree of precision while the products are produced through a high precision injection- molding process. Technical Solution

[8] In order to achieve the above object, according to an embodiment of the present invention, there is provided an injection-molding machine, comprising a manifold having at least one installation hole, which is formed vertically downwards in the manifold and communicates with a resin path to inject resin into a mold, and a nozzle coupled to the installation hole of the manifold and having a resin orifice connected to a gate so as to receive the resin through the resin orifice, the injection-molding machine being characterized in that it further comprises: a resin pressure control means for variably controlling at least either the inner diameter of the resin path or the inner diameter of the resin orifice, thus controlling an amount of resin that passes through the gate, the resin pressure control means comprising: a pressure control pin vertically movably placed such that a reduced-diameter first end of the pressure control pin is placed in a predetermined position in either the resin path or the resin orifice and a second end of the pressure control pin passes through the upper end of the manifold so as to project outside the manifold; a support body placed on the upper end of the manifold, in which the pressure control pin is placed, so that the support body supports the outer circumferential surface of the second end of the pressure control pin; and a control body rotatably placed around the support body and engaging with the second end of the pressure control pin through a threaded engagement, so that the control body moves the pressure control pin vertically upwards or downwards when the control body is rotated.

[9] According to another embodiment of the present invention, there is provided an injection-molding machine, comprising a manifold having a branching resin path therein to inject resin into a mold, and a nozzle coupled to an end of the manifold and having a resin orifice communicating with a gate connected to the branching resin path, the injection-molding machine further comprising resin pressure control means, the resin pressure control means comprising: a flow control rotary pin rotatably placed in either the resin path of the manifold or the resin orifice of the nozzle such that a first end of the flow control rotary pin is placed in the resin path and forms a pipeline so as to allow the resin to pass through the pipeline and a second end of the flow control rotary pin extends to project outside the manifold, so that the flow control rotary pin variably controls an amount of resin passing through the resin path or the resin orifice; a support body placed on an end of the manifold, in which the second end of the flow control rotary pin is placed, so that the support body rotatably supports an outer cir-

cumferential surface of the second end of the flow control rotary pin; and a control bar engaging with the outer circumferential surface of the second end of the flow control rotary pin through a worm gear engagement and rotating the flow control rotary pin in either direction in response to manipulation by a user, thus controlling an opening ratio of an inlet of the pipeline.

Brief Description of the Drawings

[10] FlG. 1 and FlG. 2 are sectional views illustrating valve pin nozzle-type injection- molding machines having resin pressure control means according to the first embodiment of the present invention;

[11] FlG. 3 and FlG. 4 are sectional views illustrating open nozzle-type injection- molding machines having resin pressure control means according to the first embodiment of the present invention; [12] FlG. 5 is a sectional view illustrating an injection-molding machine having a manifold using resin pressure control means according to the first embodiment of the present invention; [13] FlG. 6 is a sectional view illustrating a valve pin nozzle-type injection-molding machine having resin pressure control means according to the second embodiment of the present invention; [14] FlG. 7 is a perspective view illustrating an important part of the resin pressure control means used in the injection-molding machine of FlG. 6; [15] FlG. 8 is a sectional view taken along line A-A of FlG. 6, and explains the operation of controlling the opening ratio executed by the resin pressure control means of FIG. 6; [16] FlG. 9 is a sectional view illustrating an open nozzle-type injection-molding machine using resin pressure control means according to the second embodiment of the present invention; [17] FlG. 10 is a perspective view illustrating an important part of the resin pressure control means used in the injection-molding machine of FlG. 9; [18] FlG. 11 is a sectional view taken along line B-B of FlG. 9, which explains the operation of controlling the opening ratio executed by the resin pressure control means of FIG. 9; [19] FlG. 12 is a sectional view illustrating an injection-molding machine having a manifold using resin pressure control means according to the second embodiment of the present invention; [20] FlG. 13 is a perspective view illustrating an important part of the resin pressure control means used in the injection-molding machine of FlG. 12; and [21] FlG. 14 is a sectional view taken along line C-C of FlG. 12, which explains the

operation of controlling the opening ratio executed by the resin pressure control means of FIG. 12.

[22] <Description of the elements in the drawing>

[23] 10 : manifold 20 : nozzle

[24] 25 : valve pin 11,21 : resin path

[25] 30 : drive unit 40 : pressure control pin

[26] 50 : support body 60 : control body

[27] 70 : flow control rotary pin 71 : pipeline

[28] 72 : worm wheel 80 : support body

[29] 90 : control bar 92 : worm

Mode for the Invention

[30] The present invention relates to an injection-molding machine having a resin pressure control means, which is a multi-nozzle-type injection-molding machine having a plurality of nozzles and is configured such that the injection amounts of the nozzles are separately and precisely controlled in response to a simple manipulation by a user, thus improving the quality of injection-molded products.

[31] Herein below, injection-molding machines having resin pressure control means according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The resin pressure control means according to the present invention may be embodied as a first embodiment and a second embodiment. FIG. 1 through FIG. 5 are drawings to illustrate the first embodiment of the present invention. The resin pressure control means according to the first embodiment of the present invention may be adapted to a valve pin nozzle, an open nozzle, or a manifold. FIG. 1 and FIG. 2 are sectional views illustrating valve pin nozzle-type injection-molding machines having the resin pressure control means according to the first embodiment of the present invention. As shown in the drawings, each of the valve pin nozzle-type injection-molding machines according to the first embodiment of the present invention comprises a manifold 10, a plurality of nozzles 20 each having a valve pin 25 to open or close a gate as the valve pin 25 is moved upwards and downwards, and a resin pressure control means.

[32] The manifold 10 is a plate-shaped metal body, with a plurality of branching resin paths 11 formed in the manifold 10 to allow molten resin to flow through the paths 11. At least one installation hole is formed vertically in the lower part of the manifold 10 such that the installation hole communicates with both the resin paths 11 of the manifold 10 and the resin orifice 21 of a nozzle 20. Furthermore, a heater (not shown) is provided in each of the upper and lower surfaces of the manifold 10 through forging so that the heater emits heat to the molten resin flowing through the resin paths 11,

thereby preventing the molten resin from hardening. The manifold 10 having the above-mentioned structure is provided with nozzles 20 below the lower surface thereof and drive units 30 above the upper surface thereof so as to actuate the valve pin 25 vertically upwards or downwards.

[33] Each of the nozzles 20 is a tubular longitudinal member, with a resin orifice 21 formed through the central axis of the nozzle 20 such that the resin orifice 21 communicates with a gate (not designated by any reference numeral), which is integrally formed at the end of the nozzle 20 or is coupled to the end of the nozzle 20 after being produced separately from the nozzle 20. The gate is configured such that it is coupled to an end of a mold, while a heater wire h is wound around the nozzle 20 such that the heater wire heats the resin passing through the resin orifice 21 and prevents the resin from hardening. The nozzle 20 has a valve pin 25 in the resin orifice 21 which is formed through the central axis of the nozzle 20. The valve pin 25 has a diameter smaller than the inner diameter of the resin orifice 21, so that the resin can flow around the valve pin 25 in the resin orifice 21. The valve pin 25 moves upwards and downwards in the resin orifice 21 so as to open and close the gate. During upward movement of the valve pin 25, the upper end of the valve pin 25 passes through the manifold 10 and is coupled to the drive unit 30. In the present invention, the drive unit 30 can move the valve pin 25 upwards or downwards using hydraulic pressure or pneumatic pressure as actuating pressure. The drive unit 30 is well known in the related art and further explanation is thus deemed unnecessary. The nozzle 20 having the above-mentioned construction is installed at a position below the lower surface of the manifold 10, receives the resin from the manifold 10, and injects the resin into the cavity of the mold.

[34] The resin pressure control means variably controls at least either the inner diameter of the branching resin paths 11 of the manifold 10 or the inner diameter of the resin orifices 21 of the nozzles 20, thus controlling the amount of resin that passes through the gates. The resin pressure control means comprises a pressure control pin 40, a support body 50 and a control body 60. The resin pressure control means may be located at a variety of positions in the injection-molding machine of the present invention, as will be described herein below with reference to FIG. 1.

[35] The pressure control pin 40 is a longitudinal member, which has a predetermined length and is placed in the manifold 10 such that the lower end of the pressure control pin 40 is placed the position at which the resin path 11 of the manifold 10 perpendicularly joins the resin orifice 21 of the nozzle 20 in the installation hole of the manifold 10. The upper end of the pressure control pin 40 passes through the upper end of the manifold 10 and projects outside the manifold 10. The manifold 10 is provided with a pin through hole to allow the pressure control pin 40 to pass through the pin

through hole of the manifold 10, with a bushing (not shown) installed in the pin through hole of the manifold 10 to seal the manifold 10. The pressure control pin 40 is placed in the manifold 10 such that the pin 40 can change its vertical position. One end of the pressure control pin 40 is tapered to form a tapered end, which allows the diameter of the resin path 11 to be reduced. Furthermore, the installation hole of the manifold 10, in which the pressure control pin 40 is placed, is configured such that it has a tapered shape corresponding to the tapered end of the pressure control pin 40. The pressure control pin 40 is held by the support body 50 such that the pin 40 is movable in a vertical direction.

[36] The support body 50 is a unit for supporting the outer circumferential surface of the upper end of the pressure control pin 40 so that it is placed on the upper end of the manifold 10, in which the pressure control pin 40 is placed. The support body 50 is coupled to the manifold 10 through fitting or welding. The control body 60 is rotatably placed around the support body 50.

[37] The control body 60 is a unit, which is operated in response to manipulation by a user and moves the pressure control pin 40 upwards or downwards. The control unit 60 rotatably surrounds the support body 50 and engages with the upper end of the pressure control pin 40 through a threaded engagement. The control body 60 is preferably knurled and is provided with a notch-mark around the outer circumferential surface thereof, thus allowing a worker to more efficiently manipulate and use the control body 60 while checking the angle of rotation of the control body 60.

[38] The pressure control pin 40 preferably has a structure to enable assembly with the support body 50 such that the pressure control pin 40 is not rotatable relative to the support body 50 but is vertically movable relative to the support body 50 during rotation of the control body 60. Thus, the pressure control pin 40 can be easily moved vertically. For example, the pressure control pin 40 may be configured as a pin having a polygonal cross-section, while a pin through hole of the support body 50, through which the pressure control pin 40 passes, may be configured as a hole having a polygonal cross-section corresponding to the pin 40. Thus, when the control body 60 is rotated at a predetermined angle in a forward or reverse direction, the pressure control pin 40, which engages with the control body 60 through a threaded engagement, is moved upwards or downwards.

[39] If there occurs a machining error in a resin path 11 of the manifold 10 associated with a nozzle 20 or in the resin orifice 21 of a nozzle 20 of the injection-molding machine having the resin pressure control means, the control body 60 associated with the nozzle 20 is appropriately rotated so that the pressure control pin 40 is moved downwards or upwards to adjust the diameter of the resin path 11. Thus, the pressure of the resin passing through the resin path 11 is controlled, thereby adjusting the

injection amount of the nozzle 20.

[40] FlG. 2 is a view illustrating a valve pin nozzle-type injection-molding machine according to the present invention, in which the lower end of the pressure control pin 40 of the resin pressure control means extends to a position around the resin orifice 21 adjacent to the gate of the nozzle 20, but the general shape of the injection-molding machine except for the pressure control pin 40 remains the same as that described for the embodiment of FlG. 1. That is, the injection-molding machine having resin pressure control means shown in FlG. 2 has a plurality of nozzles 20, which is coupled to the lower end of the manifold 10 having a plurality of branching resin paths 11. The pressure control pin 40 is vertically movably placed in the injection-molding machine such that the lower end of the pin 40 is placed at a position around the resin orifice 21 of the nozzle 20 and the upper end of the pin 40 passes through the upper end of the manifold 10 and projects outside the manifold 10 in the same manner as that described for the embodiment of FlG. 1. The lower end of the pressure control pin 40, which is the end placed around the resin orifice 21 of the nozzle 20, is tapered to form a tapered end, so that the diameter of the resin path 11 can be reduced. The resin orifice 21 of the nozzle 20, at which the tapered lower end of the pressure control pin 40 is placed, is also tapered to correspond to the tapered shape of the lower end of the pressure control pin 40, as illustrated in the drawing.

[41] The pressure control pin 40 is supported by the support body 50 such that the pin

40 is prevented from being rotated but is vertically movable relative to the support body 50. The support body 50 is assembled through fitting or welding with the upper end of the manifold 10, in which the pressure control pin 40 is placed. Furthermore, the control body 60 is rotatably placed around the support body 50. The control body 60 is operated in response to manipulation by a user and moves the pressure control pin 40 upwards or downwards. The control unit 60 rotatably surrounds the support body 50 and engages with the upper end of the pressure control pin 40 through a threaded engagement.

[42] The injection-molding machine having the resin pressure control means shown in

FlG. 2 executes the same operation as that of the embodiment of FlG. 1, thus moving the pressure control pin 40 vertically upwards or downwards and controlling the diameter of the resin orifice 21, so that the injection amount of each nozzle 20 can be adjusted. The injection-molding machine of FlG. 2 makes the injection amounts of the nozzles 20 consistent.

[43] FlG. 3 and FlG. 4 are views illustrating open nozzle-type injection-molding machines using the resin pressure control means according to the first embodiment of the present invention. Each of the injection-molding machines having the resin pressure control means of FIGS. 3 and 4 comprises a manifold 10, a plurality of

nozzles 20, and a resin pressure control means.

[44] First, the construction of the injection-molding machines will be described in detail with reference to FIG. 3 and FIG. 4. As shown in the drawings, the general shape of the injection-molding machines of FIGS. 3 and 4 remains the same as that of the injection-molding machines of FIGS. 1 and 2, but the injection-molding machines of FIGS. 3 and 4 have no valve pin and no drive unit to actuate the valve pin, unlike the injection-molding machines of FIGS. 1 and 2. That is, each of the injection-molding machines having the resin pressure control means shown in FIG. 3 and FIG. 4 comprises a manifold 10, having a plurality of branching resin paths 11 therein, and a plurality of nozzles 20 coupled to the lower end of the manifold 10. The injection- molding machine further includes a pressure control pin 40, which constitutes the resin pressure control means for variably controlling the diameter of each resin path 11 of the manifold 10 or the diameter of the resin orifice 21 of each nozzle 20.

[45] The resin pressure control means of FIG. 3 comprises a pressure control pin 40, a support body 50 and a control body 60. The pressure control pin 40 is a longitudinal member, which has a predetermined length and is placed in the manifold 10 such that the lower end of the pressure control pin 40 is placed the position at which the resin path 11 of the manifold 10 perpendicularly joins the resin orifice 21 of the nozzle 20 in the installation hole of the manifold 10. The upper end of the pressure control pin 40 passes through the upper end of the manifold 10 and projects outside the manifold 10. The manifold 10 is provided with a pin through hole to allow the pressure control pin 40 to pass through the pin through hole of the manifold 10, with a bushing (not shown) installed in the pin through hole of the manifold 10 to seal the manifold 10. The pressure control pin 40 is placed in the manifold 10 such that the pin 40 can change its vertical position. One end of the pressure control pin 40 is tapered to form a tapered end, which allows the diameter of the resin path 11 to be reduced. Furthermore, the installation hole of the manifold 10, in which the pressure control pin 40 is placed, is configured such that it has a tapered shape corresponding to the tapered end of the pressure control pin 40. The pressure control pin 40 is held by the support body 50 such that the pin 40 is prevented from rotating relative to the support body 50 but is movable in a vertical direction.

[46] The support body 50 is placed on the upper end of the manifold 10, in which the pressure control pin 40 is placed, and supports the outer circumferential surface of the upper end of the pressure control pin 40. The support body 50 is coupled to the manifold 10 through fitting or welding. The control body 60 is rotatably placed around the support body 50.

[47] The control body 60 is operated in response to manipulation by a user and moves the pressure control pin 40 upwards or downwards. The control unit 60 rotatably

surrounds the support body 50 and engages with the upper end of the pressure control pin 40 through a threaded engagement. Due to the above-mentioned construction, when the control body 60 is rotated at a predetermined angle in a forward or reverse direction, the pressure control pin 40, which engages with the control body 60 through the threaded engagement, is moved upwards or downwards.

[48] If there occurs a machining error in a resin path 11 of the manifold 10 associated with a nozzle 20 or in the resin orifice 21 of a nozzle 20 of the injection-molding machine having the above-mentioned resin pressure control means, the control body 60 associated with the nozzle 20 is appropriately rotated so that the pressure control pin 40 is moved downwards or upwards to adjust the diameter of the resin path 11. Thus, the pressure of the resin passing through the resin path 11 is controlled, thereby adjusting the injection amount of the nozzle 20.

[49] FlG. 4 is a view illustrating an open nozzle-type injection-molding machine according to the present invention, in which the lower end of the pressure control pin 40 constituting the resin pressure control means extends to a position around the resin orifice 21 adjacent to the gate of the nozzle 20, but the general shape of the injection- molding machine of FlG. 4 except for the pressure control pin 40 remains the same as that described for the embodiment of FlG. 3. Because the construction of the resin pressure control means of FlG. 4 is highly similar to that of the embodiment of FlG. 3, further explanation is thus deemed unnecessary. The injection-molding machine having the resin pressure control means shown in FlG. 4 conducts the same operation as that of the embodiment of FlG. 3, thus moving the pressure control pin 40 vertically upwards or downwards, controlling the diameter of the resin orifice 21, and adjusting the injection amount of the nozzle 20.

[50] FlG. 5 is a sectional view illustrating an embodiment in which the resin pressure control means of the present invention is adapted to a manifold 10. In the embodiment of FlG. 5, the resin pressure control means is provided in the branching resin path 11 of the manifold 10 constituting the injection-molding machine. That is, like the above- mentioned embodiments, the resin pressure control means of FlG. 5 comprises a pressure control pin 40, a support body 50, and a control body 60. The pressure control pin 40 is a longitudinal member, which has a predetermined length and is placed in the manifold 10 such that the lower end of the pressure control pin 40 is placed in a predetermined position in the resin path 11 of the manifold 10. The upper end of the pressure control pin 40 passes through the upper end of the manifold 10 and projects outside the manifold 10. The manifold 10 is provided with a pin through hole to allow the pressure control pin 40 to pass through the pin through hole, with a bushing (not shown) installed in the pin through hole of the manifold 10 to seal the manifold 10. The pressure control pin 40 is placed in the manifold 10 such that the pin 40 can

change its vertical position. One end of the pressure control pin 40 is machined such that it allows the diameter of the resin path 11 to be reduced and minimizes the flow rate of resin.

[51] Furthermore, the pressure control pin 40 is held by the support body 50 such that the pin 40 is prevented from rotating but is movable in a vertical direction.

[52] The support body 50 is placed on the upper end of the manifold 10, in which the pressure control pin 40 is placed, and supports the outer circumferential surface of the upper end of the pressure control pin 40. The support body 50 is coupled to the manifold 10 through fitting or welding. The control body 60 is rotatably placed around the support body 50.

[53] The control body 60 is a unit, which is operated in response to manipulation by a user and moves the pressure control pin 40 upwards or downwards. The control unit 60 rotatably surrounds the support body 50 and engages with the upper end of the pressure control pin 40 through a threaded engagement. Due to the above-mentioned construction, when the control body 60 is rotated at a predetermined angle in a forward or reverse direction, the pressure control pin 40, which engages with the control body 60 through the threaded engagement, is moved upwards or downwards.

[54] If there occurs a machining error in a resin path 11 of the manifold 10 associated with a nozzle 20 or in the resin orifice 21 of a nozzle 20 of the injection-molding machine having the above-mentioned resin pressure control means, the control body 60 associated with the nozzle 20 is appropriately rotated so that the pressure control pin 40 is moved downwards or upwards to adjust the diameter of the resin path 11 of the manifold. Thus, the pressure of the resin passing through the resin path 11 is controlled, thereby equally adjusting the injection amounts of the nozzles 20.

[55] FIG. 6 through FIG. 14 are views illustrating resin pressure control means according to the second embodiment of the present invention. The resin pressure control means according to the second embodiment of the present invention may be adapted to a valve pin nozzle, an open nozzle, or a manifold. FIGS. 6 through 8 are views showing the resin pressure control means according to the second embodiment of the present invention. FIG. 6 is a view illustrating a valve pin nozzle-type injection- molding machine having the resin pressure control means according to the second embodiment of the present invention. FIG. 7 is a perspective view illustrating an important part of the resin pressure control means according to the second embodiment. FIG. 8 is a sectional view taken along line A-A of FIG. 6, and explains the operation of controlling the opening ratio executed by the resin pressure control means.

[56] As shown in the drawings, the general construction of the injection-molding machine according to the second embodiment remains the same as that of the

injection-molding machine according to the first embodiment of FlG. 1 and FlG. 2. However, the resin pressure control means, which is provided in the resin orifice 21 of a resin nozzle 20 or in the resin path 11 of a manifold 10 linearly communicating with the resin orifice 21 so as to variably control the diameter of the resin orifice 21 or the resin path 11 and control the amount of resin passing through the nozzle 20, comprises a flow control rotary pin 70, a support body 80, and a control bar 90, unlike the first embodiment.

[57] The flow control rotary pin 70, which is a longitudinal member having a predetermined length, is rotatably installed in the manifold 10 such that the lower end of the pin 70 is placed in the resin orifice 21 of the nozzle 20 or in the resin path 11 of the manifold 10 linearly communicating with the resin orifice 21. The upper end of the flow control rotary pin 70 extends upwards to project outside the upper end of the manifold 10, with a worm wheel 72 having threads around its outer circumferential surface integrally formed at the upper end of the flow control rotary pin 70 such that the worm wheel 72 engages with the control bar 90 through a worm gear engagement, as will be described later herein. The flow control rotary pin 70 is provided with an integral pipeline 71, which acts as a resin channel to allow resin to pass through the channel. The pipeline 71 is configured as a normal pipeline for connecting the horizontal resin path 11 of the manifold 10 to the vertical resin orifice 21 of the nozzle 20. That is, an inlet of the normal pipeline 71, which communicates with the horizontal resin path 11 of the manifold 10, is formed on a predetermined position of a side surface of the flow control rotary pin 70. An outlet of the normal pipeline 71 is formed to face downwards and communicates with the resin orifice 21 of the nozzle 20. Thus, the pipeline 71 defines the resin channel to feed resin from the manifold 10 to the nozzle 20.

[58] An axial pin through hole (not shown) is formed through the central axis of the flow control rotary pin 70, so that a valve pin 25 movably passes through the pin through hole and moves upwards and downwards. The pin through hole of the flow control rotary pin 70 is connected to one side of the pipeline 71. To cause the pipeline 71 to easily feed resin without interfering with the location of the valve pin 25, the pipeline 71 is configured such that it has an inner diameter larger than the diameter of the valve pin 25. Furthermore, to allow stable rotation of the flow control rotary pin 70 and to prevent leakage of resin toward the manifold 10, both a bushing (not shown) and a seal ring (not shown) are preferably installed around the outer surface of the flow control rotary pin 70, at which the pin 70 is in contact with the manifold 10. Both the bushing and the seal ring are well known to those skilled in the art, and further explanation is thus deemed unnecessary. Because the flow control rotary pin 70 having the above-mentioned construction is rotatably provided in the injection-molding

machine according to the second embodiment, the opening ratio of the inlet of the pipeline 71 can be controlled. Thus, the amount of resin passing through the pipeline 71 can be adjusted. The flow control rotary pin 70 is rotatably supported by the support body 80.

[59] The support body 80 is a casing-shaped member and is securely installed on a predetermined position of the upper end of the manifold 10, in which the upper end of the flow control rotary pin 70 is placed. The support body 80 rotatably supports the outer circumferential surface of the upper end of the flow control rotary pin 70. The support body 80 is coupled to the manifold 10 through welding, a threaded engagement, or fitting.

[60] The control bar 90 is a control member, which actuates the flow control rotary pin

70 in response to manipulation by a user, thus rotating the flow control rotary pin 70 at a predetermined angle of rotation. The control bar 90 is placed such that the control bar 90 horizontally passes through a sidewall of the support body 80 and perpendicularly engages with the flow control rotary pin 70. In the above case, the control bar 90 is rotatable in a forward or reverse direction. Furthermore, the inner end of the control bar 90 is integrally provided with a worm 92, which has threads around its outer circumferential surface, thus engaging with the worm wheel 72 of the upper end of the flow control rotary pin 70 through a worm gear engagement. The outer end of the control bar 90 is preferably knurled and is provided with a notch-mark around the outer circumferential surface thereof, thus allowing a worker to more efficiently manipulate and use the control bar 90 while checking the angle of rotation of the control bar 90. When the control bar 90 is rotated at a predetermined angle in either direction by a worker, the flow control rotary pin 70, which engages with the control bar 90 through the worm gear engagement, is operated in conjunction with the control bar 90, thus being rotated at a predetermined angle in a forward or reverse direction, so that the opening ratio of the pipeline 71 formed in the flow control rotary pin 70 can be adjusted.

[61] If the injection amounts of the respective nozzles of a multi-nozzle-type injection- molding machine having the above-mentioned resin pressure control means are not equal to each other, the control bar 90 associated with a nozzle 20 to be adjusted is rotated in either direction. Thus, the flow control rotary pin 70, which engages with the control bar 90 through the worm gear engagement, is operated in conjunction with the control bar 90, thus being rotated. Accordingly, as shown in FIG. 8, the location of the inlet of the pipeline 71 is changed so that the opening ratio of the inlet of the pipeline

71 is adjusted based on the resin path 11. Due to the adjustment in the opening ratio of the inlet of the pipeline 71, the amount of resin passing through the pipeline 71 can be controlled and the injection amount of the nozzle 20 can be adjusted.

[62] FlG. 9 through FlG. 11 show the resin pressure control means according to the second embodiment, which is adapted to an open nozzle-type injection-molding machine. The general construction of the injection-molding machine of FlG. 9 through FlG. 11 remains the same as that of the injection-molding machine shown in FlG. 6 through FlG. 8. However, when comparing the construction of the injection-molding machine of FIGS. 9 through 11 to that of the injection-molding machine shown in FIGS. 6 through 8, it is noted that the injection-molding machine of FIGS. 9 through 11 has no valve pin and no drive unit to actuate the valve pin, unlike the injection- molding machines of FIGS. 6 through 8. In the following description, those elements common to the embodiments will thus carry the same reference numerals.

[63] As shown in the drawings, this injection-molding machine comprises a manifold 10 having a resin path 11 therein and a plurality of nozzles 20 coupled to the lower end of the manifold 10. The resin pressure control means is provided in the resin orifice 21 of the resin nozzle 20 or in the resin path 11 of the manifold 10, linearly communicating with the resin orifice 21, so as to variably control the diameter of the resin orifice 21 or the resin path 11 and thus control the amount of resin passing through the nozzle 20. Like the embodiment of FIGS. 6 through 8, the resin pressure control means of FIGS. 9 through 11 comprises a flow control rotary pin 70, a support body 80, and a control bar 90.

[64] The flow control rotary pin 70, which is a longitudinal member having a predetermined length, is rotatably installed in the manifold 10 such that the lower end of the flow control rotary pin 70 is placed in the resin orifice 21 of the nozzle 20 or in the resin path 11 of the manifold 10, which linearly communicates with the resin orifice 21. The upper end of the flow control rotary pin 70 extends upwards to project outside the upper end of the manifold 10, with a worm wheel 72 having threads around its outer circumferential surface integrally formed at the upper end of the flow control rotary pin 70 such that the worm wheel 72 engages with the control bar 90 through a worm gear engagement, as will be described later herein. The flow control rotary pin 70 is provided with an integral pipeline 71, which acts as a resin channel to allow resin to pass through the channel. The pipeline 71 is configured as a normal pipeline for connecting the horizontal resin path 11 of the manifold 10 to the vertical resin orifice 21 of the nozzle 20.

[65] Because the flow control rotary pin 70 having the above-mentioned construction is rotatably provided in the injection-molding machine, the opening ratio of the inlet of the pipeline 71 can be controlled. Thus, the amount of resin passing through the pipeline 71 can be adjusted.

[66] The flow control rotary pin 70 is rotatably supported by the casing-shaped support body 80. The support body 80 is securely installed on a predetermined position of the

upper end of the manifold 10, in which the upper end of the flow control rotary pin 70 is placed. The support body 80 rotatably supports the outer circumferential surface of the upper end of the flow control rotary pin 70. Furthermore, the control bar 90 is a bar-shaped control member having a predetermined length, one end of which has a worm 92 to engage with the upper circumferential surface of the flow control rotary pin 70 through a worm gear engagement. The other end of the control bar 90 is preferably knurled and is provided with a notch-mark around the outer circumferential surface thereof, thus allowing a worker to more efficiently manipulate and use the control bar 90 while checking the angle of rotation of the control bar 90. When the control bar 90 is rotated at a predetermined angle in either direction by a worker, the flow control rotary pin 70, which engages with the control bar 90 through the worm gear engagement, is operated in conjunction with the control bar 90, thus being rotated at a predetermined angle in a forward or reverse direction, so that the opening ratio of the pipeline 71 formed in the flow control rotary pin 70 can be adjusted.

[67] When the control bar 90 of the injection-molding machine having the resin pressure control means of FIGS. 9 through 11 is rotated in either direction, the flow control rotary pin 70, which engages with the control bar 90 through the worm gear engagement, is operated in conjunction with the control bar 90, thus being rotated in a forward or reverse direction. Accordingly, as shown in FIG. 11, the location of the inlet of the pipeline 71 is changed so that the opening ratio of the inlet of the pipeline 71 is adjusted based on the resin path 11. Thus, the amount of resin passing through the pipeline 71 can be controlled and the injection amount of the nozzle 20 can be adjusted.

[68] FIG. 12 through FIG. 14 are views illustrating the resin pressure control means according to the second embodiment of the present invention, which is adapted to a manifold 10. FIG. 12 is a sectional view illustrating an injection-molding machine having a manifold using the resin pressure control means according to the second embodiment. FIG. 13 is a perspective view illustrating an important part of the resin pressure control means used in the injection-molding machine of FIG. 12. FIG. 14 is a sectional view taken along line C-C of FIG. 12, which explains the operation of controlling the resin injection amount.

[69] The general construction of the resin pressure control means, which is provided in the resin path 11 of the manifold 10 shown in FIG. 12 through FIG. 14, remains the same as that of the resin pressure control means shown in FIG. 6 through FIG. 11, so that, in the following description, those elements common to the embodiments will thus carry the same reference numerals.

[70] That is, this resin pressure control means comprises a flow control rotary pin 70, a support body 80, and a control bar 90. The flow control rotary pin 70 is a longitudinal

member, which has a predetermined length and is rotatably installed in the manifold 10 such that one end of the flow control rotary pin 70 can close the horizontal resin path 11 of the manifold 10. A pipeline 71, which acts as a resin channel, is formed in the manifold 10 such that the pipeline 71 is aligned with the horizontal resin path 11 of the manifold 10. The other end of the flow control rotary pin 70 extends upwards such that it projects outside the upper end of the manifold 10. The upper end of the flow control rotary pin 70 is integrally provided with a worm wheel 72, which has threads around the outer circumferential surface thereof and engages with the control bar 90 through a worm gear engagement, as will be described later herein. The lower end of the flow control rotary pin 70, which is placed in the horizontal resin path 11, preferably has a spherical shape such that the spherical lower end of the pin 70 can efficiently cooperate with the tubular resin path 11, which typically has a circular cross-section.

[71] Because the flow control rotary pin 70 is rotatably installed as described above, the opening ratio of the inlet of the pipeline 71 can be variably controlled. Thus, the amount of resin passing through the pipeline 71 can be adjusted. The flow control rotary pin 70 is rotatably supported by the support body 80 and is rotated by rotation of the control bar 90, which engages with the flow control rotary pin 70 through a worm gear engagement and is manipulated by a user. The construction and operation of both the support body 80 and the control bar 90 remain the same as those described for the embodiments of FlG. 6 through FlG. 11, and further explanation is thus deemed unnecessary.

[72] When the control bar 90 of the injection-molding machine having the resin pressure control means of FIGS. 12 through 14 is rotated in either direction, the flow control rotary pin 70, which engages with the worm 92 of the control bar 90 through the worm gear engagement, is operated in conjunction with the control bar 90, thus being rotated in a forward or reverse direction, so that the inlet of the pipeline 71 is misaligned with the resin path 11. Accordingly, as shown in FlG. 14, the location of the inlet of the pipeline 71 is changed, thus adjusting the opening ratio of the inlet of the pipeline 71 based on the resin path 11. Therefore, the amount of resin passing through the pipeline 71 can be controlled and the injection amount of the nozzle 20 can be adjusted. Industrial Applicability

[73] As apparent from the above description for the construction and operation, the injection-molding machine having the resin pressure control means according to the present invention is configured such that a worker can precisely control the amounts of resin to be injected from respective nozzles through a simple manipulation by a user, thus compensating for nonuniform injection amounts caused by machining errors of

the nozzles in an injection-molding machine having multiple nozzles or by machining errors of resin paths branching from a manifold, thereby remarkably improving the quality of the molded products.

[74] Although preferred embodiments of the present invention have been described 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 claim.