Injection molding device

Abstract

The present invention provides an injection molding device that enables injection molding to be performed without creating a gap between a nozzle touch block and a manifold. The injection molding device according to the present invention comprises: an injecting unit; a fixed mold 1; a movable mold 2 that forms a cavity 3 between the opposing surfaces of the fixed mold 1 and the movable mold 2; a manifold 4 that is disposed on the fixed mold 1 and that is provided with a plurality of hot runners 5, 6; a guide member 9 that is disposed on the manifold 4; a nozzle touch block 10 that is disposed with freedom to move along the guide member 9; and lock pins R1 that are removably inserted into lock holes 10d, 10e formed in the nozzle touch block 10 and that fix the nozzle touch block 10 on the movement path thereof in a state in which introduction openings of introduction paths have been positioned with respect to the hot runners 5, 6.

Description

injection molding equipment

[0001] The present invention relates to an injection molding apparatus capable of injection molding molded products of different colors.

[0002] As an injection molding apparatus capable of changing the color of a molded product using a single mold, there has been known a conventional injection molding apparatus, as described in Patent Document 1, which includes a manifold configured to provide a hot runner block, which is the main body of the manifold, with multiple independent hot runners that each circulate molten resin of a different color, and to supply the molten resin into a cavity through these hot runners, and a nozzle touch block that is supported on the manifold so that the upper surfaces of both ends of the nozzle touch block are slidably supported by a pair of parallel guide members, and that has multiple resin inlet ports drilled at predetermined intervals to correspond to the multiple hot runners, respectively.

[0003] The nozzle touch block is then moved until a desired one of the multiple resin inlet ports drilled in the nozzle touch block reaches directly below the nozzle of the injection unit, and is stopped at that position, thereby connecting the resin injection hole to the inlet of a hot runner that is provided in correspondence with the resin inlet of one of the multiple hot runners provided in the manifold.

[0004] Therefore, for example, if a hot runner that circulates white-colored molten resin and a hot runner that circulates black-colored molten resin are provided in the manifold, and the nozzle touch block is provided with an inlet for white-colored molten resin and an inlet for black-colored molten resin that communicate with the inlets of these hot runners, respectively, the nozzle touch block can be moved until the white-colored molten resin inlet of the nozzle touch block reaches directly below the nozzle of the injection unit and stopped in that position, and the white-colored molten resin can be injected from the nozzle of the injection unit into the inlet, and the molten resin can be filled into the cavity through the hot runner that circulates the white molten resin, thereby producing a white molded product.

[0005] In addition, by moving the nozzle touch block so that the black-colored molten resin inlet is positioned directly below the nozzle of the injection unit, and then injecting the black-colored molten resin from the nozzle of the injection unit into the black molten resin inlet, the molten resin can be filled into the cavity through a hot runner that is connected to this inlet and circulates the black molten resin, thereby producing a black molded product.

[0006] JP 2014-12380 A

[0007] However, in an injection molding die configured as described above that allows color changes, a gap occurs between the opposing surfaces of the manifold and the nozzle touch block that slides on the manifold, and there is a risk that the molten resin injected from the nozzle of the injection unit into the inlet of the nozzle touch block will leak through this gap.

[0008] For this reason, the injection molding apparatus is provided with a pressing means that forcibly presses the nozzle touch block, which slides on the manifold, against the manifold. This pressing means has extremely low protrusions provided at regular intervals in the direction of movement of the nozzle touch block on the upper surface of both side ends of the nozzle touch block and on the lower surface of the guide member that supports the nozzle touch block so that it can slide and presses against these upper surface of both side ends. When the nozzle touch block is moved along the guide member and one of its introduction ports is positioned directly below the nozzle of the injection unit, the protrusions on the upper surface of both side ends of the nozzle touch block ride up onto the protrusions on the lower surface of the guide member, thereby pressing the nozzle touch block against the manifold and preventing any gaps from forming.

[0009] With a pressing means configured in this manner, during injection molding, when molten resin extruded from the nozzle of the injection unit flows from the inlet of the nozzle touch block through the hot runner in the manifold and into the cavity, the nozzle touch block can be forcibly pressed onto the manifold by the overlapping of the protrusions protruding from the underside of the guide member and the upper surfaces of both end portions of the nozzle touch block. However, in order to overlap the protrusions, the nozzle touch block must be moved horizontally along the manifold so that one protrusion rides up on the other, and in this process, resistance is generated due to the collision between the protrusions, which may interfere with the smooth operation of the nozzle touch block and make it more susceptible to malfunction. Furthermore, there is a risk that the inlet of the nozzle touch block cannot be accurately aligned with the inlet of the hot runner provided in the manifold.

[0010] Furthermore, repeated polymerization of the protrusions causes the protrusions to wear down, and gaps are more likely to form between the manifold and the nozzle touch block, not only when the protrusions are not overlapping, but also when they are overlapping, resulting in problems such as the inability to prevent leakage of molten resin.

[0011] The present invention provides an injection molding apparatus that allows the nozzle touch block to always slide smoothly and accurately in contact with the flat surface of the manifold, and that accurately aligns the inlet of the introduction path in the nozzle touch block with the inlet of the hot runner, allowing injection molding to be performed without creating a gap between the nozzle touch block and the manifold.

[0012] an injection molding apparatus according to the present invention, comprising: an injection unit having a nozzle for supplying molten resin; a fixed mold; a movable mold which forms a cavity between opposing surfaces of the fixed mold; a manifold which is disposed on the fixed mold and has a plurality of independent hot runners therein through which molten resins of different colors respectively flow; a guide member which is disposed on the manifold; a nozzle touch block which is disposed movably along the guide member and has a plurality of introduction paths corresponding to each of the plurality of hot runners, the introduction paths communicating with the corresponding hot runners when the nozzle touch block is moved along the guide member to face directly below the nozzle of the injection unit during injection molding; and a lock pin which is removably inserted into a lock hole formed in the nozzle touch block with any introduction path of the nozzle touch block communicating with the hot runner corresponding to the introduction path, and which fixes the nozzle touch block on its movement path with the introduction port of the introduction path positioned relative to the hot runner.

[0013] In the injection molding apparatus of the present invention, with the inlet of the introduction passage of the nozzle touch block positioned at the inlet of the hot runner, the lock pin can be inserted into the lock hole of the nozzle touch block to fix the nozzle touch block at a predetermined position on the manifold. Therefore, the introduction port of the introduction passage located directly below the injection unit can be accurately positioned at the inlet of the hot runner corresponding to this introduction passage, and injection molding can be performed without causing resin leakage.

[0014] In the above-mentioned injection molding apparatus, when the nozzle touch block has the lock hole formed in each of its portions facing the lock pin with each of the multiple introduction paths facing directly below the nozzle of the injection unit, the following effect is achieved: The injection unit and lock pin can be disposed and fixed in a predetermined position, and only the nozzle touch block can be moved along the guide member, and the nozzle touch block can be moved and fixed in an accurate position with the lock pin, accurately connecting the introduction port of the introduction path of the nozzle touch block with the inlet of the hot runner and preventing resin leakage from the connection.

[0015] In the above-mentioned injection molding apparatus, if an enlarged diameter portion having a circular cross section is formed in the lock hole of the nozzle touch block and a reduced diameter portion having a circular cross section is formed at the tip of the lock pin, and when the lock pin is inserted into the lock hole, the peripheral surface of the reduced diameter portion on the guide member side is brought into sliding contact with the inner peripheral surface of the lock hole of the nozzle touch block, the following effects are achieved.

[0016] The open end of the lock hole gradually expands in diameter, while the tip of the lock pin is formed with a gradually decreasing diameter. Therefore, even if the axis of the lock pin and the center of the lock hole are slightly misaligned, the lock pin can be inserted into the lock hole. When the tip of the lock pin is inserted into the lock hole, the tip presses against the inner surface of the lock hole as needed, accurately moving the nozzle touch block to the specified position and fixing it in place on the manifold.

[0017] In the injection molding apparatus, when the lock pin is misaligned toward the manifold with respect to the lock hole of the nozzle touch block, the following effect is achieved. That is, by inserting the lock pin into the lock hole of the nozzle touch block, the lock pin inserted into the lock hole of the nozzle touch block presses against the inner circumferential surface of the lock hole, pressing the nozzle touch block toward the manifold. Therefore, the inlet of the introduction passage of the nozzle touch block can be crimped while being accurately connected to the inlet of the hot runner, preventing resin leakage.

[0018] In the above-mentioned injection molding apparatus, when the nozzle touch block has an opening path for opening to the outside those hot runners among the multiple hot runners of the manifold that are not connected to the introduction path of the nozzle touch block, the following effects are obtained.

[0019] When injection molding is performed using one of the multiple hot runners on a manifold and then the hot runner is switched to another hot runner, the hot runner used before the switch is filled with molten resin under pressure. After switching to the other hot runner, the inlet of the previous hot runner is closed by the nozzle touch block. As a result, the molten resin under pressure that fills the hot runner applies stress that pushes up on the nozzle touch block. By providing an opening path in the nozzle touch block to expose unused hot runners that are not connected to the nozzle touch block's inlet path to the outside, the molten resin filled in the hot runner can be discharged to the outside, eliminating the upward stress on the nozzle touch block caused by the molten resin. This makes it easier to maintain the nozzle touch block in close contact with the manifold, and more effectively prevents leakage of molten resin.

[0020]

[0023] Fig. 2(a) is a simplified longitudinal sectional front view of an injection molding apparatus of the present invention. Fig. 2(a) is a cross-sectional view showing a state in which a first sprue bush of a nozzle touch block is positioned directly below a nozzle of an injection unit, and Fig. 2(b) is a cross-sectional view showing a state in which a second sprue bush of the nozzle touch block is positioned directly below a nozzle of an injection unit. Fig. 2(b) is a perspective view of a nozzle touch block. Fig. 2(b) is a perspective view showing a state in which a first inlet path and a first open path of the nozzle touch block are connected to a first hot runner and a second hot runner. Fig. 2(b) is a cross-sectional view showing a state in which a second inlet path and a second open path of the nozzle touch block are connected to a first hot runner and a second hot runner. Fig. 2(b) is a cross-sectional view of a nozzle touch block and a second drive device. Fig. 7(a) is a schematic view showing a state in which a lock pin is inserted into a first lock hole of the nozzle touch block, and Fig. 7(b) is a schematic view showing a state in which a lock pin is inserted into a second lock hole of the nozzle touch block. Figure 8(a) is a schematic diagram showing the connection state between the first inlet path and first open path of the nozzle touch block and the first hot runner and the second hot runner, and Figure 8(b) is a schematic diagram showing the connection state between the second inlet path and second open path of the nozzle touch block and the first hot runner and the second hot runner.

[0021] An example of an injection molding apparatus according to the present invention will be described with reference to the drawings. The injection molding apparatus shown in the drawings is an example, and the shapes and arrangement of the manifold, guide member, nozzle touch block, and lock pin are not limited to those shown in the drawings.

[0022] In the following, the "first hot runner 5 and second hot runner 6" may be referred to as the "first and second hot runners 5, 6." The "inlet 5a of the first hot runner 5 and the inlet 6a of the second hot runner 6" may be referred to as the "inlet 5a, 6a of the first and second hot runners 5, 6." The "inlet 6a of the second hot runner 6 and the inlet 5a of the first hot runner 5" may be referred to as the "inlet 6a, 5a of the second and first hot runners 6, 5." The "first resin passage 22 and second resin passage 23" may be referred to as the "first and second resin passages 22, 23." The "first gate 22a and second gate 23a" may be referred to as the "first and second gates 22a, 23a." The "first valve pin 25 and second valve pin 26" may be referred to as the "first and second valve pins 25, 26." The "third drive unit 27 and the fourth drive unit 28" may be referred to as the "third and fourth drive units 27 and 28." The "side portion 10b and the side portion 10b" may be referred to as the "side portion 10b and 10b." The "guide member 9 and the guide member 9" may be referred to as the "guide members 9 and 9." The "first inlet 13a of the first inlet passage 13 and the second inlet 14a of the second inlet passage 14" may be referred to as the "first and second inlet ports 13a and 14a of the first and second inlet passages 13 and 14." The "first open port 15a of the first open passage 15 and the second open port 16a of the second open passage 16" may be referred to as the "first and second open ports 15a and 16a of the first and second open passages 15 and 16." The "first sprue bushing 11 and the second sprue bushing 12" may be referred to as the "first and second sprue bushings 11 and 12."

[0023] In FIG. 1, the injection molding device is configured such that a fixed mold 1 and a movable mold 2 are arranged facing each other above and below, and a cavity 3 for obtaining a molded product is formed between the opposing surfaces of these molds 1 and 2, and a manifold 4 is arranged and fixed on the upper surface of the fixed mold 1.

[0024] Inside the manifold 4, two hot runners, a first hot runner 5 and a second hot runner 6, are provided, independent of each other and parallel to each other in the horizontal direction, with a fixed spacing in the vertical direction and the front-to-rear direction (the width direction of the manifold 4). The top surface of the manifold 4 is formed into a smooth, flat surface across its entire surface.

[0025] The manifold 4 has a rectangular parallelepiped base member B disposed in the center in the longitudinal direction of the manifold 4. The base member B has a block shape (rectangular parallelepiped) with a length roughly equal to the width of the manifold 4 and a constant thickness. In the base member B, a surface (first surface) B1 on which a nozzle touch block (described later) is placed is formed as a flat surface. Note that the base member B is not necessarily provided.

[0026] 1 and 2, the inlets 5a, 6a of the first and second hot runners 5, 6 provided within the manifold 4 are formed by holes that penetrate the manifold 4 and the base member B provided on the manifold 4. The inlets 5a, 6a of the first and second hot runners 5, 6 are spaced apart in the width direction of the base member B (the length direction of the manifold 4), with their upper openings facing upward on the first surface B1 of the base member B. The lower ends of the inlets 5a, 6a of the first and second hot runners 5, 6 penetrate the base member B and the manifold 4 to connect and communicate with appropriate locations on the first and second hot runners 5, 6, respectively.

[0027] Both ends of the first and second hot runners 5, 6 inside the manifold 4 are bent downward and open to the bottom surface of the manifold 4. A plurality of valve bodies 21, 21 are mounted in the fixed mold 1 to correspond to the openings at both ends of the first and second hot runners 5, 6. In Figure 1, the valve body 21 is connected to the manifold 4 by pressing the upper end surface of the valve body 21 against the bottom surface of the manifold 4, but the valve body 21 may also be connected to the manifold 4 by forming a threaded portion at the upper end of the valve body 21 and threading this threaded portion into a threaded hole formed in the bottom surface of the manifold.

[0028] First and second resin passages 22, 23, each having a constant diameter, are arranged vertically and parallel to each other within the valve body 21. The upper ends of the first and second resin passages 22, 23 are connected to the openings at both ends of the first and second hot runners 5, 6, respectively. First and second gates 22a, 23a, which communicate with the cavity 3, are provided at the lower ends of the first and second resin passages 22, 23, respectively. The lower ends of the first and second gates 22a, 23a may also communicate directly with the cavity 3. As shown in FIG. 1, the lower ends of the first and second gates 22a, 23a may also communicate with a common passage 24, which in turn communicates with the cavity 3. The valve body 21 is configured to be heated by a heat band (not shown). The lower ends of the first and second gates 22 a and 23 a may be connected to the cavity 3 without the common passage 24 .

[0029] First and second valve pins 25, 26, whose lower ends open and close the first and second gates 22a, 23a, respectively, are inserted into the first and second resin passages 22, 23 so as to be movable back and forth in the vertical direction. The upper ends of the first and second valve pins 25, 26 extend vertically through the manifold 4. The upper ends of the first and second valve pins 25, 26 protrude from the top surface of the manifold 4, and the protruding tips are connected to rods of third and fourth drive devices 27, 28, respectively, which are installed in parallel on the manifold 4. Operation of the third and fourth drive devices 27, 28 moves the first and second valve pins 25, 26 up and down, respectively, so that the lower ends of the first and second valve pins 25, 26 open and close the first and second gates 22a, 23a.

[0030] In the above description, the first and second resin passages are formed in one valve body 21. However, two valve bodies each having one resin passage formed therein may be prepared and mounted in the fixed mold 1 so that they correspond to the openings at both ends of the first and second hot runners 5 and 6, respectively.

[0031] On the base member B, guide members 9, 9 each having an L-shaped cross section are disposed along both widthwise edges thereof. The guide members 9, 9 are disposed parallel to each other at a fixed interval in the widthwise direction of the base member B. The lower ends of the first guide portions of the guide members 9, 9 are fixedly attached to the first surface of the base member B. Side portions 10b, 10b of the nozzle touch block 10, each having a fixed thickness, are fitted into a space surrounded by the smooth inner surfaces of the first and second guide portions of the guide members 9, 9 so as to be movable in the longitudinal direction of the guide members 9, 9. The nozzle touch block 10 has a first surface 10c that faces the first surface B1 of the base member B and is formed as a smooth surface. The nozzle touch block 10 is configured to be able to reciprocate in the length direction (front-rear direction) of the guide members 9,9 while the first surface 10c is in sliding contact with the smooth first surface B1 of the base member B.

[0032] The nozzle touch block 10 has a flat, rectangular base plate 10a of a constant thickness and side portions 10b, 10b formed on both ends of the base plate 10a. As described above, the nozzle touch block 10 is supported movably with the side portions 10b, 10b in sliding contact with the guide members 9, 9. A first sprue bushing 11 and a second sprue bushing 12 are integrally provided in the center of the width direction on the surface 10f of the nozzle touch block 10 (the surface opposite the first surface 10c). The first sprue bushing 11 and the second sprue bushing 12 are disposed at a constant interval along the length of the nozzle touch block 10, i.e., in the direction of movement.

[0033] As shown in FIGS. 2( a) and 3, a first introduction passage 13 is formed within the nozzle touch block 10. The upper end opening of the first introduction passage 13 is open to the center of the tip surface of the first sprue bushing 11. The first introduction passage 13 is inclined in a first direction in the width direction of the nozzle touch block 10 from the upper end opening toward the base member B. The lower end opening of the first introduction passage 13 opens to the first surface 10c of the nozzle touch block 10, forming a first introduction port 13a. When the nozzle touch block 10 is moved and stopped so that the first sprue bushing 11 is directly below the nozzle 20 of the injection unit, the first introduction port 13a of the first introduction passage 13 communicates with the inlet 5a of the first hot runner 5 provided within the manifold 4. The first introduction port 13a is formed to have the same diameter as the inlet 5a of the first hot runner 5.

[0034] Similarly, a second inlet passage 14 is formed within the nozzle touch block 10. The upper end opening of the second inlet passage 14 is open to the center of the tip surface of the second sprue bushing 12. The second inlet passage 14 is inclined from the upper end opening toward the base member B in a second direction (opposite to the first direction) in the width direction of the nozzle touch block 10. The lower end opening of the second inlet passage 14 opens to the first surface 10c of the nozzle touch block 10, forming a second inlet 14a. When the nozzle touch block 10 is moved and stopped so that the second sprue bushing 12 is directly below the nozzle 20 of the injection unit, the second inlet 14a of the second inlet passage 14 communicates with the inlet 6a of the second hot runner 6 provided within the manifold 4. The second inlet 14a is formed to have the same diameter as the inlet 6a of the second hot runner 6.

[0035] A first open passage 15 is formed within the nozzle touch block 10. The first open passage 15 has its upper end opening on the surface of the nozzle touch block 10 excluding the first surface 10c, and is open to the outside air. In FIGS. 3 to 5, the first open passage 15 is shown opening to the side surface of the nozzle touch block 10, but this is not limitative. The first open passage 15 is formed toward the base member B. The lower end opening of the first open passage 15 opens to the first surface 10c of the nozzle touch block 10, forming a first open port 15a. As shown in FIG. 2(a), when the nozzle touch block 10 is moved and stopped so that the first sprue bushing 11 is directly below the nozzle 20 of the injection unit, the first open port 15a of the first open passage 15 communicates with the inlet 6a of the second hot runner 6 provided within the manifold 4. The first open port 15 a is formed to have the same diameter as the upper end opening of the inlet 6 a of the second hot runner 6 .

[0036] Similarly, a second open passage 16 is formed within the nozzle touch block 10. The upper end opening of the second open passage 16 is open to the outside air on all sides of the nozzle touch block 10 except the first surface 10c. In FIGS. 3 to 5, the second open passage 16 is shown opening to the side of the nozzle touch block 10, but this is not limiting. The second open passage 16 is formed toward the base member B. The lower end opening of the second open passage 16 is open to the first surface 10c of the nozzle touch block 10, forming a second open port 16a. As shown in FIG. 2(b), when the nozzle touch block 10 is moved and stopped so that the second sprue bushing 12 is directly below the nozzle 20 of the injection unit, the second open port 16a of the second open passage 16 communicates with the inlet 5a of the first hot runner 5 provided within the manifold 4. The second open port 16 a is formed to have the same diameter as the upper end opening of the inlet 5 a of the first hot runner 6 .

[0037] That is, on the first surface 10c of the nozzle touch block 10, the first inlet 13a of the first inlet passage 13 and the first open opening 15a of the first open passage 15 are formed at the same interval in the width direction of the nozzle touch block 10 (a direction perpendicular to the movement direction of the nozzle touch block 10) as the interval between the upper end openings of the inlet 6a of the first hot runner 6 and the upper end openings of the inlet 6a of the second hot runner 6.

[0038] On the first surface 10c of the nozzle touch block 10, the second inlet 14a of the second inlet passage 14 and the second open opening 16a of the second open passage 16 are formed in the width direction of the nozzle touch block 10 (a direction perpendicular to the movement direction of the nozzle touch block 10) at the same interval as the interval between the upper end openings of the inlet 6a of the first hot runner 6 and the upper end openings of the inlet 6a of the second hot runner 6.

[0039] Furthermore, the first inlet 13a of the first inlet path 13 and the second open port 16a of the second open path 16 are formed on the same straight line in the movement direction of the nozzle touch block 10. Similarly, the second inlet 14a of the second inlet path 14 and the first open port 15a of the first open path 15 are formed on the same straight line in the movement direction of the nozzle touch block 10.

[0040] In the direction of movement of the nozzle touch block 10, the distance between the first inlet 13a of the first inlet passage 13 and the second open port 16a of the second open passage 16 matches the distance between the first sprue bushing 11 and the second sprue bushing 12.

[0041] Similarly, in the direction of movement of the nozzle touch block 10, the distance between the second inlet port 14a of the second inlet passage 14 and the first open port 15a of the first open passage 15 matches the distance between the first sprue bushing 11 and the second sprue bushing 12.

[0042] Therefore, when the nozzle touch block 10 is moved and stopped so that the first sprue bushing 11 is directly below the nozzle 20 of the injection unit, the first inlet 13a of the first inlet passage 13 is connected to the upper opening of the inlet 5a of the first hot runner 5, and the first open port 15a of the first open passage 15 is connected to the upper opening of the inlet 6a of the second hot runner 6, thereby establishing a state of communication (FIGS. 2(a) and 4).

[0043] On the other hand, when the nozzle touch block 10 is moved and stopped so that the second sprue bushing 12 is directly below the nozzle 20 of the injection unit, the second inlet 14a of the second inlet passage 14 is connected to the upper opening of the inlet 6a of the second hot runner 6, and the second open port 16a of the second open passage 16 is connected to the upper opening of the inlet 5a of the first hot runner 5, thereby establishing a state of communication (FIGS. 2(b) and 5).

[0044] A first drive unit (not shown) is connected to the nozzle touch block 10. The first drive unit has an extendable piston rod 19. The piston rod 19 of the first drive unit is connected to the center of the longitudinal end of the nozzle touch block 10. The nozzle touch block 10 is configured to reciprocate back and forth along the guide members 9, 9 as the piston rod 19 extends and retracts. Note that, although not shown, a position detection sensor is provided that detects the positions of the nozzle touch block 10 when the first sprue bushing 11 and the second sprue bushing 12 reach directly below the nozzle 20 of the injection unit and stops operation of the first drive unit as the nozzle touch block 10 moves back and forth in the longitudinal direction by operation of the first drive unit, and when the first sprue bushing 11 and the second sprue bushing 12 reach directly below the nozzle 20 of the injection unit.

[0045] 6, a second drive device R equipped with a lock pin R1 is disposed on the side of the nozzle touch block 10. The lock pin R1 of the second drive device R is configured to be able to advance toward the nozzle touch block 10 or retract in a direction away from the nozzle touch block 10.

[0046] Meanwhile, the nozzle touch block 10 is moved along the guide members 9, 9. When the nozzle touch block 10 has its first sprue bushing 11 positioned directly below the nozzle 20 of the injection unit, a first lock hole 10d is formed in the surface facing the lock pin R1 of the second drive device R, into which the lock pin R1 can be removably inserted (FIG. 7(a)). Similarly, when the nozzle touch block 10 has its second sprue bushing 12 positioned directly below the nozzle 20 of the injection unit, a second lock hole 10e is formed in the surface facing the lock pin R1 of the second drive device R, into which the lock pin R1 can be removably inserted (FIG. 7(b)).

[0047] The nozzle touch block 10 is positioned so that its first sprue bushing 11 or second sprue bushing 12 is directly below the nozzle 20 of the injection unit, and the second drive device R is driven to advance the lock pin R1 toward the nozzle touch block 10. Then, the lock pin R1 is inserted into the first lock hole 10d or the second lock hole 10e that faces the lock pin R1, and the nozzle touch block 10 is fixed at a predetermined position on the movement path.

[0048] Furthermore, the first lock hole 10d and the second lock hole 10e of the nozzle touch block 10 have the same shape. In the first lock hole 10d and the second lock hole 10e of the nozzle touch block 10, the cross section along a plane perpendicular to the movement direction of the lock pin R1 is formed to be circular. The first lock hole 10d and the second lock hole 10e have inner circumferential surfaces formed with expanding diameter portions 10d1, 10e1 that gradually expand in diameter from the inner bottom surface toward the open end. The first lock hole 10d and the second lock hole 10e are formed to be truncated cones.

[0049] On the other hand, the lock pin R1 of the second drive device R has a tip formed with a reduced diameter portion R11 that matches the shape of the first lock hole 10d and the second lock hole 10e. Specifically, the cross section of the tip of the lock pin R1 along a plane perpendicular to the movement direction of the lock pin R1 is circular. The tip of the lock pin R1 is formed with a reduced diameter portion R11 that gradually reduces in diameter toward the tip. The tip of the lock pin R1 is formed with a truncated cone shape. When the lock pin R1 is inserted into the first lock hole 10d or the second lock hole 10e, the reduced diameter portion R11 of the lock pin R1 abuts against the expanded diameter portion 10d1 or 10e1 of the first lock hole 10d or the second lock hole 10e over its entire circumference (entire surface), and the nozzle touch block 10 is configured to be immovably fixed by the lock pin R1.

[0050] The tip of the lock pin R1 is formed as a reduced diameter portion R11, while the inner circumferential surfaces of the first lock hole 10d and the second lock hole 10e are formed as expanded diameter portions 10d1 and 10e1, respectively. Therefore, even if the axis R12 of the lock pin R1 is slightly offset from the center C of the first lock hole 10d and the second lock hole 10e, the lock pin R1 can be inserted into the open ends of the first lock hole 10d and the second lock hole 10e.

[0051] The lock pin R1 of the second drive unit R is disposed so that it is slightly offset toward the manifold 4 with respect to the first lock hole 10d and the second lock hole 10e of the nozzle touch block 10, within a range in which the lock pin R1 can be inserted into the first lock hole 10d and the second lock hole 10e. More specifically, the lock pin R1 of the second drive unit R is disposed so that its axis R12 is slightly offset toward the manifold 4 with respect to the center C of the first lock hole 10d and the second lock hole 10e of the nozzle touch block 10, within a range in which the lock pin R1 can be inserted into the first lock hole 10d and the second lock hole 10e. When the lock pin R1 is inserted into the first lock hole 10d or the second lock hole 10e, the reduced diameter portion R11 of the lock pin R1 presses the expanded diameter portion 10d1, 10e1 of the first lock hole 10d or the second lock hole 10e toward the base member B (manifold 4). As a result, the nozzle touch block 10 is pressed toward the base member B, improving the adhesion between the first and second inlet ports 13a, 14a of the first and second inlet passages 13, 14 and the upper openings of the inlets 5a, 6a of the first and second hot runners 5, 6, and between the first and second open ports 15a, 16a of the first and second open passages 15, 16 and the upper openings of the inlets 6a, 5a of the first and second hot runners 6, 5, and preventing resin leakage from the gap between the nozzle touch block 10 and the base member B of the manifold 4.

[0052] The cross section of the tip of the lock pin R1 taken along a plane perpendicular to the movement direction of the lock pin R1 is not limited to a circular cross section, but may be of other shapes such as a polygonal cross section. In the first lock hole 10d and the second lock hole 10e of the nozzle touch block 10, the cross section of the first lock hole 10d taken along a plane perpendicular to the movement direction of the lock pin R1 is not limited to a circular cross section, but may be of other shapes such as a polygonal cross section.

[0053] As will be described later, the nozzle touch block 10 is controlled so that the first sprue bushing 11 or the second sprue bushing 12 stops at a predetermined position directly below the nozzle 20 of the injection unit. However, the nozzle touch block 10 may stop slightly off-center during the reciprocating motion that occurs each time the color of the injection-molded product is changed. If this misalignment of the nozzle touch block 10 is sufficient to allow the lock pin R1 to be inserted into the first lock hole 10d or the second lock hole 10e, when the lock pin R1 is inserted into the first lock hole 10d or the second lock hole 10e, the reduced-diameter portion R11 of the lock pin R1 presses the enlarged-diameter portions 10d1, 10e1 of the first lock hole 10d or the second lock hole 10e in the movement direction of the nozzle touch block 10 (the guide direction of the guide members 9, 9, the left-right direction in FIGS. 7A and 7B). As a result, the nozzle touch block 10 moves, and the center C of the first lock hole 10d or the second lock hole 10e coincides with the axis R12 of the lock pin R1 in the direction of movement of the nozzle touch block 10 (left and right direction in FIGS. 7A and 7B), correcting the nozzle touch block 10 to a correct position. Therefore, the first and second inlet ports 13a, 14a of the first and second inlet passages 13, 14 and the second and first open ports 16a, 15a of the second and first open passages 16, 15 are connected at accurate positions to the upper end openings of the inlets 5a, 6a of the first and second hot runners 5, 6, respectively, preventing resin leakage from the gap between the nozzle touch block 10 and the base member B of the manifold 4.

[0054] To mold molded products of different colors, for example, a white molded product and a black molded product, using an injection molding apparatus configured in this manner, either one of the first or second sprue bushings 11, 12 provided on the nozzle touch block 10 is set, for example, the first sprue bushing 11 side is set for black molded products and the second sprue bushing 12 side is set for white molded products.

[0055] When molding a black molded product, the first drive unit is operated to move the nozzle touch block 10 along the guide members 9 on both sides (left and right directions in Figures 7(a) and 7(b)). When the first sprue bushing 11 protruding from its upper surface is positioned directly below the nozzle 20 of the injection unit, the position is detected by the position detection sensor and the operation of the first drive unit is stopped.

[0056] Next, the second drive device R is driven to extend (advance) the lock pin R1, inserting the lock pin R1 into the first lock hole 10d of the nozzle touch block 10 and fixing the nozzle touch block 10 at a predetermined position on the movement path. In this state, the first inlet 13a of the first inlet passage 13 of the nozzle touch block 10 is in communication with the upper opening of the inlet 5a of the first hot runner 5, and the first open port 15a of the first open passage 15 of the nozzle touch block 10 is in communication with the upper opening of the inlet 6a of the second hot runner 6 (see FIGS. 2(a), 4, 7(a), and 8(a)).

[0057] At this time, the reduced diameter portion R11 of the lock pin R1 presses the expanded diameter portion 10d1 of the first lock hole 10d toward the base member B, and the nozzle touch block 10 is pressed toward the base member B. This improves the adhesion between the first inlet 13a of the first inlet passage 13 and the upper opening of the inlet 5a of the first hot runner 5, and between the first open port 15a of the first open passage 15 and the upper opening of the inlet 6a of the second hot runner 6, preventing resin leakage from the gap between the nozzle touch block 10 and the base member B of the manifold 4.

[0058] Furthermore, if the nozzle touch block 10 is not positioned accurately in the predetermined stop position, inserting the lock pin R1 into the first lock hole 10d causes the reduced diameter portion R11 of the lock pin R1 to press the expanded diameter portion 10d1 of the first lock hole 10d so that the nozzle touch block 10 is positioned accurately. As a result, the nozzle touch block 10 is moved and corrected to the correct stop position.

[0059] In this way, when the lock pin R1 is inserted into the first lock hole 10d of the nozzle touch block 10 to a predetermined position (predetermined depth), the nozzle touch block 10 is fixed in an accurate stopping position while being pressed toward the manifold 4 by the lock pin R1, and resin leakage does not occur between the nozzle touch block 10 and the base member B of the manifold 4.

[0060] When molding a black molded product, the third drive unit 27 in the valve body 21 is operated to move the first valve pin 25 upward, thereby opening the first gate 22a of the first resin passage 22 that communicates with the first hot runner 5, while the fourth drive unit 28 is operated to keep the second gate 23a of the second resin passage 23 that communicates with the second hot runner 6 closed.

[0061] Furthermore, if a white molded product is molded in the manner described below before molding a black molded product, the second hot runner 6 is filled with white molten resin. The upper end opening of the inlet 6a of the second hot runner 6 is connected to the first open port 15a of the first open path 15 of the nozzle touch block 10. The molten resin in the second hot runner 6 is smoothly discharged to the outside through the first open path 15 as needed, preventing the molten resin in the second hot runner 6 from pushing up the nozzle touch block 10. This maintains close contact between the nozzle touch block 10 and the base member B of the manifold 4, preventing resin leakage from between the nozzle touch block 10 and the base member B of the manifold 4.

[0062] Next, the nozzle 20 of the injection unit is pressed against the first sprue bushing 11, and black-colored molten resin is injected from the nozzle 20 of the injection unit through the first sprue bushing 11 and into the first inlet passage 13. The molten resin flows from the first inlet passage 13 through the inlet 5a of the first hot runner 5 and into the first hot runner 5. As described above, the first inlet 13a of the first inlet passage 13 of the nozzle touch block 10 and the upper end opening of the inlet 5a of the first hot runner 5 are tightly and accurately attached to each other. Therefore, the molten resin can be introduced into the first hot runner 5 without resin leakage from the joint between the first inlet 13a of the first inlet passage 13 of the nozzle touch block 10 and the upper end opening of the inlet 5a of the first hot runner 5.

[0063] Furthermore, the molten resin introduced into the first hot runner 5 is introduced from the outlet of the first hot runner 5 into the first resin passage 22 of the valve body 21, and then flows from the first gate 22a of the first resin passage 22 through the common passage 24 to fill the cavity 3, thereby injection-molding a black molded product.

[0064] To obtain a white molded product, the third drive unit 27 of the valve body 21 is operated to move the first valve pin 25 downward, thereby closing the first gate 22a of the first resin passage 22, which communicates with the first hot runner 5. Furthermore, the fourth drive unit 28 is operated to move the second valve pin 26 upward, thereby opening the second gate 23a of the second resin passage 23, which communicates with the second hot runner 6. The second drive unit R is operated to retract (retract) the lock pin R1, which is then removed from the first lock hole 10d of the nozzle touch block 10, rendering the nozzle touch block 10 movable. The first drive unit is then operated to retract the piston rod 19, thereby moving the nozzle touch block 10 and positioning the second sprue bushing 12, which protrudes from its upper surface, directly below the nozzle 20 of the injection unit (see FIGS. 2(b), 5, 7(b), and 8(b)).

[0065] Next, the second drive device R is driven to extend (move forward) the lock pin R1, and the lock pin R1 is inserted into the second lock hole 10e of the nozzle touch block 10, fixing the nozzle touch block 10 at a predetermined position on the movement path. In this state, the second inlet 14a of the second inlet passage 14 of the nozzle touch block 10 communicates with the upper opening of the inlet 6a of the second hot runner 6, and the second open port 16a of the second open passage 16 of the nozzle touch block 10 communicates with the upper opening of the inlet 5a of the first hot runner 5.

[0066] When the lock pin R1 is inserted into the second lock hole 10e of the nozzle touch block 10, the nozzle touch block 10 is fixed in an accurate stopping position by being pressed toward the manifold 4 by the lock pin R1, as described above, and no resin leakage occurs between the nozzle touch block 10 and the base member B of the manifold 4.

[0067] Next, the nozzle 20 of the injection unit is pressed against the second sprue bushing 12, and white-colored molten resin is injected from the nozzle 20 of the injection unit through the second sprue bushing 12 and into the second inlet passage 14. The molten resin flows from the second inlet passage 14 through the inlet 6a of the second hot runner 6 and into the second hot runner 6. As described above, the second inlet 14a of the second inlet passage 14 of the nozzle touch block 10 and the upper opening of the inlet 6a of the second hot runner 6 are tightly and accurately attached to each other. Therefore, the molten resin can be introduced into the second hot runner 6 without resin leakage from the joint between the second inlet 14a of the second inlet passage 14 of the nozzle touch block 10 and the upper opening of the inlet 6a of the second hot runner 6.

[0068] Furthermore, the molten resin introduced into the second hot runner 6 is introduced from the outlet of the second hot runner 6 into the second resin passage 23 in the valve body 21, and then flows from the second gate 23a of the second resin passage 23 through the common passage 24 to fill the cavity 3, thereby producing a white molded product by injection molding.

[0069] Furthermore, if a black molded product is molded in the manner described above before molding a white molded product, the first hot runner 5 will be filled with black molten resin. The upper end opening of the inlet 5a of the first hot runner 5 is connected to the second open port 16a of the second open path 16 of the nozzle touch block 10. The molten resin in the first hot runner 5 is smoothly discharged to the outside through the second open path 16 as needed, preventing the molten resin in the first hot runner 5 from pushing up the nozzle touch block 10. Therefore, adhesion between the nozzle touch block 10 and the base member B of the manifold 4 is maintained, preventing resin leakage from between the nozzle touch block 10 and the manifold 4.

[0070] The above-mentioned injection molding apparatus has been described as an injection molding apparatus capable of injection molding molded products of two different colors, such as white and black, but it is also possible to configure the injection molding apparatus to be capable of producing molded products of three or more different colors by providing three or more inlet passages in the nozzle touch block 10 and providing the manifold with multiple hot runners that are respectively connected to these inlet passages.

[0071] Furthermore, in the above-mentioned injection molding apparatus, the nozzle touch block 10 is placed on the top surface of the manifold 4 and moved horizontally, but the nozzle touch block 10 may also be placed on the side of the manifold 4 and moved vertically.

[0072] (Cross-reference to related applications) This application claims priority to Japanese Patent Application No. 2024-61524, filed on April 5, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0073] The injection molding apparatus of the present invention can easily produce molded products of different colors without resin leakage by accurately positioning the inlet of the introduction passage located directly below the injection unit at the inlet of the hot runner corresponding to this introduction passage.

[0074] 10e Lock hole R1 Lock pin R11 Reduced diameter portion R12 Axis center B Base member C Center of lock hole 1 Fixed mold 2 Moving mold 3 Cavity 4 Manifold 5 First hot runner 6 Second hot runner 9 Guide member 10 Nozzle touch block 10d First lock hole 10d1 Expanded diameter portion 10e Second lock hole 10e1 Expanded diameter portion 11 Sprue bushing 12 Sprue bushing 13 First inlet passage 13a First inlet port 14 Second inlet passage 14a Second inlet port 15 First open passage 15a First open port 16 Second open passage 16a Second open port 19 Piston rod 20 Nozzle

Claims

1. An injection molding apparatus comprising: an injection unit having a nozzle for supplying molten resin; a fixed mold; a movable mold which forms a cavity between its opposing surfaces and the fixed mold; a manifold disposed on the fixed mold and having a plurality of independent hot runners therein through which molten resins of different colors respectively flow; a guide member disposed on the manifold; a nozzle touch block which is disposed movably along the guide member and has a plurality of introduction paths corresponding to each of the plurality of hot runners, the introduction paths communicating with the corresponding hot runners when the nozzle touch block is moved along the guide member to face directly below the nozzle of the injection unit during injection molding; and a lock pin which is removably inserted into a lock hole formed in the nozzle touch block with any of the introduction paths of the nozzle touch block communicating with the hot runner corresponding to the introduction path, and which fixes the nozzle touch block on its movement path with the introduction port of the introduction path positioned relative to the hot runner.

2. The injection molding apparatus described in claim 1, characterized in that the nozzle touch block has the lock hole formed in each of the portions facing the lock pin when any of the multiple introduction paths is positioned directly below the nozzle of the injection unit.

3. An injection molding apparatus as described in claim 1 or claim 2, characterized in that the lock hole of the nozzle touch block has an enlarged diameter portion that gradually expands in diameter toward its open end, and the tip of the lock pin is formed into a reduced diameter portion that gradually reduces in diameter toward the tip, and when the lock pin is inserted into the lock hole, it abuts against the inner surface of the lock hole, and the nozzle touch block is configured to be able to move to a predetermined position along the guide member.

4. The injection molding apparatus according to claim 3, wherein the lock pin is offset toward the manifold with respect to the lock hole of the nozzle touch block.

5. An injection molding apparatus as described in claim 1 or claim 2, characterized in that the nozzle touch block has an opening path that communicates with the hot runner corresponding to another introduction path and opens the hot runner to the outside when any of the multiple introduction paths is located directly below the nozzle of the injection unit.

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