Gate needle valve device and control method of a multi-gate hot runner injection mold

Abstract

The present invention discloses a gate needle valve device and a control method for a multi-gate hot runner injection mold. When the molten resin filling the cavity reaches the position of the subsequent gate, it directly acts on the valve needle at the corresponding subsequent gate position, and the valve needle retreats to the sensing position due to the pressure of the molten resin. The induction contactor emits an induction signal, and the piston in the cavity drives the valve needle to move to open and close the gate according to the induction signal of the induction contactor.

Description

Technical Field

[0001] The present invention relates to a needle valve device for controlling the gates of a multi-gate hot runner injection mold, and particularly to a needle valve device for a multi-gate hot runner injection mold and a control method thereof, which can timely open and close the needle valves of multiple gates according to the flow direction of the molten resin inside to fill the cavities of a multi-gate mold. Background Art

[0002] Considering the fluidity of the molten resin filled into the cavity of a hot runner injection mold, in order to properly distribute the molten resin inside the cavity, there is a hot runner injection mold with multiple gates in one cavity. Such a multi-gate hot runner injection mold uses a piston device driven by compressed air to move forward / backward, and a forward / backward valve needle to open and close the gate. A 'piston-operated' gate needle valve device is used (refer to Patent Document 1 KR10-0448373B).

[0003] In the conventional action mode of the needle valve of a multi-gate hot runner injection mold, according to the sequential control signal preset by the controller, the gate needle valves are opened and closed in sequence by a'sequence' control method.

[0004] That is, as shown in Patent Document 1, according to the sequential control method of the gate needle valve, after the first gate is opened first, after a certain time (delay time) preset by the controller, the gate (the second gate) closest to the first gate in the molten resin flow path is opened. For the sequential control, the timing of opening the subsequent gate (the second gate) is determined in advance through computer simulation considering the flow rate of the resin inside the cavity to evenly distribute and fill the inside of the cavity.

[0005] However, for this kind of gate needle valve opening and closing control based on computer simulation, due to the difference in the actual flow direction of the molten resin inside the cavity, when the molten resin filled through each gate converges inside the cavity, problems such as weld lines are formed, resulting in poor injection molding.

[0006] To solve such problems, Patent Document 2 KR10-1285371B discloses detecting the actual internal temperature and pressure of the cavity, judging the position where the molten resin arrives, and opening and closing the gate according to the detection result.

[0007] However, as shown in the patent document 2KR10-1285371B, the sensors for the gate opening and closing control method using pressure sensors and temperature sensors are relatively expensive and cannot be set at each required position. The minimum number of sensors is set at the positions where sensors are most needed. When the sensors, positions, and quantities are incorrect or insufficient, the gate opening timing is inconsistent with the actual driving of the molten resin, resulting in molding defects such as 'weld lines' during injection molding. Moreover, it is difficult to set sensors in the mold, and there are disadvantages that limit the sensor setting. Summary of the Invention

[0008] The main technical problem to be solved by the present invention is to provide a gate needle valve device and a control method for a multi-gate hot runner injection mold. The present invention is to solve the problems of the prior art. When the molten resin that first flows into the cavity through the gate of the multi-gate hot runner injection mold actually reaches the gate position later, the gate is opened, and the purpose is to provide a control for the gate needle valve device.

[0009] In addition, the purpose of the present invention is to provide a multi-gate hot runner injection mold with at least one or more gates in one cavity. The molten resin that first fills the cavity through the gate is opened at the correct time point when it actually reaches the gate position in the cavity later, so that the molten resin that subsequently fills through the gate merges with the previously filled molten resin, and a method for controlling the gate needle valve device is provided.

[0010] To solve the above technical problems, a technical solution adopted by the present invention is:

[0011] Provide a gate needle valve device for a multi-gate hot runner injection mold, characterized by including: a cavity (2), a gate (3), a valve needle guide sleeve (12a) located between a fixed mold (1A) and a movable mold (1B), a nozzle (10) provided in the fixed mold, a valve needle (20), an induction contactor (70) for sensing whether the molten resin reaches the position (G) of the gate (3), and a controller that issues a gate opening and closing signal according to the arrival signal of the induction contactor (70);

[0012] A plurality of gates (3) are communicatively provided on the cavity (2), and a nozzle (10) is correspondingly provided on each gate (3). The valve needle guide sleeve (12a) is disposed through the nozzle (10) in the length direction and is communicatively connected to the gate (3); a runner (5) is provided in the manifold plate (4), a resin passage (13) is provided in the nozzle (10), and the resin passage (13) is communicatively connected to the runner (5) and the valve needle guide sleeve (12a) respectively. The runner (5) and the resin passage (13) convey the molten resin to each gate (3);

[0013] A valve needle (20) is movably arranged inside a valve needle guide sleeve (12a). When the valve needle (20) is in the maximum forward position, the tip (21) at the lower end of the valve needle (20) completely closes the gate (3). When the valve needle (20) is in the maximum backward position, the tip (21) at the lower end of the valve needle (20) completely opens the gate (3).

[0014] A piston (40) is located inside a piston device (30). The piston (40) drives the valve needle (20) to move back and forth between the maximum forward position and the maximum backward position according to the gate opening and closing signal of the controller.

[0015] An induction part (26) is arranged on the upper part of the valve needle (20), so that the induction contactor (70) obtains the position relationship information of the molten resin (M) reaching the gate (3) according to the detected position of the induction part (26).

[0016] In a preferred embodiment of the present invention, the valve needle (20) includes a valve needle body (24), a tip (21), a head (22) arranged at the upper end of the valve needle body (24), and a connecting part (25) connected to the head (22). An extension rod (27) is arranged at the upper end of the connecting part (25), and an induction part (26) for cooperating with the induction operation of the induction contactor (70) is connected to the upper end of the extension rod (27).

[0017] In a preferred embodiment of the present invention, a cylinder (31) drives the piston (40) to move forward or backward in the internal space to drive the valve needle (20) to move to the maximum forward position or the maximum backward position. A connecting part seat groove (42) for connecting the connecting part (25) is arranged inside a central shaft (41), so that when the valve needle (20) moves between the maximum forward position and the induction position (P1) of the induction contactor (70), the piston (40) remains stationary, and a corresponding gap (H) is formed between the inner rear wall surface (42a) of the connecting part seat groove (42) and the hanging platform (25a) of the connecting part (25) according to the distance between the induction position (P1) and the maximum forward position.

[0018] In a preferred embodiment of the present invention, a cylinder partition wall (32) is arranged inside the cylinder (31). The cylinder partition wall (32) divides the internal space of the cylinder (31) into an upper piston chamber (33U) and a lower piston chamber (33L). The piston (40) is movably arranged inside the upper piston chamber (33U), and a piston auxiliary (50) is arranged inside the lower piston chamber (33L). The compressed air flowing into the lower space drives the piston (40) to retreat through the piston auxiliary (50), so that the gap (H) is formed inside the connecting part seat groove (42).

[0019] In a preferred embodiment of the present invention, the resin channel (13) is a spiral groove provided on the outer side of the nozzle (10) in a spiral shape. The upper end of the spiral groove communicates with the flow channel (5), and the connection path (15) communicates with the valve needle guide sleeve (12a) and the upper end of the spiral groove respectively.

[0020] In a preferred embodiment of the present invention, the resin channel (13) and the valve needle guide sleeve (12a) are two separate channels provided in the nozzle body (12), and the resin channel (13) communicates with the connection path (15) and the flow channel (5) respectively.

[0021] In a preferred embodiment of the present invention, the induction contactor (70) senses the positional relationship between the sensing position (P1) and the retracted extension rod (27), and is a return switch and a proximity switch that emits a gate arrival signal.

[0022] A control method for a gate needle valve device of a multi-gate hot runner injection mold, the steps of which include:

[0023] The piston (40) drives the valve needle (20) to retract to the maximum retracted position to open the gate (3), and the molten resin (M) first fills the inside of the cavity (2) through the first gate.

[0024] When the molten resin (M) in the cavity (2) reaches the position of the subsequent gate (G) in the closed state, the valve needle (20) corresponding to the subsequent gate position (G) retracts to the sensing position (P1) along with the pressure of the molten resin (M). At this time, the tip (21) keeps the gate (3) closed.

[0025] The induction contactor (70) corresponding to the subsequent gate position (G) detects the valve needle (20) retracted to the sensing position (P1), and then sends a signal that the molten resin has reached the gate position to the controller; after receiving the signal that the molten resin has reached the gate position, the controller inputs compressed air into the piston chamber corresponding to the subsequent gate position (G), drives the piston to retract to the maximum retracted position, opens the gate, and the molten resin enters the cavity (2) from this gate and merges with the previous molten resin.

[0026] In a preferred embodiment of the present invention, when the cavity is filled with molten resin, the first piston drives the first valve needle to advance to close the first gate, and then the second piston drives the second valve needle to advance to close the second gate to complete the injection molding.

[0027] In a preferred embodiment of the present invention, when the molten resin (M) inside the cavity (2) pushes the valve needle (20) to move to the sensing position (P1), the tip (21) keeps the gate (3) closed.

[0028] In a preferred embodiment of the present invention, when the valve pin (20) opens the gate (3), the controller issues a gate open signal, and when the valve pin (20) closes the gate (3), the controller issues a gate close signal.

[0029] The beneficial effects of the present invention are as follows: The molten resin that first fills the cavity through the gate is allowed to flow together with the molten resin that subsequently fills through the gate at the correct time point when the molten resin actually reaches the gate position in the cavity. By filling the molten resin through multiple gates and allowing them to flow together at different time points, there is no weld mark or other injection molding defects, and the injection molding is of good quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, where:

[0031] Figure 1 is a schematic cross-sectional structure diagram of a preferred embodiment of the gate needle valve device of a multi-gate hot runner injection mold of the present invention;

[0032] Figure 2 is Figure 1 an enlarged view of the 'X' part in the gate needle valve device of a multi-gate hot runner injection mold of the present invention;

[0033] Figure 3 is a schematic structural diagram of the valve pin in the gate needle valve device of a multi-gate hot runner injection mold of the present invention;

[0034] Figure 4 is an enlarged structural diagram of the piston device in the gate needle valve device of a multi-gate hot runner injection mold of the present invention;

[0035] Figure 5 is a schematic structural diagram of a preferred embodiment of the nozzle of the gate needle valve device of a multi-gate hot runner injection mold of the present invention;

[0036] Figure 6 is a schematic structural diagram of another preferred embodiment of the nozzle of the gate needle valve device of a multi-gate hot runner injection mold of the present invention;

[0037] Figure 7 is a schematic structural diagram of the induction operation preparation stage of the gate needle valve device of a multi-gate hot runner injection mold of the present invention;

[0038] Figure 8It is a schematic structural diagram of the triggering and sensing stage of the gate needle valve device of a multi-gate hot runner injection mold of the present invention;

[0039] Figure 9 It is a schematic structural diagram of the molten resin confluence stage in the gate needle valve device of a multi-gate hot runner injection mold of the present invention;

[0040] Figure 10 It is a schematic structural diagram of the state where the gate is closed by the valve needle after the cavity is filled with molten resin as shown. Detailed implementation manners

[0041] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0042] Please refer to Figures 1-10 , the embodiments of the present invention include:

[0043] Figure 1 The multi-gate hot runner injection mold provided with a gate needle valve device in the present invention as shown. Figure 1 In the drawings, the symbols '1A' and '1B' refer to the fixed mold and the moving mold of each mold respectively, '2' refers to the cavity, '3' refers to the gate, '4' refers to the manifold plate, '5' refers to the runner of the manifold plate, '6' refers to the upper panel, and '7' refers to the cylinder head.

[0044] The gate needle valve device of a multi-gate hot runner injection mold of the present invention includes a cavity (2), a gate (3), a valve needle guide sleeve (12a), a nozzle (10) provided in the fixed mold, a valve needle (20), an induction contactor (70) for sensing whether the molten resin reaches the position (G) of the gate (3), and a controller for sending a gate opening and closing signal according to the arrival signal of the induction contactor (70) between the fixed mold (1A) and the moving mold (1B).

[0045] A plurality of gates (3) are communicatively provided on the cavity (2), and a nozzle (10) is correspondingly provided on each gate (3). The valve needle guide sleeve (12a) is arranged through the nozzle (10) in the length direction and is communicatively connected with the gate (3); a runner (5) is arranged in the manifold plate (4), a resin channel (13) is arranged in the nozzle (10), the resin channel (13) is respectively communicatively connected with the runner (5) and the valve needle guide sleeve (12a), and the runner (5) and the resin channel (13) convey the molten resin to each gate (3).

[0046] A gate needle valve device (100) for opening and closing each gate (3) is provided on the fixed mold (1A) of the injection mold.

[0047] A valve needle guide sleeve (12a) is movably provided with a valve needle (20). When the valve needle (20) is in the maximum forward position, the tip (21) at the lower end of the valve needle (20) completely closes the gate (3). When the valve needle (20) is in the maximum backward position, the tip (21) at the lower end of the valve needle (20) completely opens the gate (3).

[0048] A piston (40) is located within a piston device (30). The piston (40) drives the valve needle (20) to move back and forth between the maximum forward position and the maximum backward position according to the gate opening and closing signal of the controller.

[0049] The controller issues a gate opening signal to open the gate with the valve needle or issues a gate closing signal to close the gate with the valve needle.

[0050] An induction portion (26) is provided at the upper part of the valve needle (20), such that the induction contactor (70) obtains the position information of the molten resin (M) and the gate (3) according to the detected position of the induction portion (26).

[0051] When the molten resin (M) inside the cavity (2) reaches the gate position (G), the pressure of the molten resin (M) drives the valve needle (20) to move to the sensing position (P1) and the tip (21) remains closed to the gate (3), such that the induction contactor (70) detects the induction portion (26) and issues a signal that the molten resin (M) has reached the gate position (G).

[0052] The controller receives the signal that the molten resin (M) has reached the gate position (G) issued by the induction contactor (70), and issues a gate opening signal. The piston device (30) and the piston (40) drive the valve needle (20) to retreat to the maximum backward position according to the gate opening signal to open the gate (3).

[0053] Figure 2 As shown, the gate needle valve device (100)(100A) of the present invention includes a nozzle (10), a valve needle (20) for opening and closing the gate (3), a piston device (30) for driving the valve needle (20) to retreat or advance to open and close the gate (3), and an induction contactor (70) for sensing the molten resin reaching the gate position. When the molten resin fills the cavity (2) and reaches the position formed by the gate (3) (hereinafter referred to as the 'gate position' (G)), the induction contactor (70) is triggered.

[0054] Figure 5As shown, the nozzle (10) includes a body (11), a through-hole (11a) disposed longitudinally within the body (11), and a nozzle body (12) having a valve needle guide sleeve (12a) longitudinally therethrough. The nozzle body (12) is fixed within the through-hole (11a) of the body (11), and the lower end of the through-hole (11a) communicates with a nozzle tip (14).

[0055] There is a resin channel (13) around the nozzle body (12). The resin channel (13) communicates with the runner (5) on the manifold plate (4) and each gate (3), guiding the molten resin in the runner (5) to the gate (3).

[0056] In this embodiment, the resin channel (13) can be a spiral groove disposed around the nozzle body (12). The outlet of the resin channel (13) is connected to a connection path (15) disposed inside the nozzle tip (14). The connection path (15) and the resin channel (13) formed within the nozzle body (12) communicate with the gate (3), directly guiding the molten resin to the gate (3) through the runner (5) and the connection path (15), without the need to convey the molten resin through the valve needle guide sleeve (12a).

[0057] The connection path (15) is located within the nozzle tip (14) of the nozzle (10). The amount of molten resin dripping into the connection path (15) is small, so the pressure is not high, which does not interfere with the sensing operation in the retracting direction of the valve needle (20) (detailed description follows). That is, the resin channel (13) is formed around the nozzle body (12), and the sensing of the valve needle (20) is not affected by the pressure of the molten resin supplied to the gate (3).

[0058] Different from Figure 5 in the embodiment, the resin channel (13) and the valve needle guide sleeve (12a) are two separate channels disposed within the nozzle body (12), and the resin channel (13) is respectively connected to the connection path (15) and the runner (5).

[0059] As Figure 6 shown, the different channels formed by the resin channel (13) and the valve needle guide sleeve (12a) aim to: in the prior art, the valve needle guide sleeve (12a) and the resin channel are used in common, and the pressure of the molten resin filling the inside of the valve needle guide sleeve (12a) hinders the opening of the gate by the valve needle (forward direction). The pressure of the molten resin reaching the gate position inside the cavity (2) is for the sensing operation of the valve needle (20), eliminating the problem of hindrance to retraction.

[0060] A valve needle (20) is slidably disposed within the valve needle guide sleeve (12a) of the nozzle body (12).

[0061] Figure 3 As shown, the valve pin (20) includes a valve pin body (24). At the front end of the valve pin body (24), there is a pointed head (21) for opening and closing the gate (3), and at the rear end of the valve pin body (24), there is a head (22). At the front end of the extension rod (27), there is a connecting portion (25) connected to the head (22), and at the rear end of the extension rod (27), there is a sensing portion (26).

[0062] The valve pin body (24) passes through a central through-hole (16a) on the inner nozzle body (16) located in the manifold plate (4) and is inserted into a valve pin guide sleeve (12a) inside the nozzle body (12). The inner nozzle body (16) is provided with a resin path (17) that communicates with the runner (5) and the resin passage (13), so that the molten resin provided by the runner (5) of the manifold plate (4) can be guided to the resin passage (13) of the nozzle body (12) through the resin path (17).

[0063] The head (22) of the valve pin body (24) is connected and arranged in a piston device (30) on the upper panel (6), and the extension rod (27) of the extended valve pin (20) is connected to the head (22) in a coaxial direction.

[0064] As Figure 2 and Figure 4 shown, a cylinder (31) connected to the upper mold panel (6) is provided inside the piston device (30). Inside the cylinder (31), there is a cylinder partition wall (32) extending in the inner radius direction from the inner side wall. The cylinder partition wall (32) divides the internal space of the cylinder (31) into an upper piston chamber (33U) and a lower piston chamber (33L). A central through-hole (32a) in the central axis direction is formed in the center of the cylinder partition wall (32).

[0065] The upper piston chamber (33U) is provided with a piston (40), and the lower piston chamber (33L) is provided with a piston assist (50).

[0066] When the cylinder operates forward or backward in the upper piston chamber (33U), the piston (40) drives the valve pin (20) to move to the maximum forward position or the maximum backward position. A connecting portion seat groove (42) is provided inside the central shaft (41), and the connecting portion seat groove (42) is connected to the connecting portion (25) of the valve pin (20).

[0067] According to the sensed movement distance (the distance that the valve pin moves to the sensing position as the molten resin pressure reaches the gate position), a certain gap (H) is correspondingly formed between the inner rear wall surface (42a) of the connecting portion seat groove (42) and the hanging platform (25a) of the connecting portion (25).

[0068] Figure 4As shown, compressed air flows into the lower space (50L) of the piston assist (50). According to this compressed air, as the piston assist (50) retracts, the piston (40) retracts. Under the action of its own gravity, the valve needle causes a gap (H) to be formed between the inner rear wall surface (42a) and the hanging platform (25a) inside the connecting portion seat groove (42). As described above, when a gap (H) is formed between the piston (40) and the valve needle (20) inside the connecting portion seat groove (42), when the inductive contactor (70) senses and operates, the piston (40) does not move, and only the valve needle (20) moves to the sensing position (P1).

[0069] When the piston (40) moves to the maximum forward position and the valve needle (20) moves to the maximum forward position, the pointed tip (12) provided at the front end of the valve needle (20) completely closes the gate (3). When the piston (40) retracts and the valve needle (20) moves to the maximum retracted position, the pointed tip (12) completely opens the gate (3), and molten resin is filled into the cavity (2) through the gate (3).

[0070] As described above, before the valve needle (20) retracts to the maximum retracted position according to the retraction operation of the piston (40) and completely opens the gate (3), the molten resin first passes through the first gate. When the molten resin previously filled inside the cavity reaches the position of the subsequent gate, the induction device corresponding to this gate position is triggered.

[0071] When the pointed tip (21) of the valve needle (20) is in a state where the gate (3) is completely closed, the molten resin filled into the cavity (2) reaches the 'gate position in the cavity' (hereinafter referred to as reaching the 'gate position' (G)). The molten resin increases the pressure on the bottom surface of the pointed tip (21) inside the cavity (2), and the valve needle (20) moves to the'sensing position' (P1) to indicate that the molten resin has reached the 'gate position' (G).

[0072] The pressure of the molten resin pushes the valve needle (20) towards the'sensing position' (P1). The gap (H) formed between the inner rear wall surface (42a) and the hanging platform (25a) allows the valve needle (20) to retract, and thus the piston (40) does not retract, causing the pointed tip (21) of the valve needle (20) to retract to a state before the gate (3) is closed and the gate is opened. At the same time, the sensing portion (26) on the extension rod (27) moves to the sensing position (P1).

[0073] When the sensing portion (26) of the extension rod (27) retracts to the sensing position (P1), the inductive contactor (70) provided on the cylinder head (7) senses the sensing portion (26) and sends a signal that the molten resin inside the cavity (2) has reached the gate to the controller (not shown).

[0074] The inductive contactor (70) can adopt a return sensor that emits a signal indicating the arrival of the molten resin gate by contacting the induction part (26). The inductive contactor (70) can adopt a 'proximity sensor' that emits an induction signal by approaching and non-contact with the induction part (26).

[0075] When the controller receives the'molten resin gate arrival signal' sent by the inductive contactor (70), the solenoid valve receives the open signal sent by the controller to open the air passage A, and compressed air flows into the lower space of the piston (40) through the air passage A; the piston (40) retracts, and the valve needle (20) located at the induction position (P1) also continues to retract to the maximum retraction position to fully open the gate (3); then, the molten resin in the connection path (15) fills into the cavity (2) through the gate (3) and merges with the molten resin that has been filled and flowing inside the cavity before.

[0076] Next, the gate needle valve operation control method of the multi-gate hot runner injection mold according to the present invention will be described.

[0077] Figure 7 As shown, the piston device (30) drives the piston (40) to advance, and the gate (3) is completely closed by the valve needle (20). At this time, the valve needle (20) needs to prepare for the induction operation: Compressed air is filled into the lower space of the piston auxiliary (50) through the air passage E, so that the piston auxiliary (50) drives the piston (40) to retract, and the retraction of the piston (40) forms a certain gap (H) between the hanging platform (25a) and the inside of the valve needle seat groove (42).

[0078] After that, the molten resin (M) filled into the cavity (2) moves to the gate position (G), the molten resin (M) exerts an upward pressure (in the arrow direction) on the tip (21), and the tip (21) and the induction part (26) retract simultaneously, and the induction part retracts to the induction position (P1).

[0079] When the inductive contactor (70) detects the induction part (26) that has moved to the induction position (P1), the inductive contactor (70) sends a signal indicating that the molten resin inside the cavity (2) has reached the gate position (G) to the controller.

[0080] Figure 9 As shown, when the controller receives the'molten resin reaches the gate position signal' sent by the inductive contactor (70), it sends an open signal to the solenoid valve needle valve that controls the opening and closing of the air passage A, and fills compressed air into the lower piston chamber (33L) below the piston (40) through the air passage A, so that the piston (40) retracts and drives the valve needle (20) to move to the maximum retraction position to open the gate (3), and the resin passage (13) fills the molten resin into the cavity (2) through the connection path (15) and the gate (3).

[0081] In this state, the molten resin filled into the cavity (2) through the gate (3) flows within the cavity (2) and merges with the molten resin (M) previously filled in the cavity (2).

[0082] Figure 10 As shown, after the molten resin (M) in the cavity (2) is filled, the controller sends an open signal to the solenoid valve that controls the opening and closing of the control air passage B, causing the solenoid valve to open the air passage B, and delivering compressed air into the upper piston chamber (33U) to push the piston (40) forward. The piston (40) drives the valve needle (20) to move to the maximum forward position to close the gate (3). Specific Embodiment 1

[0084] A gate needle valve device for a multi-gate hot runner injection mold has one cavity (2), and there are 2 gates (3) on one cavity (2). In the order of opening, the first opened gate is the 'First Gate' (3A), and the subsequently opened gate is the 'Second Gate' (3B).

[0085] The gate needle valve device for opening and closing the first gate (3A) is called the first gate needle valve device (100A), and the gate needle valve device for opening and closing the second gate (3B) is called the second gate needle valve device (100B).

[0086] The first gate needle valve device (100A) and the second gate needle valve device (100B) can have the same structure. For the auxiliary materials with the same functions in the two gate needle valve devices (100A, 100B), the same names and symbols can be used. When differentiating the auxiliary materials of the first gate needle valve device (100A) and the second gate needle valve device (100B), the suffix 'A' is added to the symbol of the auxiliary materials of the first gate needle valve device (100A), and the suffix 'B' is added to the symbol of the auxiliary materials of the second gate needle valve device (100B).

[0087] The usage steps of a gate needle valve device for a multi-gate hot runner injection mold include:

[0088] 1. The first piston in the first piston device and the second piston in the second piston device advance, causing the first valve needle and the second valve needle to advance to the maximum forward position to close the first gate and the second gate;

[0089] 2. Supply compressed air to the lower piston chamber of the first piston device, and the first piston in the first piston device retreats, driving the first valve needle to retreat to the maximum backward position to fully open the first gate, and the resin passage fills the molten resin into the cavity;

[0090] 3. Before the molten resin filled into the cavity from the first gate reaches the position of the second gate, fill compressed air into the lower side space assisted by the second piston in the second piston device to prepare the second valve needle for induction operation;

[0091] 4. When the molten resin in the cavity reaches the position of the second gate, the molten resin presses the second valve needle in the second piston device, causing the valve needle to retract to the induction position;

[0092] 5. The induction contactor senses the induction part retracted to the induction position and sends a signal that the molten resin has reached the second gate to the controller;

[0093] 6. The controller receives the signal that the molten resin has reached the second gate and controls the solenoid valve to fill compressed air into the lower piston chamber of the second piston. The second piston retracts and drives the second valve needle to move to the maximum retracted position, opening the second gate;

[0094] 7. The molten resin is filled into the cavity through the second gate, and the molten resin filled through the second gate and the molten resin filled through the first gate merge;

[0095] 8. When the cavity is filled with the molten resin, the first piston drives the first valve needle forward to close the first gate, and then the second piston drives the second valve needle forward to close the second gate, completing the injection molding.

[0096] The beneficial effects of the gate needle valve device and control method of the multi-gate hot runner injection mold of the present invention are as follows: The molten resin first filled into the cavity through the gate opens the gate at the correct time point when the molten resin actually reaches the gate position in the cavity later, allowing the molten resin filled through the gate later and the molten resin filled first to merge. The molten resin is filled through multiple gates in sequence and merges at different time points, and there is no injection molding defect such as weld marks in the injection molding.

[0097] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A gate needle valve device for a multi-gate hot runner injection mold, characterized in that, it includes: a cavity (2), a gate (3), a valve needle guide sleeve (12a), a nozzle (10) disposed in the fixed mold, a valve needle (20), an induction contactor (70) for sensing whether the molten resin reaches the position (G) of the gate (3), and a controller for sending a gate opening / closing signal according to the arrival signal of the induction contactor (70) between the fixed mold (1A) and the moving mold (1B); a plurality of gates (3) are communicatively provided on the cavity (2), and a nozzle (10) is correspondingly provided on each gate (3). The valve needle guide sleeve (12a) is disposed through the nozzle (10) in the length direction and communicates with the gate (3); a runner (5) is provided in the manifold block (4), and a resin passage (13) is provided in the nozzle (10). The resin passage (13) is respectively connected to the runner (5) and the valve needle guide sleeve (12a). The runner (5) and the resin passage (13) convey the molten resin to each gate (3); a valve needle (20) is movably disposed in the valve needle guide sleeve (12a). When the valve needle (20) is in the maximum forward position, the tip (21) at the lower end of the valve needle (20) completely closes the gate (3). When the valve needle (20) is in the maximum backward position, the tip (21) at the lower end of the valve needle (20) completely opens the gate (3); a piston (40) is located in a piston device (30), and the piston (40) drives the valve needle (20) to move back and forth between the maximum forward position and the maximum backward position according to the gate opening / closing signal of the controller; an induction part (26) is provided on the upper part of the valve needle (20), so that the induction contactor (70) obtains the position relationship information of the molten resin (M) reaching the gate (3) according to the detected position of the induction part (26).

2. The gate needle valve device for a multi-gate hot runner injection mold according to claim 1, characterized in that, the valve needle (20) includes a valve needle body (24), a tip (21), a head (22) disposed at the upper end of the valve needle body (24), and a connecting part (25) connected to the head (22). An extension rod (27) is provided at the upper end of the connecting part (25), and an induction part (26) for cooperating with the induction operation of the induction contactor (70) is connected to the upper end of the extension rod (27).

3. The gate needle valve device for a multi-gate hot runner injection mold according to claim 2, characterized in that, a cylinder (31) drives the piston (40) to move forward or backward in the internal space to drive the valve needle (20) to move to the maximum forward position or the maximum backward position. A connecting part seat groove (42) for connecting the connecting part (25) is provided in the central shaft (41). When the valve needle (20) moves between the maximum forward position and the induction position (P1) of the induction contactor (70), the piston (40) remains stationary, and a corresponding gap (H) is formed between the inner rear wall surface (42a) of the connecting part seat groove (42) and the hanging platform (25a) of the connecting part (25) according to the distance between the induction position (P1) and the maximum forward position.

4. The gate needle valve device of a multi-gate hot runner injection mold according to claim 3, characterized in that, a cylinder partition wall (32) is provided in the cylinder (31), and the cylinder partition wall (32) divides the internal space of the cylinder (31) into an upper piston chamber (33U) and a lower piston chamber (33L). The piston (40) is movably provided in the upper piston chamber (33U), and a piston assist (50) is provided in the lower piston chamber (33L). The compressed air flowing into the lower space drives the piston (40) to retreat through the piston assist (50), so that a gap (H) is formed in the connecting part seat groove (42).

5. The gate needle valve device of a multi-gate hot runner injection mold according to claim 1, characterized in that, the resin channel (13) is a spiral groove arranged on the outer side of the nozzle (10) in a spiral shape. The upper end of the spiral groove communicates with the runner (5), and the connection path (15) is respectively communicated with the valve needle guide sleeve (12a) and the upper end of the spiral groove.

6. The gate needle valve device of a multi-gate hot runner injection mold according to claim 1, characterized in that, the resin channel (13) and the valve needle guide sleeve (12a) are two separate channels arranged in the nozzle body (12), and the resin channel (13) is respectively communicated with the connection path (15) and the runner (5).

7. The gate needle valve device of a multi-gate hot runner injection mold according to claim 1, characterized in that, the induction contactor (70) senses the positional relationship between the sensing position (P1) and the retracted extension rod (27), and is a return switch and a proximity switch that issue a signal that the gate has reached.

8. A control method for a gate needle valve device of a multi-gate hot runner injection mold, characterized in that the steps include: The piston (40) drives the valve needle (20) to retract to the maximum retracted position to open the gate (3), and the molten resin (M) first fills the inside of the cavity (2) through the first gate; When the molten resin (M) in the cavity (2) reaches the position (G) of the subsequent closed gate, the valve needle (20) corresponding to the subsequent gate position (G) retracts to the sensing position (P1) along with the pressure of the molten resin (M); The induction contactor (70) corresponding to the subsequent gate position (G) detects the valve needle (20) retracted to the sensing position (P1), and then sends a signal that the molten resin has reached the gate position to the controller. After receiving the signal that the molten resin has reached the gate position, the controller inputs compressed air into the piston chamber corresponding to the subsequent gate position (G), drives the piston to retract to the maximum retracted position, opens the gate, and the molten resin enters the cavity (2) from this gate and merges with the previous molten resin.

9. The control method for a gate needle valve device of a multi-gate hot runner injection mold according to claim 8, characterized in that, When the cavity is filled with molten resin, the first piston drives the first valve needle to advance to close the first gate, and then the second piston drives the second valve needle to advance to close the second gate to complete the injection molding.

10. A control method for the gate needle valve device of a multi-gate hot runner injection mold according to claim 8, characterized in that, when the molten resin (M) inside the cavity (2) pushes the valve needle (20) to move to the sensing position (P1), the tip (21) keeps the gate (3) closed.

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