Injection device of injection molding machine

Abstract

An injection device of an injection machine comprises an injection unit, a pre-plasticizing unit, a runner structure and an electric non-return mechanism, the injection unit comprises an injection material barrel and an injection plunger, the pre-plasticizing unit comprises a pre-plasticizing material barrel and a screw rod, and the runner structure is communicated with the two material barrels to form a molten plastic runner (L). An electric non-return mechanism composed of a driving source and a blocking piece is arranged in a flow channel, the driving source is in transmission connection with the blocking piece, in addition, the electric non-return mechanism is configured to open the flow channel in the pre-plasticizing stage and close the flow channel in the injection stage, and meanwhile movement of the blocking piece is actively controlled by the driving source. Due to the fact that a traditional passive structure is replaced by an electric active non-return structure, the influence of melt glue characteristics and mechanical abrasion can be eliminated, backflow of molten plastic is avoided, injection metering precision and product consistency are improved, energy consumption is reduced, the production period is shortened, and the strict requirement for precise manufacturing is met.

Description

Technical Field

[0001] This invention relates to the field of injection molding machine technology, and more specifically to an injection device for an injection molding machine. Background Technology

[0002] With the rapid upgrading of the precision manufacturing industry, injection molding technology is evolving rapidly towards automation, high efficiency, and energy saving. The market is placing increasingly stringent demands on the injection accuracy, response speed, and energy consumption control of injection molding machine injection units. Currently, mainstream injection molding machine injection units are mainly divided into two categories: electric drive and hydraulic drive. The former relies on an AC servo motor + ball screw transmission structure to achieve precision control, while the latter transmits power through a hydraulic system and is more suitable for high-load scenarios. However, both types of units face a common core technical bottleneck: the backflow problem of molten plastic during injection. This problem severely restricts the achievement of high-precision molding and low-energy production goals.

[0003] To suppress backflow, existing technologies generally employ mechanical check ring structures. The principle is that the pressure of the molten plastic itself forces the check ring to close, thereby blocking the backflow channel. However, this passive backflow prevention solution has significant shortcomings in practical applications: theoretically, the amount of refluxed melt injected each time should remain constant. However, due to multiple factors such as changes in melt viscosity, temperature fluctuations, check ring wear, and mechanical clearances, the actual backflow rate often fluctuates uncontrollably. This not only increases injection energy consumption and extends production cycles but also reduces injection metering accuracy, making it difficult to meet the stringent dimensional consistency requirements of precision plastic parts in fields such as medical and electronics.

[0004] To address the shortcomings of mechanical check rings, targeted improvements have been proposed in related technologies. For example, the invention patent application CN202311040913.1 (publication number CN117087114A) discloses an injection device for an injection molding machine. By setting a first limiting strip on the inner wall of the barrel and opening corresponding limiting grooves on the circumference of the check ring, the circumferential rotation of the check ring is restricted, reducing its friction and wear with the inner wall of the barrel. At the same time, the inclined second limiting strip promotes the flow of molten plastic, thereby improving the stability of the check ring to a certain extent.

[0005] However, this solution is essentially a passive anti-reverse mechanism of "mechanical limit + pressure coordination", which has not yet gotten rid of its dependence on the characteristics of melt and mechanical gaps. It still has problems such as slow response and difficulty in accurately controlling the backflow, and cannot achieve true zero backflow. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an injection device for an injection molding machine that integrates an electric anti-reverse device in the melt flow channel to enhance its adaptability and control capability under different process conditions, in order to address the above-mentioned technical status.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problem is: the injection device of the injection molding machine, including...

[0008] An injection unit having an injection barrel and an injection plunger axially movable within the injection barrel;

[0009] A pre-plasticizing unit having a pre-plasticizing cylinder and a screw rotatably disposed within the pre-plasticizing cylinder;

[0010] The flow channel structure includes a three-way connector, which is respectively sealed and connected to the front end of the injection barrel and the front end of the pre-plastic barrel to form a molten plastic flow channel that can connect the pre-plastic barrel and the injection barrel;

[0011] It also includes an electric anti-reverse mechanism, which includes a drive source and a sealing element driven by the drive source and movably disposed in the molten plastic flow channel;

[0012] The electric anti-reverse mechanism is configured such that, during the pre-plasticizing stage, the drive source drives the sealing element to open the molten plastic flow channel, allowing molten plastic to flow from the pre-plasticizing cylinder into the injection cylinder;

[0013] During the injection phase, the drive source drives the sealing element to close the molten plastic flow channel to prevent the molten plastic from flowing back towards the pre-plasticized cylinder.

[0014] To improve the reliability of the sealing fit, ensure that the electric anti-reverse mechanism can effectively block the molten plastic when closed, and enhance the adaptability of the device to different process conditions, preferably, the contact part between the sealing component of the electric anti-reverse mechanism and the molten plastic flow channel is provided with a sealing fit structure. The sealing fit structure includes a conical sealing surface or an annular sealing platform, and the sealing surface of the sealing component can fit against the inner wall of the molten plastic flow channel to improve the sealing reliability when the flow channel is closed.

[0015] To improve the integration and structural compactness of the electric anti-reverse mechanism and the pre-plasticizing unit, and to achieve a scheme for opening and closing the flow channel by axial movement of the valve core, preferably, the electric anti-reverse mechanism is a first electric anti-reverse device, which is installed on the pre-plastic cylinder front body connected in series in the molten plastic flow channel and connected to the front end of the pre-plastic cylinder; a pre-plasticizing connector is connected in series between the pre-plastic cylinder front body and the three-way connector, one end of the pre-plasticizing connector is sealed to the pre-plastic cylinder front body, and the other end is sealed to the three-way connector, so as to form a continuous flow channel from the pre-plastic cylinder to the three-way connector.

[0016] The sealing component is a first check valve core, which is axially movable and disposed in the front body of the pre-plastic cylinder; the driving source is a first motor transmission assembly, which drives the first check valve stem to swing through a transmission mechanism, thereby causing the first check valve core to move axially between the open and closed positions.

[0017] To achieve stable and precise transmission and control of the first electric check valve, preferably, the transmission mechanism of the first electric check valve includes a first lead screw, a first lead screw nut meshing with the first lead screw, and a first sliding sleeve assembly connected to the first lead screw nut; the first motor transmission assembly drives the first lead screw to rotate, the outer end of the first check valve rod is connected to the front end of the first sliding sleeve assembly, and the linear motion of the first sliding sleeve assembly drives the first check valve rod to swing, thereby driving the first check valve core to move axially.

[0018] To provide a more direct, compact, and easy-to-install and maintain electric check mechanism, preferably, the electric check mechanism is a second electric check device, which is installed on a first pre-plasticized check connector connected in series in the molten plastic flow channel. One end of the first pre-plasticized check connector is connected to the front end of the pre-plasticized cylinder, and the other end is connected to a three-way connector in the flow channel structure to form a continuous flow channel from the pre-plasticized cylinder to the three-way connector. The sealing element is a second check valve core, which is located in the first pre-plasticized check connector. The driving source is a second motor transmission device, which drives a second lead screw to rotate. The second lead screw cooperates with a screw hole provided on the second check valve core to drive the second check valve core to move up and down to realize the opening and closing of the flow channel.

[0019] In order to optimize the flow characteristics of the second check valve core and effectively prevent molten plastic from accumulating in the flow channel, preferably, the second check valve core is a flow channel type valve core, with an annular sealing slope set at an angle to the axis on its outer circumferential surface, and a first through inclined hole set at an angle to the axis at the front of the annular slope, so as to prevent molten plastic from stagnating and to clear the flow channel during the injection cycle.

[0020] To simplify the structure, utilize existing components to achieve the anti-reverse function, and avoid the influence of additional heat sources, preferably, the electric anti-reverse mechanism is a third electric anti-reverse device, which is installed on the side and the inner cavity of the pre-plastic cylinder motor base.

[0021] The flow channel structure is connected in series with a second pre-plastic anti-reverse connector. One end of the second pre-plastic anti-reverse connector is sealed to the front end of the pre-plastic cylinder, and the other end is sealed to the tee connector to form a continuous flow channel from the pre-plastic cylinder to the tee connector.

[0022] The sealing component is the front end of the pre-plasticized screw;

[0023] The driving source is a third motor transmission assembly. The third motor transmission assembly drives the pre-plasticized screw to move along the axis through a transmission mechanism. When the screw moves to the correct position, the front end of the pre-plasticized screw is in close contact with the flow channel end face of the second pre-plasticized anti-reverse connector, thereby closing the molten plastic flow channel. When the pre-plasticized screw retracts, the flow channel opens.

[0024] To achieve stable transmission for the axial movement of the drive screw, effectively converting rotational motion into linear motion and transmitting it to the screw, preferably, the transmission mechanism of the third electric anti-reverse device includes a third lead screw, a third lead screw nut meshing with the third lead screw, a second sliding sleeve assembly connected to the third lead screw nut, and a rocker arm; the third motor transmission assembly drives the third lead screw to rotate, one end of the rocker arm is connected to the second sliding sleeve assembly, and the other end is connected to the third sliding sleeve sleeved outside the screw; the linear motion of the second sliding sleeve assembly drives the rocker arm to swing, thereby driving the third sliding sleeve and the screw connected thereto to move along the axis.

[0025] To optimize the flow path of molten plastic at the front end of the injection plunger and prevent plastic from stagnating in the gap between the injection plunger and the front barrel, preferably, the outer periphery of the injection plunger is provided with an inclined annular stepped surface. The front part of the annular stepped surface has a second through inclined hole forming an angle with the axis of the injection plunger. On the outer periphery of the injection plunger in front of the second through inclined hole, there are also two flow channel grooves extending axially and with different widths. During pre-plasticizing, after the molten plastic enters the injection barrel, it flows into the front cavity of the injection barrel through the combined flow channel formed by the annular stepped surface, the second through inclined hole and the flow channel grooves. This can completely push the molten plastic that is stagnant at the front of the injection plunger after the last injection to the front cavity, effectively avoiding the accumulation of molten plastic due to long-term residence.

[0026] To achieve precise, rapid, and efficient transmission of the injection action and adapt to different load requirements, the injection unit preferably further includes an injection drive system for driving the injection plunger. The injection drive system is an electric drive system, which includes at least one set of direct-drive injection motors, a spline screw connected to the output end of the direct-drive injection motors via a spline, and a fourth screw nut meshing with the screw portion of the spline screw.

[0027] Compared with the prior art, the advantages of the present invention are as follows: By setting an electric anti-reverse mechanism including a drive source and a sealing component in the injection unit of the injection molding machine, and movably setting the sealing component in the molten plastic flow channel, and configuring the electric anti-reverse mechanism so that the drive source drives the sealing component to open the flow channel during the pre-plasticizing stage and the drive source drives the sealing component to close the flow channel during the injection stage, since the electric active control method replaces the traditional passive anti-reverse structure, it does not need to rely on the pressure of the molten plastic itself to achieve anti-reverse, thus eliminating the influence of melt viscosity, temperature fluctuation and mechanical wear on the anti-reverse effect, effectively preventing the molten plastic from flowing back towards the pre-plasticizing cylinder during the injection process, significantly improving the injection metering accuracy and product size consistency, while also having a faster response speed, stronger adaptability to different process conditions, reduced injection energy consumption and shortened production cycle, meeting the stringent requirements of injection molding in the precision manufacturing field. Attached Figure Description

[0028] Figure 1 This is an orthographic projection view of Example 1;

[0029] Figure 2 This is a side orthographic projection view of Example 1;

[0030] Figure 3 This is a schematic diagram of the AA cross-sectional structure of Example 1;

[0031] Figure 4 This is a schematic diagram of the BB cross-sectional structure of Example 1;

[0032] Figure 5 This is an orthographic projection view of Example 2;

[0033] Figure 6 This is a side orthographic projection view of Example 2;

[0034] Figure 7 This is a schematic diagram of the CC cross-sectional structure of Example 2;

[0035] Figure 8 This is an orthographic projection view of Example 3;

[0036] Figure 9 This is a side orthographic projection view of Example 3;

[0037] Figure 10 This is a schematic diagram of the DD cross-sectional structure of Example 3;

[0038] Figure 11 This is a schematic diagram of the EE cross-sectional structure of Example 3;

[0039] Figure 12 These are schematic diagrams of the injection of pre-plasticized molten plastic in Examples 1, 2, and 3;

[0040] Figure 13This is a schematic diagram of the flow of pre-plasticized molten plastic in Examples 1, 2, and 3;

[0041] Figure 14 This is a three-dimensional structural schematic diagram of Example 1;

[0042] Figure 15 This is a three-dimensional structural schematic diagram of Example 2;

[0043] Figure 16 This is a three-dimensional structural diagram of Example 3;

[0044] Figure 17 This is a schematic diagram of the molten plastic flow of the second check valve core in Example 2. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0046] Figures 1 to 17 The diagram shows three embodiments of the present invention. The core architecture of the injection device of the injection molding machine in Embodiments 1, 2 and 3 all include an injection unit, a pre-plasticizing unit, a flow channel structure and an electric anti-reverse mechanism.

[0047] The injection unit includes an injection cylinder 2a and an injection plunger 2b axially movable within the injection cylinder 2a, its core function being to inject molten plastic into the mold cavity; the pre-plasticizing unit includes a pre-plasticizing cylinder 4a and a screw 4b rotatably disposed within the pre-plasticizing cylinder 4a, its core function being to plasticize the raw material into molten plastic; the flow channel structure connects the pre-plasticizing cylinder 4a and the injection cylinder 2a, forming a molten plastic flow channel L, providing a passage for the molten plastic; the electric anti-reverse mechanism includes a drive source and a sealing element driven by the drive source and movably disposed within the molten plastic flow channel L; the sealing element and... All contact points of the molten plastic flow channel L are equipped with sealing structures, including conical sealing surfaces or annular sealing platforms. The sealing surface of the sealing element can fit against the inner wall of the molten plastic flow channel L to improve the sealing reliability when the flow channel is closed. It is configured such that: in the pre-plasticizing stage, the drive source drives the sealing element to open the molten plastic flow channel L so that the molten plastic can flow from the pre-plasticizing cylinder 4a into the injection cylinder 2a; in the injection stage, the drive source drives the sealing element to close the molten plastic flow channel L to prevent the molten plastic from flowing back towards the pre-plasticizing cylinder 4a. The following describes three different embodiments in detail with reference to the accompanying drawings.

[0048] Example 1

[0049] Example 1: V-type injection unit for injection molding machines based on an electric direct drive system. (See details below.) Figures 1 to 4 and Figure 14 As shown, the structure and connection relationship of the main components of the V-type injection unit of the injection molding machine in Example 1 are as follows:

[0050] Base 1: As the basic support structure of the entire device, it is equipped with a slidingly connected component linear guide rail 1a and slider 1b. The guide rail 1a is installed on the base 1 along the fixed surface of the injection molding machine. The slider 1b cooperates with the guide rail 1a. The injection barrel motor seat 2 is fixed to the slider 1b by screws or other means, thereby providing sliding guidance for the injection barrel motor seat 2 along the injection direction.

[0051] Injection barrel motor base 2: as shown Figures 1 to 4 and Figure 14 The injection cylinder motor seat 2 is slidably mounted on the linear guide rail 1a of the base 1 via four sliders 1b. The front end of the injection cylinder motor seat 2 is used to mount the injection cylinder 2a. The injection cylinder 2a contains an axially movable injection plunger 2b. Two guide rods 2i are symmetrically fixed on the outer side of the front part of the injection cylinder motor seat 2. The inner cavity of the front part of the injection cylinder motor seat 2 contains a bearing seat 2c. The bearing seat 2c has guide holes on both sides. The guide holes of the bearing seat 2c cooperate with the guide rods 2i, allowing the bearing seat to move freely in the inner cavity of the front part of the injection cylinder motor seat 2. The front end of the bearing seat 2c is connected to the rear part of the injection plunger. The bearing seat 2c contains... There is a bearing 2d, the inner hole of which is connected to the front end of the injection spline screw 2e. The rear spline shaft of the injection spline screw 2e meshes with the spline sleeve 2k in the direct drive injection motor 2j. The direct drive injection motor 2j is installed in the rear inner cavity of the injection barrel motor seat 2. The load sensor 2h is installed and fixed in the middle inner cavity of the injection barrel motor seat 2. The front end of the load sensor 2h is fixed with a screw mounting seat 2g. The two sides of the screw mounting seat 2g are equipped with anti-torque cam driven bearings (not shown in the figure). The fourth screw nut 2f is fixed on the screw mounting seat 2g and meshes with the screw part of the injection spline screw.

[0052] Slanted slider 3: It is fixed to the upper rear part of the injection cylinder motor base 2 by bolts and screws.

[0053] The pre-plastic cylinder motor base 4 is fixed to the inclined surface of the inclined slider 3 by pressure plate screws. A pre-plastic cylinder 4a is installed and fixed at the front end of the pre-plastic cylinder motor base 4. A rotatable screw 4b is inside the pre-plastic cylinder 4a. A direct-drive pre-plastic motor 4c is fixed in the rear inner cavity of the pre-plastic cylinder motor base 4. The output shaft of the direct-drive pre-plastic motor 4c is fixedly connected to the rear end of the pre-plastic screw 4b. A pre-plastic cylinder front body 4d is installed at the front end of the pre-plastic cylinder 4a and is connected in series in the molten plastic flow channel L. A pre-plastic connector 4e is connected in series between the pre-plastic cylinder front body 4d and the three-way connector 6. One end of the pre-plastic connector 4e is sealed to the pre-plastic cylinder front body 4d, and the other end is sealed to the three-way connector 6 to form a continuous flow channel from the pre-plastic cylinder 4a to the three-way connector 6. A first electric anti-reverse device 5a is fixedly installed in the inner cavity and outside of the pre-plastic cylinder front body 4d.

[0054] First electric anti-reverse device 5a: such as Figure 4 As shown, the first check valve core 5a1 is a sealing component of the electric check mechanism. It is axially movable and installed at the center of the pre-plastic cylinder front body 4d. Its contact area with the molten plastic flow channel L has a conical sealing surface. This conical sealing surface can fit against the inner wall of the flow channel within the pre-plastic cylinder front body 4d to improve the sealing reliability when the flow channel is closed. The first check valve rod 5a2 can drive the first check valve core 5a1 to move back and forth, keeping the first check valve core 5a1 in an open and closed state. The bracket 5a10 of the first electric check device 5a is installed outside the pre-plastic cylinder front body 4d. The swing bracket 5a9 is mounted on the fixed bracket 5a10 via a pin. The first sliding sleeve assembly 5a3 can slide on the central axis of the swing bracket 5a9 via a bushing and a key. The front end of the first sliding sleeve assembly 5a3 is connected to the outer end of the first check valve stem 5a2, and the rear end of the first sliding sleeve assembly 5a3 is connected to the first lead screw nut 5a4. The bearing seat 5a7 is installed at the other end of the swing bracket 5a9. The first lead screw 5a5 is connected to the bearing seat 5a7 and meshes with the first lead screw nut 5a4. The bearing seat cover 5a6 is fixed at the other end of the bearing seat 5a7. The first motor transmission assembly 5a8 is installed on the bearing seat cover 5a6 as a drive source. Its output shaft is engaged with the inner hole at the tail of the first lead screw 5a5. Through the rotation of the first motor transmission assembly 5a8, the first sliding sleeve assembly 5a3 slides back and forth, driving the first check valve stem 5a2 to swing, thereby realizing the opening and closing of the first check valve core 5a1.

[0055] T-connector 6: The rear end of the t-connector 6 is connected and fixed to the front end of the injection barrel 2a. The front end of the t-connector 6 is connected to the injection melt 6a. The front end of the injection melt 6a is equipped with an injection nozzle 6b. The upper end of the t-connector 6 is connected to the other end of the pre-plasticized connector 4e.

[0056] The overall electric moving assembly 7: The bottom of the overall electric assembly 7 is fixed to the front template of the injection molding machine's mold clamping component. The overall lead screw fixing seat 7c is fixed to the lower part of the injection cylinder motor seat 2 by screws. The overall lead screw nut 7b is connected to the overall lead screw fixing seat 7c by screws and springs. The overall lead screw 7q meshes with the overall lead screw nut 7b. The bearing 7d is installed at the front of the overall electric assembly 7. The tail of the overall lead screw 7q is connected to the inner hole of the bearing 7d. The overall motor is fixed in the inner cavity of the overall electric assembly seat 7. The output shaft of the overall motor drive 7j is connected to the inner hole of the tail of the overall lead screw 7q and fixed together. When the overall motor drive 7j rotates, it drives the overall lead screw 7q to rotate, thereby driving the injection cylinder motor seat 2 and the inclined slider 3, pre-plastic cylinder motor seat 4, the first electric anti-reverse device 5a, and the three-way connector 6 connected to the injection cylinder motor seat 2 to move together on the linear guide rail 1b.

[0057] In Example 1, the injection spline screw 2e, the fourth screw nut 2f, the screw mounting base 2g, and the direct-drive injection motor 2j can be arranged in multiple parallel configurations. In this parallel configuration, the load sensor 2h can be mounted at the front end of the bearing housing 2c.

[0058] The working process of the injection unit of the injection molding machine in Example 1 is as follows:

[0059] Pre-plasticizing state: When the injection molding machine is in the pre-plasticizing state, the first motor transmission component 5a8 in the first electric check device 5a is started, driving the first lead screw 5a5 to rotate, causing the first sliding sleeve component 5a3 to move, driving the first check valve rod 5a2 to swing, so that the first check valve core 5a1 is in the open state. At the same time, the direct drive pre-plasticizing motor 4c is started, driving the screw to rotate, and the pre-plasticized molten plastic enters the injection barrel 2a through the first check valve core 5a1, the pre-plasticizing connector 4e, and the three-way connector 6. The load sensor detects the set pressure and controls the direct drive injection motor 2j to rotate, driving the injection plunger 2b to move backward, thus completing the pre-plasticizing process. The injection barrel is filled with molten plastic to the set value, and the pre-plasticizing process ends.

[0060] Injection State: When the injection molding machine enters the injection state, the control system starts to enter the injection state after receiving the overall position signal. First, the first motor transmission component 5a8 in the first electric check valve 5a starts, which is exactly opposite to the starting direction in the pre-plasticizing state, so that the first check valve core 5a1 is in the closed position. Its conical sealing surface is tightly attached to the inner wall of the flow channel, improving the sealing reliability. After receiving the information that the first check valve core 5a1 is closed, the control system immediately starts the direct drive injection motor 2j to rotate (opposite to the pre-plasticizing state), driving the injection plunger 2b to inject the plasticized molten plastic into the mold cavity. During the injection process, there will be no backflow of molten plastic, which can achieve more precise and rapid injection.

[0061] Example 2

[0062] Example 2: V-type injection unit for injection molding machines based on an electric direct drive system, see details below. Figures 5 to 7 and Figure 15 In Example 2, the V-type injection device of the injection molding machine is identical in overall structure except for the pre-plastic cylinder motor base 4 and the second electric anti-reverse device 5b. Therefore, the connection relationship between the pre-plastic cylinder motor base 4 and the second electric anti-reverse device 5b in Example 2 is as follows:

[0063] The pre-plastic cylinder motor base 4 is fixed to the inclined surface of the inclined slider 3 by pressure plate screws. The front end of the pre-plastic cylinder motor base 4 is fixedly mounted with a pre-plastic cylinder 4a. The pre-plastic cylinder 4a contains a rotatable screw 4b. The rear inner cavity of the pre-plastic cylinder motor base 4 is fixedly mounted with a direct drive pre-plastic motor 4c. The output shaft of the direct drive pre-plastic motor 4c is fixedly connected to the rear end of the pre-plastic screw 4b. The front end of the pre-plastic cylinder 4a is connected to a first pre-plastic anti-reverse connector 5b2 connected in series in the molten plastic flow channel L. One end of the first pre-plastic anti-reverse connector 5b2 is connected to the front end of the pre-plastic cylinder 4a, and the other end is connected to a three-way connector 6 in the flow channel structure to form a continuous flow channel from the pre-plastic cylinder 4a to the three-way connector 6. The lower part of the first pre-plastic anti-reverse connector 5b2 is connected and fixed to the upper part of the three-way connector 6.

[0064] Second electric anti-reverse device 5b: such as Figure 7 , Figure 17 As shown, the bearing housing 5b4 is connected and fixed above the first pre-plasticized check valve 5b2, the bearing housing cover 5b5 is fixed above the bearing housing 5b4, the second motor drive device 5b6 is installed above the bearing housing cover 5b5 as a drive source, the second lead screw 5b3 is installed at the center of the bearing housing, the upper inner hole of the second lead screw 5b3 cooperates with the output shaft of the second motor drive device 5b6 to transmit torque, and the second check valve core 5b1 is provided as a sealing element in the first pre-plasticized check valve 5b2. The contact part of the second lead screw core 5b1 with the molten plastic flow channel L is provided with an annular sealing platform. The annular sealing platform can fit against the inner wall of the flow channel in the first pre-plasticized check valve 5b2 to improve the sealing reliability when the flow channel is closed. The lower thread of the second lead screw 5b3 cooperates with the upper threaded hole of the second check valve core 5b1, so that the second check valve core 5b1 can move up and down to realize the opening and closing of the check valve device.

[0065] The working process of the injection unit of the injection molding machine in Example 2 is as follows:

[0066] Pre-plasticizing state: When the injection molding machine is in the pre-plasticizing state, the second motor drive device 5b6 in the second electric check device 5b is started first, driving the second lead screw 5b3 to rotate, causing the second check valve core 5b1 to move upward and the second check valve core 5b1 to be in the open state. At the same time, the direct drive pre-plasticizing motor 4c is started, driving the screw to rotate, and the pre-plasticized molten plastic enters the injection barrel 2a through the second check valve core 5b1 and the three-way connector 6. After the load sensor detects the set pressure, it controls the direct drive injection motor 2j to rotate, driving the injection plunger 2b to move backward. The injection barrel 2a is filled with molten plastic to the set value, and the pre-plasticizing ends.

[0067] Injection State: When the injection molding machine enters the injection state, the control system, after receiving the overall position signal, begins the injection process. First, the second motor drive device 5b6 in the second electric check valve 5b starts, with its direction of rotation opposite to that during the pre-plasticizing state. This causes the second check valve core 5b1 to move downwards, closing the valve. Its annular sealing platform fits tightly against the inner wall of the flow channel, improving sealing reliability. Simultaneously, upon receiving the information that the second check valve core 5b1 is closed, the control system immediately starts the direct-drive injection motor 2j to rotate (opposite to the direction of rotation during pre-plasticizing). Through components such as the injection spline screw 2e, the injection plunger 2b is driven forward to inject the plasticized molten plastic into the mold cavity. Because the second check valve core 5b1 is closed, there is no backflow of molten plastic during injection, achieving more precise and rapid injection.

[0068] Through the structure of the second check valve core 5b1 Figure 17 The schematic diagram shows that the second check valve core 5b1 is a flow channel type valve core. Its outer circumferential surface is provided with an annular sealing inclined surface 5b11 set at an angle to the valve core axis. A first through inclined hole 5b12 set at an inclination to the axis is opened at the front of the annular inclined surface 5b11 to prevent molten plastic from stagnating and to clear the flow channel during the injection cycle.

[0069] Example 3

[0070] Example 3: V-type injection unit for injection molding machines based on an electric direct drive system, see details below. Figures 8 to 11 and Figure 16 In Example 3, the V-type injection device of the injection molding machine is identical in overall structure except for the pre-plastic cylinder motor base 4 and the third electric anti-reverse device 5c. Therefore, the connection relationship between the pre-plastic cylinder motor base 4 and the third electric anti-reverse device 5c in Example 3 is as follows:

[0071] The pre-plastic cylinder motor base 4 is fixed to the inclined surface of the inclined slider 3 by pressure plate screws. A pre-plastic cylinder 4a is installed and fixed at the front end of the pre-plastic cylinder motor base 4. A rotatable screw 4b is inside the pre-plastic cylinder 4a. A third electric anti-reverse device 5c is installed on the side and the middle inner cavity of the pre-plastic cylinder motor base 4. Figure 11 As shown, a linear pre-plasticizing motor 4c is fixed in the rear inner cavity of the pre-plasticizing cylinder motor base 4. The front end of the pre-plasticizing cylinder 4a is connected to a second pre-plasticizing anti-reverse connector 4f connected in series in the molten plastic flow channel L. One end of the second pre-plasticizing anti-reverse connector 4f is sealed to the front end of the pre-plasticizing cylinder 4a, and the other end is sealed to the three-way connector 6, forming a continuous flow channel from the pre-plasticizing cylinder 4a to the three-way connector 6. The lower part of the second pre-plasticizing anti-reverse connector 4f is connected and fixed to the upper part of the three-way connector 6.

[0072] Within the inner hole of the third sliding sleeve 5c3, the rotating shaft 5c5 can rotate relative to the third sliding sleeve 5c3 and move linearly along the axis of the screw 4b together with the third sliding sleeve 5c3. The inner hole at the front end of the rotating shaft 5c5 mates with the tail end of the screw 4b and is fixedly connected by a flat key, so that the screw 4b and the rotating shaft 5c5 form an integral unit and can rotate and move axially together. The tail end of the rotating shaft 5c5 mates with the inner hole of the output shaft of the linear pre-plasticizing motor 4c and is connected by a flat key, so that the tail end of the rotating shaft 5c5 can move linearly relative to the inner hole of the output shaft of the linear pre-plasticizing motor 4c. Pushing the rocker arm 5c2 can drive the third sliding sleeve 5c3, the rotating shaft 5c5, and the screw 4b to move linearly along the axis of the screw 4b, thereby realizing the closing and opening of the front end of the screw 4b and the second pre-plasticizing anti-reverse connector 4f.

[0073] Third electric anti-reverse device 5c: such as Figure 11 As shown, the rocker arm seat 5c1 is fixed to the side of the pre-plastic cylinder motor seat 4. A check valve locking bracket 5c6 with a check valve device is also fixed to the same side. The swing bracket 5c14 is mounted on the check valve locking bracket 5c6 via a pin. The bearing seat 5c7 is mounted and fixed to the swing bracket 5c14. The bearing seat cover is fixed to the top of the bearing seat 5c7. The third motor transmission assembly 5c12, as the drive source, is mounted and fixed on the bearing seat cover. The third lead screw 5c10 is installed in the middle of the bearing seat 5c7. The inner hole at the tail of the third lead screw 5c10 mates with the output shaft of the third motor transmission assembly 5c12, transmitting torque via a key connection. The second sliding sleeve assembly 5c8 is mounted on the swing bracket 5c14 via a bushing and a key, and can move back and forth along the shaft on the swing bracket 5c14. The front end of the second sliding sleeve assembly 5c8 is connected to the outer end of the rocker arm 5c2, and the rear end of the second sliding sleeve assembly 5c8... The screw 4b is equipped with a third lead screw nut 5c9, which meshes with the third lead screw 5c10. The midpoint of the rocker arm 5c2 is mounted on the fulcrum of the rocker arm seat 5c1 via a pin. The inner end of the rocker arm 5c2 is connected to the outside of the third sliding sleeve 5c3, allowing the third sliding sleeve 5c3 to move back and forth on the axis of the screw 4b via the rocker arm 5c2. The third sliding sleeve 5c3 is connected to the sleeve seat 5c13 via a flat key. The sleeve seat 5c13 is fixed in the middle inner cavity of the pre-plastic cylinder motor seat 4. The rotating shaft 5c5 is installed in the inner hole of the third sliding sleeve 5c3 via the bearing 5c4 and the center position of the third sliding sleeve 5c3. The front end of the screw 4b is a sealing component of the electric anti-reverse mechanism. Its contact part with the molten plastic flow channel L is provided with a conical sealing surface. This conical sealing surface can fit against the inner wall of the flow channel of the second pre-plastic anti-reverse connector 4f to improve the sealing reliability when the flow channel is closed.

[0074] The working process of the injection unit of the injection molding machine in Example 3 is as follows:

[0075] Pre-plasticizing state: When the injection molding machine is in the pre-plasticizing state, the third motor transmission component 5c12 in the third electric anti-reverse device 5c is started first, driving the third lead screw 5c10 to rotate, which drives the second sliding sleeve component 5c8 to move linearly, thereby driving the rocker arm 5c2 to swing, and then driving the third sliding sleeve 5c3, the rotating shaft 5c5, and the screw 4b to move backward together. The third electric anti-reverse device 5c is in the open state. At the same time, the direct drive pre-plasticizing motor 4c is started, driving the screw to rotate, and the pre-plasticized molten plastic enters the injection barrel 2a through the second pre-plasticizing anti-reverse connector 4f and the three-way connector 6. At this time, after the load sensor detects the set pressure, it controls the direct drive injection motor 2j to rotate, driving the injection plunger 2b to move backward. When the injection barrel 2a is filled with molten plastic to the set position, the pre-plasticizing ends.

[0076] Injection State: When the injection molding machine enters the injection state, the control system receives the overall position signal and begins the injection process. First, the third motor drive assembly 5c12 in the third electric anti-reverse device 5c starts, its direction of rotation being exactly opposite to that during the pre-plasticizing state. Through the third lead screw 5c10, the third lead screw nut 5c9, and the second sliding sleeve assembly 5c8, it pushes the rocker arm 5c2 backward, thereby driving the third sliding sleeve 5c3, the rotating shaft 5c5, and the screw 4b forward. The tapered sealing surface at the front end of the screw 4b contacts the second pre-plasticizing... The inner wall of the flow channel of the check valve 4f fits tightly, improving the sealing reliability. The axial force generated is greater than the backflow pressure of the molten plastic in the flow channel of the second pre-plasticized check valve 4f, achieving zero backflow. When the control system receives the check valve closing information, it immediately starts the direct drive injection motor 2j to rotate (in the opposite direction to that during pre-plasticization). Through the injection spline screw 2e and other components, it drives the injection plunger 2b to inject forward, injecting the plasticized molten plastic into the mold cavity. No backflow of molten plastic occurs during the injection process, achieving more precise and rapid injection.

[0077] It is necessary to further explain here: In embodiments 1, 2, and 3 above, preventing material accumulation in the injection plunger 2b is a crucial aspect of the injection molding machine. This invention addresses this by providing an inclined annular stepped surface 2b1 on the outer periphery of the injection plunger 2b. The front of this annular stepped surface 2b1 has a second through-hole 2b2 forming an angle with the axis of the injection plunger 2b. Two axially extending flow channels 2b3 of different widths are also provided on the outer periphery of the injection plunger 2b in front of the second through-hole 2b2. This allows a small amount of molten plastic remaining from the previous injection to be squeezed to the very front of the injection barrel during each pre-plasticizing process, thereby preventing material accumulation. See details... Figure 12 , Figure 13 The diagram shows the direction of molten plastic movement when pre-plasticizing begins. The direction indicated by the arrows allows the remaining molten plastic from the previous injection to be squeezed out to the front of the barrel, preventing the molten plastic from remaining in one place for an extended period.

[0078] It should be noted that in the description of this embodiment, the terms "front," "rear," "inner," "outer," "upper," and "lower," etc., indicating orientation or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are merely simplified descriptions for ease of describing the present invention and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can be directly connected or indirectly connected through an intermediate link; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

Claims

1. An injection unit for an injection molding machine, comprising: An injection unit having an injection barrel (2a) and an injection plunger (2b) axially movable within the injection barrel (2a); A pre-plasticizing unit having a pre-plasticizing cylinder (4a) and a screw (4b) rotatably disposed within the pre-plasticizing cylinder (4a); The flow channel structure includes a three-way connector (6), which is sealed to the front end of the injection barrel (2a) and the front end of the pre-plastic barrel (4a) to form a molten plastic flow channel (L) that can connect the pre-plastic barrel (4a) and the injection barrel (2a). Its features are: It also includes an electric anti-reverse mechanism, which includes a drive source and a sealing element driven by the drive source and movably disposed in the molten plastic flow channel (L); The electric anti-reverse mechanism is configured such that, during the pre-plasticizing stage, the drive source drives the sealing element to open the molten plastic flow channel (L) so that molten plastic can flow from the pre-plasticizing cylinder (4a) into the injection cylinder (2a); During the injection phase, the drive source drives the sealing element to close the molten plastic flow channel (L) to prevent the molten plastic from flowing back towards the pre-plasticized cylinder (4a).

2. The injection device of the injection molding machine according to claim 1, characterized in that: The sealing part of the electric anti-reverse mechanism has a sealing fit structure at the contact part with the molten plastic flow channel (L). The sealing fit structure includes a conical sealing surface or an annular sealing platform, and the sealing surface of the sealing part can fit against the inner wall of the molten plastic flow channel (L) to improve the sealing reliability when the flow channel is closed.

3. The injection device of the injection molding machine according to claim 1, characterized in that: The electric anti-reverse mechanism is a first electric anti-reverse device (5a), which is installed in series in the molten plastic flow channel (L) and connected to the front end of the pre-plastic cylinder (4a) on the pre-plastic cylinder front body (4d). A pre-plasticized connector (4e) is connected in series between the pre-plasticized cylinder front body (4d) and the tee connector (6). One end of the pre-plasticized connector (4e) is sealed to the pre-plasticized cylinder front body (4d), and the other end is sealed to the tee connector (6) to form a continuous flow channel from the pre-plasticized cylinder (4a) to the tee connector (6). The sealing element is a first check valve core (5a1), which is axially movable and disposed within the pre-plastic cylinder front body (4d); The driving source is a first motor transmission assembly (5a8), which drives the first check valve stem (5a2) to swing through a transmission mechanism, thereby causing the first check valve core (5a1) to move axially between the open and closed positions.

4. The injection device of the injection molding machine according to claim 3, characterized in that: The transmission mechanism of the first electric anti-reverse device (5a) includes a first lead screw (5a5), a first lead screw nut (5a4) meshing with the first lead screw (5a5), and a first sliding sleeve assembly (5a3) connected to the first lead screw nut (5a4); The first motor transmission assembly (5a8) drives the first lead screw (5a5) to rotate. The outer end of the first check valve rod (5a2) is connected to the front end of the first sliding sleeve assembly (5a3). The linear motion of the first sliding sleeve assembly (5a3) drives the first check valve rod (5a2) to swing, thereby driving the first check valve core (5a1) to move axially.

5. The injection device of the injection molding machine according to claim 1, characterized in that: The electric anti-reverse mechanism is a second electric anti-reverse device (5b), which is installed on the first pre-plastic anti-reverse connector (5b2) connected in series in the molten plastic flow channel (L). One end of the first pre-plastic anti-reverse connector (5b2) is connected to the front end of the pre-plastic cylinder (4a), and the other end is connected to the three-way connector (6) in the flow channel structure to form a continuous flow channel from the pre-plastic cylinder (4a) to the three-way connector (6). The sealing component is a second check valve core (5b1), which is located inside the first pre-molded check valve body (5b2); The driving source is a second motor transmission device (5b6), which drives the second lead screw (5b3) to rotate. The second lead screw (5b3) cooperates with the screw hole provided on the second check valve core (5b1) to drive the second check valve core (5b1) to move up and down to realize the opening and closing of the flow channel.

6. The injection device of the injection molding machine according to claim 5, characterized in that: The second check valve core (5b1) is a flow channel type valve core. Its outer circumferential surface is provided with an annular sealing slope (5b11) set at an angle to the axis, and a first through inclined hole (5b12) set at an angle to the axis is opened at the front of the annular slope (5b11) to prevent molten plastic from stagnating and to clear the flow channel during the injection cycle.

7. The injection device of the injection molding machine according to claim 1, characterized in that: The electric anti-reverse mechanism is a third electric anti-reverse device (5c), which is installed on the side and the middle inner cavity of the pre-plastic cylinder motor seat (4); The flow channel structure is connected in series with a second pre-plastic anti-reverse connector (4f). One end of the second pre-plastic anti-reverse connector (4f) is sealed to the front end of the pre-plastic cylinder (4a), and the other end is sealed to the tee connector (6), forming a continuous flow channel from the pre-plastic cylinder (4a) to the tee connector (6). The sealing component is the front end of the pre-plasticized screw (4b); The driving source is a third motor transmission assembly (5c12). The third motor transmission assembly (5c12) drives the pre-plasticized screw (4b) to move along the axis through the transmission mechanism. When the pre-plasticized screw (4b) moves to the position, the front end of the pre-plasticized screw (4b) is in close contact with the flow channel end face of the second pre-plasticized anti-reverse connector (4f) to close the molten plastic flow channel (L). When the pre-plasticized screw (4b) retracts, the flow channel is opened.

8. The injection device of the injection molding machine according to claim 7, characterized in that: The transmission mechanism of the third electric anti-reverse device (5c) includes a third lead screw (5c10), a third lead screw nut (5c9) meshing with the third lead screw (5c10), a second sliding sleeve assembly (5c8) connected to the third lead screw nut (5c9), and a rocker arm (5c2). The third motor transmission assembly (5c12) drives the third lead screw (5c10) to rotate. One end of the rocker arm (5c2) is connected to the second sliding sleeve assembly (5c8), and the other end is connected to the third sliding sleeve (5c3) sleeved outside the screw (4b). The linear motion of the second sliding sleeve assembly (5c8) drives the rocker arm (5c2) to swing, thereby driving the third sliding sleeve (5c3) and the screw (4b) connected thereto to move along the axis.

9. The injection device of the injection molding machine according to any one of claims 1 to 8, characterized in that: The outer periphery of the injection plunger (2b) is provided with an inclined annular stepped surface (2b1). The front part of the annular stepped surface has a second through inclined hole (2b2) ​​that forms an angle with the axis of the injection plunger (2b). On the outer periphery of the injection plunger (2b) in front of the second through inclined hole (2b2), there are also two flow channel grooves (2b3) that extend axially and have different widths.

10. The injection device of the injection molding machine according to any one of claims 1 to 8, characterized in that: The injection unit also includes an injection drive system for driving the injection plunger (2b). The injection drive system is an electric drive system, which includes at least one set of direct-drive injection motors (2j), a spline screw (2e) connected to the output end of the direct-drive injection motor (2j) via a spline, and a fourth screw nut (2f) meshing with the screw portion of the spline screw (2e).

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