Injection device of electric pre-molding single-cylinder hydraulic injection molding machine

Abstract

An injection device of an electric pre-molding single-cylinder hydraulic injection molding machine comprises a first base, a second base arranged on the first base, a direct-drive pre-molding motor arranged on the second base, a bearing seat assembly and an injection molding oil cylinder assembly. A rotor of a direct-drive pre-molding motor is connected with a spline sleeve and forms an axial sliding spline pair with an output shaft, meanwhile, the front end of the output shaft is fixedly connected with the tail of a screw rod, and in addition, a bearing seat assembly is arranged at the rear end of the output shaft and is driven by an injection molding oil cylinder assembly to move in the axial direction. Due to the adoption of a transmission mode of combining the direct-drive motor and the hydraulic oil cylinder, not only is the decoupling of rotary pre-molding and axial injection molding motion of the screw realized, but also the high efficiency and stability of the injection molding process are ensured, and meanwhile, the linear guide mechanism restrains the bearing seat assembly to only move axially, so that the influence of rotary motion on the injection molding precision is effectively avoided, and the production efficiency is improved. And the injection molding quality and the production efficiency are obviously improved.

Description

Technical Field

[0001] The invention relates to the field of injection molding machines, in particular to an injection device of a dynamic pre-molding single-cylinder hydraulic injection molding machine. Background Art

[0002] With the increasing application of injection molding technology across various industrial sectors, performance requirements for the injection units of electric pre-molding single-cylinder hydraulic injection molding machines continue to increase. Current single-cylinder hydraulic injection molding machines typically utilize independent drive mechanisms to control the screw's rotation and axial movement, respectively, to achieve both pre-molding and injection functions. However, this design has exposed defects in actual operation that significantly impact equipment reliability and production efficiency. In some systems, the mechanical linkage between the screw's rotation drive and the axial movement drive mechanism forces the injection piston rod to rotate synchronously with the screw during operation.

[0003] For example, the Chinese utility model patent application number 201320429419.X (authorization publication number CN203391246U) discloses a single-cylinder injection mechanism, in which the drive shaft is connected to the sleeve piston via a thrust self-aligning ball bearing. While this theoretically isolates rotational motion, the lack of a rigid rotation constraint means that in practice, when bearings wear or loads fluctuate, the piston rod may still passively rotate slightly. This rotation forces the seal to withstand a combined load, shortening the seal failure period. It also exacerbates wear between the rolling bearing and the drive shaft, causing fluctuations in the screw-barrel clearance and significantly increasing the scrap rate of finished products.

[0004] Furthermore, existing technologies rely on purely hydraulic drive systems, resulting in low energy conversion efficiency. The synchronization of rotation and axial motion is highly dependent on hydraulic control, making it susceptible to oil pressure fluctuations and difficult to meet the production requirements of high-precision injection molding. Although some technologies attempt to prevent piston rod rotation by decoupling the drive chain, these technologies are complex and energy consumption issues remain unresolved. The core pain point remains the failure of seals, component wear, and precision degradation caused by rotation.

[0005] Therefore, there is an urgent need for an innovative solution that can completely eliminate piston rod rotation, optimize drive energy efficiency and simplify the structure to break through the existing technical bottleneck. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an injection device for an electric pre-molding single-cylinder hydraulic injection molding machine that is decoupled from the screw rotation drive and axial movement drive, combined with a hybrid drive mode of motor direct-drive pre-molding and hydraulic injection molding, and completely eliminates the rotation of the piston rod to achieve efficient drive and simplified structure.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: the injection device of the electric pre-molding single-cylinder hydraulic injection molding machine includes

[0008] First base;

[0009] The second base is arranged on the first base, and a barrel is installed at the front end thereof, and a screw capable of rotating and axially moving is arranged in the barrel;

[0010] A direct-drive pre-plasticizing motor is mounted on the second base, and its rotor is connected to a spline sleeve. The spline sleeve is connected to the output shaft via an axially sliding spline pair, so that a transmission structure is formed between the output shaft and the spline sleeve that rotates synchronously and allows axial relative sliding. The output shaft is connected to the screw. A brake is also formed inside the direct-drive pre-plasticizing motor to lock the rotation of the output shaft.

[0011] A bearing seat assembly is provided on the output shaft and supports the output shaft through a bearing;

[0012] An injection cylinder assembly is provided at the rear end of the second base, with its piston rod extending forward and fixedly connected to the bearing seat assembly; and

[0013] A linear guide mechanism is provided between the bearing seat assembly and the second base, and is used to constrain the bearing seat assembly and the piston rod to move only in an axial linear direction;

[0014] In the pre-plasticization state, the direct-drive pre-plasticization motor drives the output shaft and the screw to rotate to achieve pre-plasticization, and the brake is in a released state at this time;

[0015] In the injection state, the injection cylinder assembly drives the piston rod to advance axially, and drives the output shaft and the screw to move forward through the bearing seat assembly to achieve injection molding. At this time, the brake is in a locked state;

[0016] Wherein, the piston rod and the output shaft are rotationally decoupled via the linear guide mechanism and the axial sliding spline pair.

[0017] In order to optimize the installation structure of the injection cylinder assembly and the linear guide mechanism, preferably, a cylinder mounting seat is also included, the cylinder mounting seat is arranged at the rear end of the second base, the injection cylinder assembly is arranged at the rear end of the cylinder mounting seat, and the linear guide mechanism is arranged between the bearing seat assembly and the cylinder mounting seat.

[0018] In order to enhance the stability of the linear guide and provide a variety of optional solutions to meet the requirements of different working conditions, preferably, the linear guide mechanism includes a guide ring provided on the cylinder mounting seat and a roller provided on the bearing seat assembly, and the roller is embedded in the axial groove of the guide ring to limit the rotational freedom of the bearing seat assembly and the piston rod;

[0019] Alternatively, the linear guide mechanism is a first linear guide rail, and the bearing seat assembly is slidably connected to the first linear guide rail via a first slider to limit the rotational freedom of the bearing seat assembly and the piston rod;

[0020] Alternatively, the linear guide mechanism is a first linear guide rod, and the bearing seat assembly is slidably connected to the first linear guide rod through a first guide sleeve to limit the rotational freedom of the bearing seat assembly and the piston rod.

[0021] In order to improve the reliability of the rotational freedom restriction and reduce vibration and deflection during movement, preferably, the rollers are a pair of symmetrically arranged, and the guide ring is provided with a pair of axial grooves corresponding to the rollers. The two rollers are respectively embedded in the corresponding axial grooves to enhance the stability of the rotational freedom restriction of the bearing seat assembly and the piston rod.

[0022] In order to optimize the bearing support structure and improve the rotation accuracy and axial load-bearing capacity of the output shaft, preferably, the rear end of the output shaft is also connected to a core shaft, and the bearing is sleeved on the core shaft and rotatably connected to the bearing seat assembly.

[0023] In order to facilitate the installation and maintenance of the motor and the barrel and improve the modularity of the overall structure, preferably, the second base adopts a split structure, including

[0024] A barrel seat, the front end of which is fixed with the barrel;

[0025] The motor seat is detachably connected to the rear end of the barrel seat through a bolt group;

[0026] The direct-drive pre-plasticizing motor is integrally built into the motor base, and the oil cylinder mounting base is fixedly arranged at the rear end of the motor base.

[0027] In order to enhance the rigidity and assembly convenience of the bearing seat assembly and optimize the connection method between the roller and the piston rod, preferably, the bearing seat assembly includes a front-end bearing seat and a rear-end bearing seat, and the front-end bearing seat and the rear-end bearing seat are connected to each other and enclose a chamber for accommodating the core shaft and the bearing, the roller is arranged on the outer peripheral surface of the rear-end bearing seat, and the front end of the piston rod is fixedly connected to the rear-end bearing seat by fasteners.

[0028] In order to improve the sealing and movement smoothness of the cylinder and optimize the reliability of the hydraulic drive, preferably, the hydraulic cylinder assembly also includes a front cylinder cover, a cylinder body, a rear cylinder cover and a piston. The front cylinder cover is connected to the rear end of the cylinder mounting seat, the front end of the cylinder body is connected to the front cylinder cover, and the rear end is connected to the rear cylinder cover. The piston is slidably arranged in the cylinder body and cooperates with the piston rod.

[0029] In order to ensure the mutual connection between the second base and the injection molding equipment and to provide a variety of sliding guide solutions to adapt to different load requirements, preferably, the second base is slidably arranged on the first base along the injection direction, and a sliding connection structure is provided between the second base and the first base, and the sliding connection structure includes a linear guide rail assembly or a guide rod and guide sleeve assembly;

[0030] The linear guide rail assembly includes a second guide rail provided on the first base and a second slider fixedly connected to the second base;

[0031] The guide rod and guide sleeve assembly includes a second guide rod arranged on the first base and a second guide sleeve fixedly connected to the second base.

[0032] In order to optimize the matching accuracy of the spline transmission and ensure the reliability of synchronous rotation and axial sliding, preferably, axially extending spline teeth are distributed on the inner hole wall of the spline sleeve, and the outer peripheral surface of the output shaft is provided with a spline groove adapted to the spline teeth. Through the matching of the spline teeth and the spline groove, the output shaft and the spline sleeve can achieve synchronous rotation transmission and allow axial relative sliding between the two.

[0033] In order to improve the compactness and coaxiality of the overall structure and reduce assembly errors and motion interference, preferably, the second base is an integrated structure, the barrel is installed at the front end, the direct-drive pre-plasticization motor is built-in in the middle section, and the injection cylinder mounting seat is installed at the rear end. The axes of the barrel, direct-drive pre-plasticization motor and cylinder mounting seat coincide to form a coaxial integrated distribution.

[0034] In order to simplify the design of the guide mechanism and improve the movement stability of the bearing seat assembly, preferably, the linear guide mechanism includes a guide track extending axially on the inner wall of the cylinder mounting seat and a roller provided on the bearing seat assembly, and the roller is embedded in the guide track to limit the rotational freedom of the bearing seat assembly and the piston rod.

[0035] Compared with the existing technology, the advantages of the present invention are: the direct-drive pre-plasticizing motor rotor is directly connected to the screw through a coaxial direct-drive integrated design, and the direct-drive pre-plasticizing motor and the injection molding transmission system are arranged side by side on the same base body, thereby achieving deep coordination between the screw rotation plasticizing and the injection molding seat axial injection action; in response to the problems of long transmission chain and high energy loss in the existing technology, the design abandons the traditional multi-stage transmission components and shortens the transmission path with an extremely simple drive side-by-side linkage structure, solving the problems of response lag and uneven plasticizing caused by the accumulation of mechanical clearance, significantly improving transmission efficiency and reducing energy loss; at the same time, since pre-plasticizing and injection molding are integrated into the same base body and the drive system is integrated and linked, the horizontal space occupation is greatly reduced, the weight of the injection molding seat is significantly reduced, the motion inertia is reduced, the response speed is improved, and the problem of slow start-up and inability to adapt to high-speed injection molding of traditional devices is solved; in addition, by flexibly switching the pre-plasticizing backward and injection forward power, combined with the rigidity advantage of the direct-drive structure, the device can also stably adapt to injection molding needs of different scales, solving the problem that the existing technology is insufficiently adaptable to medium and large equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the three-dimensional structure of Example 1;

[0037] Figure 2 This is a side orthographic projection view of Example 1;

[0038] Figure 3 for Figure 2 AA cross-sectional structural diagram;

[0039] Figure 4 for Figure 2 BB cross-sectional structure diagram;

[0040] Figure 5 Schematic diagram of the structure of the guide ring in Example 1;

[0041] Figure 6 Schematic diagram of the three-dimensional structure of Example 2;

[0042] Figure 7 This is a side orthographic projection view of Example 2;

[0043] Figure 8 for Figure 7 Schematic diagram of CC cross-sectional structure;

[0044] Figure 9 for Figure 7 DD cross-sectional structure diagram;

[0045] Figure 10 Schematic diagram of the structure of the conductor track in Example 2;

[0046] Figure 11 Schematic diagram of another matching structure between the motor and the output shaft;

[0047] Figure 12 Schematic diagram of another matching structure between the motor and the output shaft;

[0048] Figure 13 This is another schematic diagram of the matching structure between the motor and the output shaft. DETAILED DESCRIPTION

[0049] The present invention will be further described in detail with reference to the accompanying drawings.

[0050] Figures 1 to 13 The figure shows two schematic diagrams of the present invention. The injection devices of the electric pre-molding single-cylinder hydraulic injection molding machine in Example 1 and Example 2 both include core components such as a first base 1, a second base 2, a direct-drive pre-molding motor 3, a bearing seat assembly 4, a cylinder mounting seat 5, an injection cylinder assembly 6, and a linear guide mechanism 7. The two embodiments are described in detail below in conjunction with the contents of the patent specification.

[0051] Example 1

[0052] Example 1 is based on the injection device of the split second base 2, for details, refer to Figures 1 to 5 As shown, the structure and connection relationship of its main components are as follows:

[0053] First base 1: The first base 1 is used as the basic supporting structure of the device, and a sliding connection structure 8 is provided on it. Figure 1 and Figure 2 As shown, the sliding connection structure 8 adopts a linear guide rail assembly, including a second guide rail 8a fixedly installed along the injection molding direction and a second slider 8b fixedly connected to the second base 2, providing a sliding guide for the second base 2 along the injection molding direction. Of course, the sliding connection structure 8 here can also adopt a guide rod and guide sleeve assembly, through a second guide rod provided on the first base 1 and a second guide sleeve fixedly connected to the second base 2.

[0054] Second base 2: Figures 1 to 3 As shown, the second base 2 is slidably mounted to the first base 1 via a second slider 8b. It adopts a split structure and includes a barrel base 21 and a motor base 22. The barrel base 21 has a barrel 2a fixedly mounted at its front end, and a screw 2b is disposed within the barrel 2a, which is rotatable and axially movable. The motor base 22 is detachably connected to the rear end of the barrel base 21 via a bolt assembly. It houses a direct-drive pre-plasticizing motor 3 and has a cylinder mounting base 5 fixed to its rear end.

[0055] Direct drive pre-plasticizing motor 3: Reference Figure 3 As shown, the rotor 3a of the direct-drive pre-molding motor 3 is connected to a splined sleeve 3d. The spline teeth 3d1 on the inner wall of the splined sleeve 3d and the spline grooves 3c1 on the outer periphery of the output shaft 3c form an axially sliding spline pair, achieving a transmission structure that combines synchronous rotation with axial relative sliding. The front end of the output shaft 3c is fixedly connected to the rear end of the screw 2b, and the rear end is connected to the core shaft 3e. The direct-drive pre-molding motor 3 also has a brake 3z internally formed to lock the output shaft 3c's rotation. When locked, the brake 3z only allows the output shaft 3c to move axially, preventing free rotation.

[0056] Bearing seat assembly 4: Located at the rear end of output shaft 3c, it supports output shaft 3c via bearing 4c. It comprises a front bearing seat 4a and a rear bearing seat 4b, which together form a chamber to accommodate core shaft 3e and bearing 4c. A roller 7b is provided on the outer circumference of rear bearing seat 4b and is fixedly connected to the front end of piston rod 6a.

[0057] Injection cylinder assembly 6: Located at the rear end of cylinder mounting base 5, injection cylinder assembly 6 comprises a front cylinder head 6b, cylinder body 6c, rear cylinder head 6d, and piston 6e. Piston rod 6a extends forward and is fixedly connected to the rear end bearing seat 4b of bearing seat assembly 4, achieving axial movement through hydraulic drive.

[0058] Linear guide mechanism 7: adopts the guide structure of "guide ring 7a + roller 7b", refer to Figures 3 to 5As shown, the guide ring 7a is fixed in the cylinder mounting seat 5, and the roller 7b provided on the outer periphery of the rear end bearing seat 4b is embedded in the axial groove 7a1 of the guide ring 7a, limiting the rotational freedom of the bearing seat assembly 4 and the piston rod 6a, ensuring that it only moves in an axial straight line. Here, the roller 7b and the axial groove 7a1 are each provided in pair and are symmetrically arranged to enhance the stability of limiting the rotational freedom of the bearing seat assembly 4 and the piston rod 6a.

[0059] Of course, the linear guide mechanism 7 here can also adopt the guiding form of "first linear guide rail + first slider" or "first linear guide rod + first guide sleeve" to achieve the same function through rigid guidance. The specific structure of this part is not shown in the drawings.

[0060] The working principle of the injection device of the electric pre-molding single-cylinder hydraulic injection molding machine in Example 1 is as follows:

[0061] Pre-plasticization stage: Direct-drive pre-plasticization motor 3 is energized, and rotor 3a rotates splined sleeve 3d, which in turn drives output shaft 3c and screw 2b through the spline pair. As screw 2b rotates, the plastic is sheared and plasticized within barrel 2a. The reaction force propels screw 2b, output shaft 3c, and mandrel 3e backward. Bearing support assembly 4 moves backward with mandrel 3e. Roller 7b on rear bearing support 4b slides axially within slot 7a1 in guide ring 7a, forcing piston rod 6a to retract into cylinder body 6c. The hydraulic system is now in a low-pressure follow-up state, and brake 3z is released.

[0062] During the injection molding phase, the hydraulic system injects high-pressure oil into cylinder 6c, pushing piston 6e and piston rod 6a forward. Piston rod 6a, via rear bearing 4b, propels core shaft 3e, output shaft 3c, and screw 2b axially forward. The direct-drive pre-molding motor 3 locks rotor 3a via the control unit. The splined pair between spline sleeve 3d and output shaft 3c allows axial movement of output shaft 3c but restricts rotation. Simultaneously, roller 7b slides linearly within axial groove 7a1 of guide ring 7a, ensuring that piston rod 6a and screw 2b move only axially. Brake 3z is now locked.

[0063] Example 2

[0064] Example 2 is an injection device based on the integral second base 2, specifically referring to Figures 6 to 10 As shown, the core structure thereof differs from that of Example 1 as follows:

[0065] The second base 2 is an integrated structure, with a barrel 2a installed at the front end, a direct-drive pre-plasticizing motor 3 built in the middle section, and an injection cylinder mounting seat 5 installed at the rear end. The axes of the barrel 2a, the direct-drive pre-plasticizing motor 3 and the cylinder mounting seat 5 coincide with each other, forming a coaxial integrated distribution to improve the rigidity of the system.

[0066] Linear guide mechanism 7: adopts the guide structure of "guide rail 7g + roller 7b", refer to Figures 8 to 10 As shown, the inner wall of the oil cylinder mounting seat 5 is provided with an axial guide track 7g, and the roller 7b of the bearing seat assembly 4 is embedded in the groove, which adapts to the inner wall layout of the integral structure and enhances the rotation constraint stability.

[0067] The working principle of the injection device of the electric pre-molding single-cylinder hydraulic injection molding machine in Example 2 is as follows:

[0068] Pre-plasticization stage: After the direct-drive pre-plasticization motor 3 is started, it drives the output shaft 3c to rotate through the built-in spline sleeve 3d, driving the screw 2b to rotate in the barrel 2a to plasticize the material. At the same time, the screw 2b pushes the bearing seat assembly 4 back along the guide track 7g. The roller 7b rolls in the guide track 7g to ensure the accuracy of linear motion. The core shaft 3e and bearing 4c provide stable support for the output shaft 3c.

[0069] Injection stage: The hydraulic system drives the piston 6e forward, pushing the rear-end bearing seat 4b through the piston rod 6a, driving the output shaft 3c and screw 2b forward to complete the injection. The double rollers 7b roll in the guide track 7g to effectively prevent rotational deviation. The integrated structure of the second base 2 ensures the coaxial movement of all components. The split bearing seat design ensures movement accuracy and facilitates maintenance.

[0070] In addition, in order to provide more solutions, the direct drive pre-plasticizing motor here can also adopt another layout, refer to Figures 11 to 13 As shown, by arranging the motor E in parallel with the output shaft 3c and adopting other transmission structures such as a gear set F or a transmission belt set, the power output end of the motor E is connected to the output shaft 3c to achieve a driving connection, thereby shortening the axial length to adapt to different injection molding application scenarios. Figures 11 to 13 The main difference between the three direct-drive pre-molded motor layouts is the installation position of the output shaft 3c and the spline sleeve 3d. Please refer to the attached figure for details.

[0071] It should be noted that in the description of this embodiment, the terms "front, back", "left, right", "inside, outside", "up, down", etc. indicating directions or positional relationships are all based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention. The terms "install", "connect", and "connected" should be understood in a broad sense. For example, they can be fixedly connected, detachably connected, or integrally connected; they can be directly connected, or indirectly connected through an intermediate medium, or they can be internal connections between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. An electric pre-molding single-cylinder hydraulic injection molding machine injection device, comprising a first base (1); The second base (2) is arranged on the first base (1), and a barrel (2a) is installed at its front end. A screw (2b) capable of rotating and axially moving is arranged in the barrel (2a); the characteristics are: Also includes A direct-drive pre-plasticizing motor (3) is provided on the second base (2), wherein a rotor (3a) thereof is connected to a spline sleeve (3d), wherein the spline sleeve (3d) is connected to an output shaft (3c) via an axially sliding spline pair, so that a transmission structure is formed between the output shaft (3c) and the spline sleeve (3d) that rotates synchronously and allows axial relative sliding. The output shaft (3c) is connected to a screw (2b), and a brake (3z) is also formed inside the direct-drive pre-plasticizing motor (3) for locking the rotation of the output shaft (3c); A bearing seat assembly (4) is provided on the output shaft (3c) and supports the output shaft (3c) via a bearing (4c); An injection cylinder assembly (6) is provided at the rear end of the second base (2), with a piston rod (6a) extending forward and fixedly connected to the bearing seat assembly (4); and A linear guide mechanism (7) is provided between the bearing seat assembly (4) and the second base (2) to constrain the bearing seat assembly (4) and the piston rod (6a) to move only in an axial linear direction; In the pre-plasticization state, the direct-drive pre-plasticization motor (3) drives the output shaft (3c) and the screw (2b) to rotate to achieve pre-plasticization, and at this time the brake (3z) is in a released state; In the injection molding state, the injection cylinder assembly (6) drives the piston rod (6a) to advance axially, and drives the output shaft (3c) and the screw (2b) to move forward through the bearing seat assembly (4) to achieve injection molding. At this time, the brake (3z) is in a locked state; The piston rod (6a) and the output shaft (3c) are rotationally decoupled via the linear guide mechanism (7) and the axial sliding spline pair.

2. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 1 is characterized in that: It also includes a cylinder mounting seat (5), the cylinder mounting seat (5) is arranged at the rear end of the second base (2), the injection cylinder assembly (6) is arranged at the rear end of the cylinder mounting seat (5), and the linear guide mechanism (7) is arranged between the bearing seat assembly (4) and the cylinder mounting seat (5).

3. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 2 is characterized in that: The linear guide mechanism (7) comprises a guide ring (7a) provided on the oil cylinder mounting seat (5) and a roller (7b) provided on the bearing seat assembly (4); the roller (7b) is engaged in an axial groove (7a1) of the guide ring (7a) to limit the rotational freedom of the bearing seat assembly (4) and the piston rod (6a); Alternatively, the linear guide mechanism (7) is a first linear guide rail, and the bearing seat assembly (4) is slidably connected to the first linear guide rail via a first slider to limit the rotational freedom of the bearing seat assembly (4) and the piston rod (6a); Alternatively, the linear guide mechanism (7) is a first linear guide rod, and the bearing seat assembly (4) is slidably connected to the first linear guide rod via a first guide sleeve to limit the rotational freedom of the bearing seat assembly (4) and the piston rod (6a).

4. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 3 is characterized in that: The rollers (7b) are a pair arranged symmetrically, and the guide ring (7a) is provided with a pair of axial slots (7a1) corresponding to the rollers (7b). The two rollers (7b) are respectively embedded in the corresponding axial slots (7a1) to enhance the stability of the rotational freedom restriction of the bearing seat assembly (4) and the piston rod (6a).

5. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 1 is characterized in that: The rear end of the output shaft (3c) is also connected to a core shaft (3e), and the bearing (4c) is sleeved on the core shaft (3e) and rotatably connected to the bearing seat assembly (4).

6. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to any one of claims 1 to 5, characterized in that: The second base (2) adopts a split structure, comprising a barrel seat (21), the front end of which is fixedly mounted with the barrel (2a); A motor seat (22) is detachably connected to the rear end of the barrel seat (21) via a bolt assembly; The direct-drive pre-plasticizing motor (3) is integrally built into the motor base (22), and the oil cylinder mounting base (5) is fixedly arranged at the rear end of the motor base (22).

7. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 5, characterized in that: The bearing seat assembly (4) includes a front-end bearing seat (4a) and a rear-end bearing seat (4b), wherein the front-end bearing seat (4a) and the rear-end bearing seat (4b) are connected to each other and enclose a chamber for accommodating the core shaft (3e) and the bearing (4c), the roller (7b) is arranged on the outer peripheral surface of the rear-end bearing seat (4b), and the front end of the piston rod (6a) is fixedly connected to the rear-end bearing seat (4b) by a fastener.

8. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 2, characterized in that: The hydraulic cylinder assembly (6) further comprises a front cylinder cover (6b), a cylinder body (6c), a rear cylinder cover (6d) and a piston (6e); the front cylinder cover (6b) is connected to the rear end of the cylinder mounting seat (5); the front end of the cylinder body (6c) is connected to the front cylinder cover (6b), and the rear end is connected to the rear cylinder cover (6d); the piston (6e) is slidably disposed in the cylinder body (6c) and is linked to the piston rod (6a).

9. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 1, characterized in that: The second base (2) is slidably arranged on the first base (1) along the injection direction, and a sliding connection structure (8) is provided between the second base (2) and the first base (1), and the sliding connection structure (8) includes a linear guide rail assembly or a guide rod and guide sleeve assembly; The linear guide rail assembly comprises a second guide rail (8a) provided on the first base (1) and a second slider (8b) fixedly connected to the second base (2); The guide rod and guide sleeve assembly comprises a second guide rod provided on the first base (1) and a second guide sleeve respectively fixedly connected to the second base (2).

10. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 1, characterized in that: Axially extending spline teeth are distributed on the inner hole wall of the spline sleeve (3d), and the outer peripheral surface of the output shaft (3c) is provided with spline grooves adapted to the spline teeth. The spline teeth cooperate with the spline grooves, so that the output shaft and the spline sleeve can achieve synchronous rotation transmission and allow axial relative sliding between the two.

11. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 1, characterized in that: The second base (2) is an integrated structure, with the barrel (2a) mounted on its front end, a direct-drive pre-molding motor (3) built into the middle section, and the injection cylinder mounting seat (5) mounted on the rear end. The axes of the barrel (2a), the direct-drive pre-molding motor (3) and the cylinder mounting seat (5) coincide with each other to form a coaxial integrated distribution.

12. The injection device of the electric pre-molding single-cylinder hydraulic injection molding machine according to claim 11, characterized in that: The linear guide mechanism (7) comprises a guide track (7g) provided on the inner wall of the oil cylinder mounting seat (5) and extending in the axial direction, and a roller (7b) provided on the bearing seat assembly (4); the roller (7b) is embedded in the guide track (7g) to limit the rotational freedom of the bearing seat assembly (4) and the piston rod (6a).

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