Hydraulic driving system of vertical injection molding machine and injection molding machine

Abstract

The utility model relates to the field of injection molding, in particular to a hydraulic driving system of a vertical injection molding machine and the injection molding machine. In the glue melting process, raw materials are in a molten and plasticized state, the screw is pushed to retreat along with continuous accumulation of the raw materials, namely, the screw moves upwards, at the moment, a coil YA1 of the glue injecting and melting control valve is powered on, a port P and a port B of the glue injecting and melting control valve are communicated, a port A and a port T of the glue injecting and melting control valve are communicated, and an auxiliary pump provides pressure oil which enters a rodless cavity of a glue injecting oil cylinder; the auxiliary pump provides constant pressure for a rodless cavity of the glue injecting and melting oil cylinder and is used for balancing influences caused by the weight of a motor and the weight of a tail plate, a rod cavity of the glue injecting oil cylinder is connected with the back pressure valve, and the back pressure valve and the auxiliary pump assembly are matched to enable the rodless cavity and the rod cavity of the glue injecting oil cylinder to be in a dynamic balance state. The back pressure valve more accurately controls the pressure of a rod cavity of the glue injection oil cylinder, and the influence caused by the pressure brought by a motor and the like is eliminated through the auxiliary pump.

Description

TECHNICAL FIELD

[0001] The utility model relates to injection molding field especially relates to a vertical injection molding machine hydraulic drive system and injection molding machine. BACKGROUND

[0002] The injection molding machine is internally equipped with a hydraulic drive structure, which includes a main pump, a glue injection cylinder, a glue displacement cylinder, a reversing valve group, a glue melting motor, etc. The glue injection cylinder, the glue displacement cylinder, and the glue melting motor are respectively connected with the oil inlet pipeline and the oil return pipeline through their corresponding reversing valve groups. However, the above-mentioned hydraulic drive structure has the following shortcomings:

[0003] When the glue melting operation is performed on the injection bench, if the glue injection cylinder of the injection molding machine is vertically arranged, the oil liquid of the main pump is completely supplied to the motor to achieve the purpose of full-speed glue melting. At the same time that the motor drives the screw to melt the glue at full speed, the glue pushes the motor backward to retreat upward, and the back pressure value of the glue injection cavity is set to ensure the uniform compaction state of the material. Due to the influence of the motor and the tail plate of the motor, the compaction state of the material is uncontrollable, and the product quality cannot be guaranteed.

[0004] Therefore, there is an urgent need for a vertical injection molding machine hydraulic drive system to solve the above-mentioned technical problems. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a vertical injection molding machine hydraulic drive system, which can more accurately control the compaction state of the molten material.

[0006] To achieve this purpose, the utility model adopts the following technical solutions:

[0007] In a first aspect, a vertical injection molding machine hydraulic drive system is provided, comprising:

[0008] A main pump, the oil inlet of the main pump being in communication with an oil tank;

[0009] A glue displacement control assembly, including a glue displacement control valve and a glue displacement cylinder, the oil inlet of the glue displacement control valve being in communication with the oil outlet of the main pump, and the glue displacement control valve being used to selectively connect the rod cavity or the rodless cavity of the glue displacement cylinder to the oil inlet of the main pump;

[0010] A motor, the motor being used to connect the screw inside the glue melting cylinder;

[0011] A glue injection control assembly, including a glue injection melting control valve and a glue injection cylinder, the glue injection control valve being used to selectively connect the rod cavity of the glue injection cylinder or the oil inlet of the motor to the oil inlet of the main pump, and the tail plate bearing the motor being connected with the piston rod of the glue injection cylinder;

[0012] The stripping control assembly comprises a stripping control valve for controlling the selective communication of the rodless chamber of the injection ram cylinder with the oil tank or the oil outlet of the main pump;

[0013] The auxiliary pump assembly comprises at least an auxiliary pump, and the oil outlet of the auxiliary pump is in communication with the rodless chamber of the injection ram cylinder.

[0014] The back pressure valve has an oil inlet in communication with the oil return port of the injection ram control valve and an oil outlet in communication with the oil tank.

[0015] As a preferred technical solution of the vertical injection molding machine hydraulic drive system, the auxiliary pump assembly further comprises a one-way valve, the oil outlet of the one-way valve is in communication with the rodless chamber of the injection ram cylinder, the oil inlet of the one-way valve is in communication with the oil outlet of the auxiliary pump, and the one-way valve only allows the oil provided by the auxiliary pump to enter the rodless chamber of the injection ram cylinder.

[0016] As a preferred technical solution of the vertical injection molding machine hydraulic drive system, the injection shift control assembly further comprises a hydraulic lock connected between the injection shift cylinder and the injection shift control valve.

[0017] As a preferred technical solution of the vertical injection molding machine hydraulic drive system, a filter is further arranged at the oil inlet of the main pump and the oil inlet of the auxiliary pump.

[0018] As a preferred technical solution of the vertical injection molding machine hydraulic drive system, the rodless chamber of the injection ram cylinder is provided with a first pressure sensor for detecting the pressure of the rodless chamber.

[0019] As a preferred technical solution of the vertical injection molding machine hydraulic drive system, the rod chamber of the injection ram cylinder is provided with a second pressure sensor for detecting the pressure of the rod chamber of the injection ram cylinder.

[0020] As a preferred technical solution of the vertical injection molding machine hydraulic drive system, the injection shift control valve is a three-position four-way electromagnetic valve; and / or,

[0021] The injection ram melt glue control valve is a three-position four-way electromagnetic valve; and / or,

[0022] The stripping control valve is a three-position four-way electromagnetic valve.

[0023] As a preferred technical solution of the vertical injection molding machine hydraulic drive system, an overflow valve is further arranged, the oil inlet of the overflow valve is in communication with the oil outlet of the main pump, and the oil outlet of the overflow valve is in communication with the oil return port of the oil tank.

[0024] As a preferred technical solution of the vertical injection molding machine hydraulic drive system, the auxiliary pump is a constant pressure variable pump.

[0025] In a second aspect, the utility model provides a vertical injection molding machine, including the vertical injection molding machine hydraulic drive system of any scheme.

[0026] The utility model has at least the following beneficial effects:

[0027] The utility model provides a vertical injection molding machine hydraulic drive system and injection molding machine, in the glue melting process, raw material melts and plasticizes state, with raw material constantly accumulates and promotes screw retreat, namely screw moves upwards, at this time, the coil YA1 of glue injection glue melting control valve is electrified, the P mouth of glue injection glue melting control valve and B mouth intercommunication, the A mouth of glue injection glue melting control valve and T mouth intercommunication, the no rod cavity of auxiliary pump provides pressure oil to glue injection oil cylinder, the no rod cavity of auxiliary pump provides constant pressure for glue injection oil cylinder, is used for balancing the influence that motor and tailboard weight bring, in order to avoid that screw retreats too fast, the rod cavity of glue injection oil cylinder is connected with back pressure valve, and back pressure valve and auxiliary pump assembly two cooperation realize that the no rod cavity and the rod cavity of glue injection oil cylinder are in dynamic balance state, so this can guarantee that the raw material of melting can be uniformly compacted, and the density, weight and related size of the product made are more stable. The utility model eliminates the influence that the pressure that motor and the tailboard of installing motor bring to make back pressure control more accurate through auxiliary pump. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical scheme in the embodiment of the utility model, the following will be needed to use the drawing in the embodiment of the utility model is briefly introduced, and obviously, the drawing in the following description is only some embodiments of the utility model, and for those skilled in the art, under the premise of not creating labor, other drawings can also be obtained according to the content of the embodiment of the utility model and these drawings.

[0029] Figure 1 The hydraulic principle view of the vertical injection molding machine hydraulic drive system provided by the embodiment of the utility model is provided;

[0030] Figure 2 The partial schematic view of glue injection control assembly, loose retreat control assembly and glue injection control assembly provided by the embodiment of the utility model is provided.

[0031] In the drawing:

[0032] 1, main pump;2, motor;3, glue injection control valve;4, glue injection oil cylinder;5, glue injection glue melting control valve;6, glue injection oil cylinder;7, loose retreat control valve;8, auxiliary pump;9, back pressure valve;11, check valve;12, hydraulic lock;13, filter;14, first pressure sensor;15, second pressure sensor;16, overflow valve;17, oil tank;100, screw. DETAILED DESCRIPTION

[0033] The utility model will be further described in detail below in combination with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the utility model, and not to limit the utility model. In addition, it should be noted that, in order to facilitate the description, only the part related to the utility model is shown in the drawings, not all structures.

[0034] In the description of the utility model, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the communication between two elements or the interaction between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0035] In the utility model, unless otherwise explicitly specified and limited, the first feature is "on" or "below" the second feature, which can include direct contact between the first and second features, or indirect contact between the first and second features through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0036] In the description of the embodiment, the terms "up", "down", "right", etc. orientation or position relationship is based on the orientation or position relationship shown in the drawings, only for the convenience of description and simplification of operation, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the utility model. In addition, the terms "first", "second" are only used to distinguish in the description, and have no special meaning.

[0037] As Figure 1 And Figure 2The utility model discloses a vertical injection molding machine hydraulic drive system, vertical injection molding machine hydraulic drive system includes main pump 1, motor 2, shoot shift control subassembly, shoot glue control subassembly, loose retreat control subassembly, vice pump subassembly 8 and back pressure valve 9, wherein the oil inlet of main pump 1 is communicated with oil tank 17, and motor 2 is used for being connected with screw 100, shoot shift control subassembly includes shoot shift control valve 3 and shoot shift oil cylinder 4, and the oil inlet of shoot shift control valve 3 is communicated with the oil outlet of main pump 1, and shoot shift control valve 3 is used for controlling the oil inlet of main pump 1 to selectively communicate the rod cavity or the rod cavity of shoot shift oil cylinder 4, shoot glue control subassembly includes shoot glue melt glue control valve 5 and shoot glue oil cylinder 6, and shoot glue melt glue control valve 5 is used for controlling the oil inlet of main pump 1 to selectively communicate the rod cavity of shoot glue oil cylinder 6 or the oil inlet of motor 2, loose retreat control subassembly includes loose retreat control valve 7, and loose retreat control valve 7 is used for controlling the rod cavity of shoot glue oil cylinder 6 to selectively communicate oil tank 17 or the oil outlet of main pump 1, vice pump subassembly 8 includes at least vice pump 8, and the oil outlet of vice pump 8 is communicated with the rod cavity of shoot shift oil cylinder 4, and the oil inlet of back pressure valve 9 is communicated with the oil return of shoot glue melt glue control valve 5, and the oil outlet of back pressure valve 9 is communicated with oil tank 17.

[0038] The utility model discloses a vertical injection molding machine hydraulic drive system, in the melt glue process, raw material melts and plasticizes state, with raw material constantly accumulates and promotes screw 100 to retreat, namely screw 100 moves upwards, the coil YA1 of shoot glue melt glue control valve 5 is electrified at this time, and the P port of shoot glue melt glue control valve 5 is communicated with B port, and the A port of shoot glue melt glue control valve 5 is communicated with T port (i.e. oil return), and vice pump 8 provides pressure oil to enter the rod cavity of shoot glue oil cylinder 6, and vice pump 8 provides constant pressure for the rod cavity of shoot glue oil cylinder 6, for balancing the influence of motor 2 and tailboard weight, in order to avoid that screw 100 retreats too fast, the rod cavity of shoot glue oil cylinder 6 is connected with back pressure valve 9, and back pressure valve 9 and vice pump subassembly two cooperation to realize that the rod cavity and the rod cavity of shoot glue oil cylinder 6 are in dynamic balance state, and this can guarantee that the raw material of melting can be evenly compacted, and the density, weight and related size of the product of beating are more stable. The utility model passes through vice pump 8 and eliminates the influence that the pressure of motor 2 and the tailboard of installing motor 2 causes, makes back pressure control more accurate.

[0039] The number of shoot glue oil cylinder 6 is at least two, and the piston rod of each shoot glue oil cylinder 6 is connected with the tailboard, wherein the rod cavity of shoot glue oil cylinder 6 is communicated, and the rod cavity of shoot glue oil cylinder 6 is communicated. By thus setting, it can be guaranteed that shoot glue oil cylinder 6 can stably support the tailboard, and the pressure of each place of the rod cavity is balanced, and the pressure of each place of the rod cavity is balanced, avoiding the inclination of the tailboard and leading to the inclination of screw 100.

[0040] Further, the auxiliary pump assembly further comprises a one-way valve 11, an oil outlet of the one-way valve 11 is communicated with the rodless cavity of the injection oil cylinder 6, an oil inlet of the one-way valve 11 is communicated with the oil outlet of the auxiliary pump 8, and the one-way valve 11 only allows the oil provided by the auxiliary pump 8 to enter the rodless cavity of the injection oil cylinder 6. The one-way valve 11 can avoid the oil in the injection oil cylinder 6 from entering the auxiliary pump 8, and ensure the oil amount in the injection oil cylinder 6.

[0041] In some embodiments, the auxiliary pump 8 is a constant pressure variable pump. The constant pressure variable pump can adjust the flow of hydraulic oil entering the rodless cavity of the injection oil cylinder 6. For example, the auxiliary pump 8 comprises a pump body and a swash plate angle adjusting assembly. The swash plate angle adjusting assembly is a prior art, and will not be described in detail here.

[0042] In some embodiments, the injection moving control assembly further comprises a hydraulic lock 12 connected between the injection moving oil cylinder 4 and the injection moving control valve 3. The hydraulic lock 12 can ensure the pressure of the injection moving oil cylinder 4, and further ensure that the entire injection platform does not fall during the injection moving process. The specific structure of the hydraulic lock 12 is a prior art, and will not be described in detail here.

[0043] In some embodiments, the vertical injection molding machine hydraulic drive system further comprises a filter 13 connected to the oil inlets of the main pump 1 and the auxiliary pump 8. The filter 13 can prevent impurities in the hydraulic oil from entering the main pump 1 and the auxiliary pump 8, avoid the main pump 1 and the auxiliary pump 8 being worn by impurities, and improve the safety of the main pump 1 and the auxiliary pump 8.

[0044] In some embodiments, the rodless cavity of the injection oil cylinder 6 is provided with a first pressure sensor 14 for detecting the pressure of the rodless cavity, and the rod cavity of the injection oil cylinder 6 is provided with a second pressure sensor 15 for detecting the pressure of the rod cavity. The first pressure sensor 14 is used to detect the pressure in the rodless cavity of the injection oil cylinder 6, and the second pressure sensor 15 is used to detect the pressure in the rod cavity of the injection oil cylinder 6, so as to realize real-time acquisition of the pressures in the rodless cavity and the rod cavity of the injection oil cylinder 6, and control the working of the auxiliary pump 8 and the injection melt glue control valve 5 according to the acquired pressures.

[0045] For example, the injection moving control valve 3 is a three-position four-way electromagnetic valve. In this way, the reversing needs of different oil cylinders can be realized.

[0046] For example, the injection melt glue control valve 5 is a three-position four-way electromagnetic valve. In this way, the reversing needs of different oil cylinders can be realized.

[0047] For example, the loose release control valves 7 are all three-position four-way electromagnetic valves. In this way, the reversing needs of different oil cylinders can be realized.

[0048] In some embodiments, the vertical injection molding machine hydraulic drive system further comprises an overflow valve 16, the oil inlet of the overflow valve 16 is communicated with the oil outlet of the main pump 1, and the oil outlet of the overflow valve 16 is communicated with the oil return port of the oil tank 17. And the overflow valve 16 is used to ensure that the oil pressure of the injection oil cylinder 6 is constant when the rodless cavity of the injection oil cylinder 6 is in and out of hydraulic oil, so as to avoid the increase of oil pressure caused by the sudden increase of oil flow, and then realize the accurate control of the lifting and falling of the injection oil cylinder 6.

[0049] Combining Figure 1 And Figure 2 As shown in the vertical injection molding machine hydraulic drive system working process is as follows:

[0050] The injection seat advances: the right position YA6 of the injection shift control valve 3 is powered on, the high-pressure oil passes through the injection shift control valve 3 and the hydraulic lock 12, enters the rod cavity of the injection shift oil cylinder 4, and the oil in the rodless cavity of the injection shift oil cylinder 4 returns to the oil tank 17 through the hydraulic lock 12 and the injection shift control valve 3.

[0051] The injection seat advances: the left position YA5 of the injection shift control valve 3 is powered on, the high-pressure oil passes through the injection shift control valve 3 and the hydraulic lock 12, enters the rodless cavity of the injection shift oil cylinder 4, and the oil in the rodless cavity of the injection shift oil cylinder 4 returns to the oil tank 17 through the hydraulic lock 12 and the injection shift control valve 3.

[0052] Injection process:

[0053] The right position YA2 of the injection melt control valve 5 is powered on, the high-pressure oil passes through the injection melt control valve 5 and enters the rod cavity of the injection oil cylinder 6, and the oil in the rodless cavity returns to the oil tank through the left position YA3 of the loose control valve 7. The power is on, and the injection action is completed.

[0054] Loose process:

[0055] The right position YA4 of the loose control valve 7 is powered on, the high-pressure oil passes through the loose control valve 7 and enters the rodless cavity of the injection oil cylinder 6, and the oil in the rodless cavity returns to the oil tank 17 through the injection melt control valve 5 and the back pressure valve 9.

[0056] Melt process:

[0057] The secondary pump 8 provides pressure oil, which enters the rodless cavity of the injection melt oil cylinder 6 through the one-way valve 11, and the secondary pump 8 provides constant pressure (motor 2 and tail plate weight / injection melt oil cylinder 6 rodless cavity area) for balancing the influence of the weight of the motor 2 and the tail plate structure.

[0058] The high-pressure oil of the main pump 1 enters the motor 2 through the injection melt control valve 5, and at this time the left position YA1 of the injection melt control valve 5 is powered on, and the back pressure of the rod cavity of the injection oil cylinder 6 is controlled by the back pressure valve 9.

[0059] The utility model provides a kind of injection molding machine, including vertical injection molding machine hydraulic drive system provided by the embodiment.

[0060] Since the injection molding machine comprises the vertical injection molding machine hydraulic drive system, in the glue melting process, the raw material is in the molten plasticized state, and the screw 100 retreats with the continuous accumulation of the raw material, that is, the screw 100 moves upward, at this time, the coil YA1 of the glue injection and melting control valve 5 is electrified, the P port and the B port of the glue injection and melting control valve 5 are communicated, the A port and the T port of the glue injection and melting control valve 5 are communicated, the auxiliary pump 8 provides pressure oil into the rodless cavity of the glue injection oil cylinder 6, the auxiliary pump 8 provides constant pressure for the rodless cavity of the glue injection oil cylinder 6, and the auxiliary pump 8 is used for balancing the influence of the motor 2 and the tail plate weight, in order to avoid that the screw 100 retreats too fast, the rod cavity of the glue injection oil cylinder 6 is connected with the back pressure valve 9, the back pressure valve 9 and the auxiliary pump assembly are cooperated to realize that the rodless cavity and the rod cavity of the glue injection oil cylinder 6 are in dynamic balance state, so that the molten raw material can be uniformly compacted, and the density, weight and related size of the product are more stable. The utility model discloses a motor 2 and the tail plate for installing the motor 2 are eliminated by the auxiliary pump 8, the influence caused by the pressure, the back pressure control is more accurate.

[0061] Since the injection molding machine comprises the vertical injection molding machine hydraulic drive system, in the glue melting process, the raw material is in the molten plasticized state, and the screw 100 retreats with the continuous accumulation of the raw material, that is, the screw 100 moves upward, at this time, the coil YA1 of the glue injection and melting control valve 5 is electrified, the P port and the B port of the glue injection and melting control valve 5 are communicated, the A port and the T port of the glue injection and melting control valve 5 are communicated, the auxiliary pump 8 provides pressure oil into the rodless cavity of the glue injection oil cylinder 6, the auxiliary pump 8 provides constant pressure for the rodless cavity of the glue injection oil cylinder 6, and the auxiliary pump 8 is used for balancing the influence of the motor 2 and the tail plate weight, in order to avoid that the screw 100 retreats too fast, the rod cavity of the glue injection oil cylinder 6 is connected with the back pressure valve 9, the back pressure valve 9 and the auxiliary pump assembly are cooperated to realize that the rodless cavity and the rod cavity of the glue injection oil cylinder 6 are in dynamic balance state, so that the molten raw material can be uniformly compacted, and the density, weight and related size of the product are more stable. The utility model discloses a motor 2 and the tail plate for installing the motor 2 are eliminated by the auxiliary pump 8, the influence caused by the pressure, the back pressure control is more accurate.

[0062] In addition, the above is only the preferred embodiment of the utility model and the technical principle used. Those skilled in the art will understand that the utility model is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, re-adjustment and replacement without departing from the protection scope of the utility model. Therefore, although the utility model is more specifically described through the above embodiments, the utility model is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the utility model concept, and the scope of the utility model is determined by the appended claims.

Claims

1. A hydraulic drive system for a vertical injection molding machine, characterized by, The system comprises: a main pump (1), an oil inlet of which is communicated with an oil tank (17); a shift control assembly comprising a shift control valve (3) and a shift oil cylinder (4), an oil inlet of the shift control valve (3) is communicated with an oil outlet of the main pump (1), the shift control valve (3) is used for controlling the oil inlet of the main pump (1) to selectively communicate with a rod cavity or a rodless cavity of the shift oil cylinder (4); a motor (2) used for connecting a screw (100) inside a glue melting cylinder; a glue injection control assembly comprising a glue injection melting control valve (5) and a glue injection oil cylinder (6), the glue injection melting control valve (5) is used for controlling the oil inlet of the main pump (1) to selectively communicate with a rod cavity of the glue injection oil cylinder (6) or an oil inlet of the motor (2), a tail plate bearing the motor (2) is connected with a piston rod of the glue injection oil cylinder (6); a loosening control assembly comprising a loosening control valve (7), the loosening control valve (7) is used for controlling a rodless cavity of the glue injection oil cylinder (6) to selectively communicate with the oil tank (17) or the oil outlet of the main pump (1); a sub-pump assembly, the sub-pump assembly at least comprises a sub-pump (8), an oil outlet of the sub-pump (8) is communicated with the rodless cavity of the shift oil cylinder (4); a back pressure valve (9), an oil inlet of the back pressure valve (9) is communicated with an oil return port of the glue injection melting control valve (5), an oil outlet of the back pressure valve (9) is communicated with the oil tank (17).

2. The hydraulic drive system for a vertical injection molding machine of claim 1 wherein, The sub-pump assembly further comprises a one-way valve (11), an oil outlet of the one-way valve (11) is communicated with the rodless cavity of the glue injection oil cylinder (6), an oil inlet of the one-way valve (11) is communicated with the oil outlet of the sub-pump (8), the one-way valve (11) only allows the oil provided by the sub-pump (8) to enter the rodless cavity of the glue injection oil cylinder (6).

3. The hydraulic drive system for a vertical injection molding machine of claim 1 wherein, The shift control assembly further comprises a hydraulic lock (12) connecting the shift oil cylinder (4) and the shift control valve (3).

4. The hydraulic drive system for a vertical injection molding machine of claim 1 wherein, Further comprising a filter (13), the oil inlet of the main pump (1) and the oil inlet of the sub-pump (8) are both connected with the filter (13).

5. The hydraulic drive system for a vertical injection molding machine according to any one of claims 1 to 4, characterized in that, The rodless cavity of the glue injection oil cylinder (6) is provided with a first pressure sensor (14) used for detecting the pressure of the rodless cavity.

6. The hydraulic drive system for a vertical injection molding machine of any of claims 1-4, wherein, The rod cavity of the glue injection oil cylinder (6) is provided with a second pressure sensor (15) used for detecting the pressure of the rod cavity of the glue injection oil cylinder (6).

7. The hydraulic drive system for a vertical injection molding machine of any of claims 1-4, wherein, The shift control valve (3) is a three-position four-way electromagnetic valve; and / or, The glue injection melting control valve (5) is a three-position four-way electromagnetic valve; and / or, The loosening control valve (7) is a three-position four-way electromagnetic valve.

8. The hydraulic drive system for a vertical injection molding machine of any of claims 1-4, wherein, Further comprising an overflow valve (16), an oil inlet of the overflow valve (16) is communicated with an oil outlet of the main pump (1), an oil outlet of the overflow valve (16) is communicated with an oil return port of the oil tank (17).

9. The hydraulic drive system for a vertical injection molding machine of any of claims 1-4, wherein, The sub-pump (8) is a constant pressure variable pump.

10. An injection molding machine characterized by, The system comprises the vertical injection molding machine hydraulic drive system according to any one of claims 1-9. The system comprises the vertical injection molding machine hydraulic drive system according to any one of claims 1-9.

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