Injection molding machine hydraulic system and injection molding machine hydraulic control method

Abstract

The present invention belongs to the field of injection molding technology, and discloses an injection molding machine hydraulic system and an injection molding machine hydraulic control method. In the injection molding machine hydraulic system, an oil tank, an output end of a first oil pump and an oil inlet P1 are connected in sequence. The first oil return control valve can selectively open and close the oil inlet and outlet E1 and the oil inlet and outlet F1. When the oil inlet and outlet E1 are connected to the oil inlet and outlet F1, the first rod chamber, the first oil return cartridge valve and the first rodless chamber are connected in sequence. The oil inlet E2 and the oil inlet P2 are both connected to the output end of the first oil pump. The second oil inlet control valve can selectively open and close the oil inlet E2 and the oil outlet F2. When the oil inlet E2 and the oil outlet F2 are connected, the first oil pump, the second oil inlet check valve and the first rodless chamber are connected in sequence. In the process of electromelting glue, the oil can be replenished synchronously and accurately to reduce the influence caused by the vacuum generated in the first rodless chamber, and the injection molding cycle can be shortened, the stability of the quality of the product obtained by injection molding is guaranteed, and energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of injection molding, and in particular to a hydraulic system of an injection molding machine and a hydraulic control method of the injection molding machine. Background Art

[0002] Injection molding equipment usually consists of a mold, a plasticizing injection system, a clamping system, etc. Among them, the function of the plasticizing injection system is to heat and plasticize a certain amount of material within a specified time, and then inject the molten material into the mold cavity through a screw at a certain pressure and speed. After the injection is completed, the mold maintains the shape of the molten material injected into the mold cavity. The function of the clamping system is to ensure the closure, opening and ejection of the mold; after the mold is closed, sufficient clamping force is applied to the mold to resist the cavity pressure generated by the molten material entering the mold cavity, to prevent the mold from opening and affecting the quality of the manufactured product.

[0003] For the injection system, the rod chamber of the injection cylinder is usually set corresponding to the melting and injection process, that is, during this process, hydraulic oil is transported to the rod chamber through the hydraulic system; the rodless chamber of the injection cylinder is corresponding to the loosening process, that is, during this process, hydraulic oil is transported to the rodless chamber through the hydraulic system. Among them, because the screw rotates and eats the material during the melting process, the screw is easily retreated by the reaction force exerted by the material in the process of conveying the material to its front end, and the screw retreat will synchronously drive the piston rod of the injection cylinder to move, resulting in a large amount of vacuum in the oil chamber corresponding to the loosening process. In response to this phenomenon, the following two coping methods are usually adopted in the prior art. One is to add oil to the oil chamber corresponding to the loosening process after the melting is completed to eliminate the vacuum, but this method will cause the loosening process to last longer, thereby resulting in a long injection molding cycle; the other is to directly add oil to the oil chamber corresponding to the loosening process through the oil pump, but this method will increase energy consumption, and the oil pump has low control accuracy on the low pressure, and the pressure fluctuation will cause uneven melting speed, resulting in unstable plasticization of the material, resulting in unstable quality of the product obtained by injection molding. Summary of the invention

[0004] The purpose of the present invention is to provide an injection molding machine hydraulic system and an injection molding machine hydraulic control method to solve the above-mentioned problems existing in the hydraulic system in the prior art.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] The hydraulic system of an injection molding machine comprises an injection cylinder, wherein the injection cylinder comprises a first cylinder body and a first piston rod slidably arranged on the first cylinder body, wherein the first piston rod divides the first cylinder body into a first rod chamber and a first rodless chamber; one end of the first piston rod extending out of the first cylinder body is transmission-connected to an injection molding screw and can drive the injection molding screw to move along its own axial direction; the hydraulic system of the injection molding machine further comprises:

[0007] The first oil return combination valve comprises a first oil return cartridge valve and a first oil return control valve, wherein the oil inlet P1 of the first oil return control valve is connected to the output end of the first oil pump, and the input end of the first oil pump is connected to the oil tank; the first oil return control valve can selectively open and close the oil inlet and outlet E1 and the oil inlet and outlet F1 of the first oil return cartridge valve, and when the oil inlet and outlet E1 and the oil inlet and outlet F1 are connected, the first rod chamber, the first oil return cartridge valve and the first rodless chamber are connected in sequence;

[0008] The second oil inlet combination valve includes a second oil inlet check valve and a second oil inlet control valve. The oil inlet E2 of the second oil inlet check valve and the oil inlet P2 of the second oil inlet control valve are both connected to the output end of the first oil pump. The second oil inlet control valve can selectively open and close the oil inlet E2 and the oil outlet F2 of the second oil inlet check valve. When the oil inlet E2 and the oil outlet F2 are connected, the first oil pump, the second oil inlet check valve and the first rodless chamber are connected in sequence.

[0009] As a preferred solution of the above-mentioned hydraulic system of the injection molding machine, the first oil return control valve is a two-position four-way pilot solenoid valve, the communication port A1 of the first oil return control valve is connected to the first pilot oil port G1 of the first oil return cartridge valve, the communication port B1 of the first oil return control valve is blocked, and the oil return port T1 of the first oil return control valve is connected to the oil tank;

[0010] When the first oil return control valve is energized, the oil inlet P1 is connected to the connecting port B1, and the connecting port A1 is connected to the oil return port T1; when the first oil return control valve is de-energized, the oil inlet P1 is connected to the connecting port A1, and the connecting port B1 is connected to the oil return port T1.

[0011] As a preferred solution of the above-mentioned hydraulic system of the injection molding machine, the hydraulic system of the injection molding machine further includes a first on-off valve, and the first on-off valve can selectively open and close the first rodless chamber and the oil tank.

[0012] As a preferred solution of the above-mentioned hydraulic system of the injection molding machine, the hydraulic system of the injection molding machine further includes:

[0013] A first oil inlet combination valve comprises a first oil inlet check valve and a first oil inlet control valve, wherein the oil inlet port E3 of the first oil inlet check valve and the oil inlet port P3 of the first oil inlet control valve are both connected to the output end of the first oil pump, and the first oil inlet control valve can selectively open and close the oil inlet port E3 and the oil outlet port F3 of the first oil inlet check valve, and when the oil inlet port E3 and the oil outlet port F3 are connected, the first oil pump, the first oil inlet check valve and the first rod chamber are connected in sequence;

[0014] The second oil return combination valve includes a second oil return cartridge valve and a second oil return control valve. The oil inlet P4 of the second oil return control valve is connected to the output end of the first oil pump. The second oil return control valve can selectively open and close the oil inlet and outlet E4 and the oil inlet and outlet F4 of the second oil return cartridge valve. When the oil inlet and outlet E4 and the oil inlet and outlet F4 are connected, the first rodless chamber, the second oil return cartridge valve and the oil tank are connected in sequence.

[0015] As a preferred solution of the above-mentioned injection molding machine hydraulic system, the injection molding machine hydraulic system also includes a proportional reversing regulating valve; the proportional reversing regulating valve can selectively connect the output end of the first oil pump with the first rodless chamber, and the first rod chamber with the oil tank; or, connect the output end of the first oil pump with the first rod chamber, and the first rodless chamber with the oil tank; or, disconnect the output end of the first oil pump, the oil tank, the first rod chamber and the first rodless chamber from each other.

[0016] As a preferred solution of the above-mentioned hydraulic system of the injection molding machine, the hydraulic system of the injection molding machine also includes a shot displacement cylinder, the shot displacement cylinder includes a second cylinder body and a second piston rod slidably arranged on the second cylinder body, the second piston rod divides the second cylinder body into a second rod chamber and a second rodless chamber, one end of the second piston rod extending out of the second cylinder body is transmission-connected to the mold and can drive the mold to press against the nozzle, so that the nozzle can communicate with the feed port of the mold and the discharge port of the injection molding shell;

[0017] The injection molding machine hydraulic system also includes a first reversing regulating valve and a pressure-maintaining valve, wherein the first reversing regulating valve can selectively connect the output end of the first oil pump with the oil inlet E5 of the pressure-maintaining valve, and the second rodless chamber with the oil tank; or connect the output end of the first oil pump with the second rodless chamber, and the oil inlet E5 of the pressure-maintaining valve with the oil tank; or, the oil inlet E5 of the pressure-maintaining valve is connected with the oil tank, and the second rodless chamber is closed;

[0018] The oil outlet F5 of the pressure-maintaining valve is connected to the second rod chamber;

[0019] The pressure-maintaining valve can selectively allow the oil inlet E5 and the oil outlet F5 to communicate with each other; or, the oil inlet E5 and the oil outlet F5 can be unidirectionally communicated.

[0020] The hydraulic control method of an injection molding machine is used to be implemented in the above-mentioned hydraulic system of the injection molding machine, and the hydraulic control method of the injection molding machine includes:

[0021] During the electromelting process, determining whether the first rodless chamber generates a vacuum according to the moving direction and the moving amount of the first piston rod;

[0022] If the first rodless chamber generates a vacuum, the first oil return control valve is controlled to connect the oil inlet and outlet E1 with the oil inlet and outlet F1; the second oil inlet control valve is synchronously controlled to connect the oil inlet E2 with the oil outlet F2; the oil replenishment voltage is synchronously calculated and the voltage of the first oil pump is adjusted to the oil replenishment voltage.

[0023] As a preferred solution of the above-mentioned hydraulic control method for the injection molding machine, the calculation formula for calculating the oil replenishment voltage U(t) is:

[0024] Q(t)=π*r*r*V(t) / 2;

[0025] n(t)=Q(t) / V(row);

[0026] U(t)=n(t)*60*set voltage value / N;

[0027] Where r is the radius of the first piston rod, mm; V(t) is the ratio of the movement change of the injection screw to the time change of the electric melt glue, mm / s; Q(t) is the total required oil replenishment of the first rodless chamber, mm 3 / s; V(displacement) is the displacement of the first oil pump, mm 3 / r; n(t) is the number of revolutions required by the first oil pump per second, r / s; N is the maximum rated number of revolutions per minute of the first oil pump under the set voltage value, r / min.

[0028] As a preferred solution of the above-mentioned hydraulic control method for the injection molding machine, the hydraulic system of the injection molding machine further includes a first on-off valve, and the first on-off valve can selectively open and close the first rodless chamber and the oil tank;

[0029] If the first rodless chamber generates a vacuum, the first on-off valve is synchronously controlled to connect the first rodless chamber and the oil tank.

[0030] As a preferred solution of the above-mentioned hydraulic control method for the injection molding machine, a back pressure proportional regulating valve is provided on the pipeline connecting the oil return port T1 of the first oil return control valve and the oil tank; the hydraulic system of the injection molding machine also includes a proportional reversing regulating valve, which can selectively connect the output end of the first oil pump and the first rodless chamber, and the first rod chamber and the oil tank;

[0031] The injection molding machine hydraulic control method also includes:

[0032] When the injection screw is loosened, the first oil return control valve is controlled to connect the oil inlet and outlet E1 with the oil inlet and outlet F1; the second oil inlet control valve is synchronously controlled to connect the oil inlet E2 with the oil outlet F2, and the first oil pump pumps oil to the oil inlet E2; the back pressure proportional regulating valve is controlled to be powered off;

[0033] After the first set time, the first oil return control valve is controlled to disconnect the oil inlet and outlet E1 and the oil inlet and outlet F1; the second oil inlet control valve is synchronously controlled to disconnect the oil inlet E2 and the oil outlet F2; the proportional reversing regulating valve is synchronously controlled to connect the output end of the first oil pump and the first rodless chamber, and the first rod chamber and the oil tank are connected, and the first oil pump pumps oil into the first rodless chamber.

[0034] Beneficial effects of the present invention:

[0035] The present invention provides an injection molding machine hydraulic system and an injection molding machine hydraulic control method. The injection molding machine hydraulic system includes a shot-molding cylinder, a first oil return combination valve and a second oil inlet combination valve. The shot-molding cylinder includes a first cylinder body and a first piston rod slidably arranged on the first cylinder body, and the first piston rod divides the first cylinder body into a first rod chamber and a first rodless chamber. One end of the first piston rod extending out of the first cylinder body is transmission-connected to the injection molding screw and can drive the injection molding screw to move along its own axial direction. The first oil return combination valve includes a first oil return cartridge valve and a first oil return control valve. The oil inlet P1 of the first oil return control valve is connected to the output end of the first oil pump, and the input end of the first oil pump is connected to the oil tank. The first oil return control valve can selectively open and close the oil inlet and outlet E1 and the oil inlet and outlet F1 of the first oil return cartridge valve. When the oil inlet and outlet E1 are connected to the oil inlet and outlet F1, the first rod chamber, the first oil return cartridge valve and the first rodless chamber are connected in sequence. The second oil inlet combination valve includes a second oil inlet check valve and a second oil inlet control valve, and the oil inlet port E2 of the second oil inlet check valve and the oil inlet port P2 of the second oil inlet control valve are both connected to the output end of the first oil pump. The second oil inlet control valve can selectively open and close the oil inlet port E2 and the oil outlet F2 of the second oil inlet check valve. When the oil inlet port E2 and the oil outlet F2 are connected, the first oil pump, the second oil inlet check valve and the first rodless chamber are connected in sequence.

[0036] By adopting the hydraulic system of the injection molding machine, the influence of the vacuum generated in the first rodless cavity can be effectively reduced during the process of electric melting glue, and the injection molding cycle can be effectively shortened; secondly, the pressure fluctuation caused by the oil replenishment to the first rodless cavity by the first oil pump can be effectively reduced, and the stability of the quality of the product obtained by injection molding can be effectively guaranteed, and the energy consumption caused by the first oil pump replenishing oil to the first rodless cavity can be effectively reduced; thirdly, the amount of oil replenished to the first rodless cavity by the first oil pump can be accurately controlled, and excessive oil replenishment can be effectively avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic diagram of a hydraulic system for an injection molding machine provided by a specific embodiment of the present invention;

[0038] Figure 2 is a first flow chart of a hydraulic control method for an injection molding machine provided by a specific embodiment of the present invention;

[0039] Figure 3 is a second flow chart of the hydraulic control method for an injection molding machine provided by a specific embodiment of the present invention;

[0040] Figure 4 It is the third flow chart of the hydraulic control method of the injection molding machine provided by the specific embodiment of the present invention.

[0041] In the figure:

[0042] 11. Injection cylinder; 111. First piston rod; 112. First rod chamber; 113. First rodless chamber; 12. Injection screw; 13. Motor; 14. Electronic ruler;

[0043] 21. First oil return cartridge valve; 22. First oil return control valve; 23. Back pressure proportional regulating valve; 24. Mechanical check valve; 25. First throttle valve;

[0044] 31. Second oil inlet check valve; 32. Second oil inlet control valve; 33. Second throttle valve;

[0045] 4. The first on-off valve;

[0046] 51. First oil inlet check valve; 52. First oil inlet control valve; 53. Third throttle valve;

[0047] 61. Second oil return cartridge valve; 62. Second oil return control valve; 63. Fourth throttle valve;

[0048] 7. Proportional reversing regulating valve;

[0049] 81, injection cylinder; 811, second piston rod; 812, second rod chamber; 813, second rodless chamber; 82, first reversing regulating valve; 83, pressure maintaining valve;

[0050] 91. first oil pump; 92. oil tank; 93. second on-off valve; 94. second oil pump;

[0051] 101, a first pressure sensor; 102, a pressure gauge; 103, a third pressure sensor; 104, a fourth pressure sensor;

[0052] 120. Shuttle valve;

[0053] 130, nozzle cylinder; 131, nozzle; 132, second reversing regulating valve;

[0054] 140. Clamping system. DETAILED DESCRIPTION

[0055] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0056] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0058] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0059] like Figure 1As shown, the present invention provides a hydraulic system for an injection molding machine, which includes a shot-molding cylinder 11, a first oil return combination valve and a second oil inlet combination valve. The shot-molding cylinder 11 includes a first cylinder body and a first piston rod 111 slidably disposed on the first cylinder body, and the first piston rod 111 divides the first cylinder body into a first rod chamber 112 and a first rodless chamber 113. One end of the first piston rod 111 extending out of the first cylinder body is transmission-connected to the injection screw 12 and can drive the injection screw 12 to move along its own axial direction. The first oil return combination valve includes a first oil return cartridge valve 21 and a first oil return control valve 22. The oil inlet P1 of the first oil return control valve 22 is connected to the output end of the first oil pump 91, and the input end of the first oil pump 91 is connected to the oil tank 92. The first oil return control valve 22 can selectively open and close the oil inlet and outlet E1 and the oil inlet and outlet F1 of the first oil return cartridge valve 21. When the oil inlet and outlet E1 are connected to the oil inlet and outlet F1, the first rod chamber 112, the first oil return cartridge valve 21 and the first rodless chamber 113 are connected in sequence. The second oil inlet combination valve includes a second oil inlet check valve 31 and a second oil inlet control valve 32, and the oil inlet E2 of the second oil inlet check valve 31 and the oil inlet P2 of the second oil inlet control valve 32 are both connected to the output end of the first oil pump 91. The second oil inlet control valve 32 can selectively open and close the oil inlet E2 and the oil outlet F2 of the second oil inlet check valve 31. When the oil inlet E2 and the oil outlet F2 are connected, the first oil pump 91, the second oil inlet check valve 31 and the first rodless chamber 113 are connected in sequence.

[0060] During the process of conveying materials through the injection screw 12, if the material accumulated at the front end of the injection screw 12 along the axial direction reaches a certain amount, the material will apply a reaction force to the injection screw 12 to make the injection screw 12 move axially from the first rodless cavity 113 to the first rod cavity 112, so that a vacuum is generated in the first rodless cavity 113. When a vacuum is generated in the first rodless cavity 113, the first oil return control valve 22 is controlled to connect the oil inlet and outlet E1 with the oil inlet and outlet F1, so that the first rod cavity 112, the first oil return cartridge valve 21 and the first rodless cavity 113 are connected in sequence, so that the hydraulic oil flowing out of the first rod cavity 112 is directly replenished in the first rodless cavity 113. At the same time, the second oil inlet control valve 32 is controlled to connect the oil inlet E2 and the oil outlet F2, so that the first oil pump 91, the second oil inlet check valve 31 and the first rodless chamber 113 are connected in sequence, and the first oil pump 91 pumps the hydraulic oil in the oil tank 92 into the first rodless chamber 113 to replenish oil to the first rodless chamber 113. This makes it possible to effectively reduce the impact of the vacuum generated in the first rodless cavity 113 during the electromelting process compared to the prior art, and can effectively shorten the injection molding cycle; secondly, such an arrangement makes it possible for most of the hydraulic oil used to replenish the first rodless cavity 113 to come from the first rod cavity 112, and a small part of the hydraulic oil to come from the hydraulic oil pumped from the oil tank 92 to the first rodless cavity 113 by the first oil pump 91, thereby effectively reducing the amount of oil pumped from the oil tank 92 to the first rodless cavity 113 for replenishment by the first oil pump 91 compared to the prior art, so as to effectively reduce the pressure fluctuation caused by the oil replenishment to the first rodless cavity 113 by the first oil pump 91, thereby effectively ensuring the stability of the quality of the product obtained by injection molding, and effectively reducing the energy consumption of the first oil pump 91 due to the oil replenishment to the first rodless cavity 113.

[0061] Secondly, such a configuration makes it possible to calculate the amount of oil that is pumped from the oil tank 92 by the first oil pump 91 to the first rodless cavity 113 for replenishing the oil based on the relevant parameters of the injection screw 12 and the injection cylinder 11, thereby being able to calculate the oil replenishing voltage applied to the first oil pump 91, and to control the first oil pump 91 to pump the hydraulic oil in the oil tank 92 into the first rodless cavity 113 through the calculated oil replenishing voltage to replenish the first rodless cavity 113, so that the amount of oil replenished to the first rodless cavity 113 by the first oil pump 91 can be accurately controlled, thereby being able to effectively avoid excessive oil replenishment, to further ensure the stability of the quality of the products obtained by injection molding.

[0062] Therefore, by adopting the hydraulic system of the injection molding machine, the impact of the vacuum generated in the first rodless cavity 113 can be effectively reduced during the electric melt process, and the injection molding cycle can be effectively shortened; secondly, the pressure fluctuation caused by the oil replenishment to the first rodless cavity 113 by the first oil pump 91 can be effectively reduced, and the stability of the quality of the product obtained by injection molding can be effectively guaranteed, and the energy consumption caused by the first oil pump 91 replenishing oil to the first rodless cavity 113 can be effectively reduced; secondly, the amount of oil replenished to the first rodless cavity 113 by the first oil pump 91 can be accurately controlled, and excessive oil replenishment can be effectively avoided.

[0063] Specifically, if the injection screw 12 moves axially from the first rodless cavity 113 to the first rod cavity 112, so that a vacuum is generated in the first rodless cavity 113, the calculation formula for calculating the oil replenishment voltage U(t) is:

[0064] V(t)=△L / △t;

[0065] Q(t)=π*r*r*V(t) / 2;

[0066] n(t)=Q(t) / V(row);

[0067] U(t)=n(t)*60*set voltage value / N;

[0068] Wherein, △L is the change in the distance of the injection molding screw 12 moving axially from the first rodless cavity 113 to the first rod cavity 112, mm. △t is the time change of moving △L, s. V(t) is the ratio of the change in the distance of the injection molding screw 12 moving axially from the first rodless cavity 113 to the first rod cavity 112 to the time change, mm / s. r is the radius of the first piston rod 111, mm. Q(t) is the total required oil replenishment amount of the first rodless cavity 113, mm 3 / s. V(displacement) is the displacement of the first oil pump 91, mm 3 / r. n(t) is the number of revolutions required by the first oil pump 91 per second, r / s. N is the maximum rated number of revolutions per minute of the first oil pump 91 under the set voltage value, r / min. The set voltage value is a value less than or equal to the maximum allowable voltage value of the first oil pump 91.

[0069] It can be understood that the amount of change in the distance that the injection screw 12 moves axially from the first rodless cavity 113 to the first rod cavity 112 is equal to the amount of change in the distance that the first piston rod 111 moves axially from the first rodless cavity 113 to the first rod cavity 112. This allows the amount of oil added to the first rodless cavity 113 by the first oil pump 91 to be accurately controlled.

[0070] In this embodiment, taking the case where the number of the injection cylinders 11 is two as an example, the two injection cylinders 11 are connected in parallel, and the oil replenishment voltage U(t)=2*n(t)*60*set voltage value / N.

[0071] Specifically, the hydraulic system of the injection molding machine further includes an electronic ruler 14, which is used to monitor the real-time position of a fixed point on the injection screw 12. This facilitates determining the amount of change in the movement distance of the injection screw 12 in the axial direction from the first rodless cavity 113 to the first rod cavity 112. The specific structure of the electronic ruler 14 belongs to the prior art and will not be described in detail here.

[0072] Specifically, the hydraulic system of the injection molding machine also includes an injection molding shell, and the injection molding screw 12 is partially inserted into the injection molding shell and forms a material cavity with the injection molding shell. Furthermore, a heater is provided on the periphery and / or inside of the injection molding shell, which can heat the material in the material cavity to form a molten material. Furthermore, a discharge port is provided on the injection molding shell at the front end of the injection molding screw 12 along the length direction, and the discharge port can be connected to the feed port of the mold so that the molten material can be transported into the mold. Among them, the specific structures of the injection molding shell and the mold belong to the prior art and will not be repeated here.

[0073] Specifically, the hydraulic system of the injection molding machine also includes a motor 13, which is connected to the injection molding screw 12 and can drive the injection molding screw 12 to rotate around its own central axis. The specific structure of the motor 13 connected to the injection molding screw 12 belongs to the prior art and will not be repeated here.

[0074] The first oil return control valve 22 is a two-position four-way pilot solenoid valve. The connecting port A1 of the first oil return control valve 22 is connected to the first pilot oil port G1 of the first oil return cartridge valve 21, the connecting port B1 of the first oil return control valve 22 is blocked, and the oil return port T1 of the first oil return control valve 22 is connected to the oil tank 92. When the first oil return control valve 22 is energized, the oil inlet P1 is connected to the connecting port B1, and the connecting port A1 is connected to the oil return port T1. When the first oil return control valve 22 is de-energized, the oil inlet P1 is connected to the connecting port A1, and the connecting port B1 is connected to the oil return port T1.

[0075] The second oil inlet control valve 32 is a two-position four-way pilot solenoid valve. The connecting port A2 of the second oil inlet control valve 32 is connected to the second pilot oil port G2 of the second oil inlet check valve 31, the connecting port B2 of the second oil inlet control valve 32 is blocked, and the oil return port T2 of the second oil inlet control valve 32 is connected to the oil tank 92. When the second oil inlet control valve 32 is energized, the oil inlet port P2 is connected to the connecting port B2, and the connecting port A2 is connected to the oil return port T2. When the second oil inlet control valve 32 is de-energized, the oil inlet port P2 is connected to the connecting port A2, and the connecting port B2 is connected to the oil return port T2.

[0076] Specifically, when a vacuum is generated in the first rodless chamber 113, the first oil return control valve 22 and the second oil inlet control valve 32 are both energized. The oil inlet port P1 is connected to the connecting port B1, the connecting port A1 is connected to the oil return port T1, and the pilot oil in the pilot oil chamber of the first oil return cartridge valve 21 flows through the first pilot oil port G1, the connecting port A1 and the oil return port T1 in turn back to the oil tank 92, and the oil inlet and outlet ports E1 and the oil inlet and outlet ports F1 are connected, so that the first rod chamber 112, the first oil return cartridge valve 21 and the first rodless chamber 113 are connected in turn, so that the hydraulic oil flowing out of the first rod chamber 112 directly replenishes the first rodless chamber 113. At the same time, the oil inlet P2 and the connecting port B2 are connected, the connecting port A2 and the oil return port T2 are connected, and the pilot oil in the pilot oil tank 92 of the second oil inlet check valve 31 flows through the second pilot oil port G2, the connecting port A2 and the oil return port T2 in sequence and returns to the oil tank 92, and the oil inlet E2 and the oil outlet F2 are connected, so that the first oil pump 91, the second oil inlet check valve 31 and the first rodless chamber 113 are connected in sequence, and the first oil pump 91 pumps the hydraulic oil in the oil tank 92 into the first rodless chamber 113 to replenish oil to the first rodless chamber 113.

[0077] Preferably, a back pressure proportional regulating valve 23 is provided on the pipeline connecting the oil return port T1 and the oil tank 92. By providing the back pressure proportional regulating valve 23 on the pipeline connecting the oil return port T1 and the oil tank 92, the opening of the back pressure proportional regulating valve 23 can be adaptively adjusted according to the particle size of the material to meet the demand of conveying the material during the electromelting process. Specifically, when the particles of the material are large, the gaps between the materials are large, and the opening of the back pressure proportional regulating valve 23 is adaptively increased. When the particles of the material are small, the gaps between the materials are small, and the opening of the back pressure proportional regulating valve 23 is adaptively reduced. Specifically, when the back pressure proportional regulating valve 23 is powered off, the opening of the back pressure proportional regulating valve 23 is maximum.

[0078] Preferably, in this embodiment, a first pressure sensor 101 is provided at the input end of the first rod chamber 112. The hydraulic oil pressure in the first rod chamber 112 is monitored in real time according to the first pressure sensor 101. The opening of the back pressure proportional regulating valve 23 is adjusted according to the hydraulic oil pressure in the first rod chamber 112. Specifically, when the hydraulic oil pressure in the first rod chamber 112 is greater than the set back pressure, the opening of the back pressure proportional regulating valve 23 is adjusted by feedback. So that the hydraulic oil pressure in the first rod chamber 112 is reduced to the set back pressure. When the hydraulic oil pressure in the first rod chamber 112 is less than the set back pressure, the opening of the back pressure proportional regulating valve 23 is adjusted by feedback. So that the hydraulic oil pressure in the first rod chamber 112 is increased to the set back pressure. Thereby ensuring that the monitoring value of the first pressure sensor 101 can always be consistent with the set back pressure. So as to further improve the working efficiency and working stability of the electromelt. It is understandable that for materials with different particle sizes and pore sizes, the corresponding set back pressure values ​​are different. The set back pressure is an empirical value obtained from a large number of previous tests.

[0079] Preferably, a second pressure sensor or a pressure gauge 102 is provided on the pipeline connecting the oil return port T1 and the back pressure proportional regulating valve 23, so as to further improve the accuracy of real-time monitoring of the hydraulic oil pressure in the first rod chamber 112. In this embodiment, a pressure gauge 102 is provided on the pipeline connecting the oil return port T1 and the back pressure proportional regulating valve 23 as an example.

[0080] Preferably, the hydraulic system of the injection molding machine further includes a first on-off valve 4 , which can selectively connect and disconnect the first rodless chamber 113 and the oil tank 92 .

[0081] Specifically, when a vacuum is generated in the first rodless chamber 113, the first rodless chamber 113 and the oil tank 92 are connected synchronously through the first on-off valve 4. Since a vacuum is generated in the first rodless chamber 113, the first rodless chamber 113 is in a negative pressure state. At this time, the first rodless chamber 113 and the oil tank 92 are connected through the first on-off valve 4, so that the hydraulic oil in the oil tank 92 can also be sucked into the first rodless chamber 113 to replenish the first rodless chamber 113. Therefore, in such a configuration, most of the hydraulic oil replenishing the first rodless chamber 113 comes from the first rod chamber 112, a small part of the hydraulic oil comes from the hydraulic oil pumped from the oil tank 92 to the first rodless chamber 113 by the first oil pump 91, and another small part comes from the hydraulic oil sucked from the oil tank 92 to the first rodless chamber 113 under negative pressure in the first rodless chamber 113, thereby effectively avoiding the influence caused by the vacuum generated in the first rodless chamber 113 during the electromelting process. Secondly, the first on-off valve 4 connects the first rodless chamber 113 and the oil tank 92, and can adjust the first rodless chamber 113 to maintain a relatively low and stable pressure, thereby further being able to reduce the pressure fluctuation caused by the oil replenishment to the first rodless chamber 113. Secondly, the first rodless chamber 113 and the oil tank 92 are connected through the first on-off valve 4. If too much hydraulic oil is replenished in the first rodless chamber 113, the excess hydraulic oil can directly flow back to the oil tank 92 through the first on-off valve 4, thereby further avoiding the phenomenon of excessive oil replenishment.

[0082] Specifically, in the present embodiment, the first on-off valve 4 is preferably a two-position four-way solenoid valve. The oil inlet P5 and the connecting port A5 of the first on-off valve 4 are both connected to the first rodless chamber 113, and the connecting port B5 and the oil return port T5 of the first on-off valve 4 are both connected to the oil tank 92. When the first on-off valve 4 is energized, the oil inlet P5 is connected to the connecting port B5, and the connecting port A5 is connected to the oil return port T5. When the first on-off valve 4 is de-energized, the oil inlet P5, the connecting port A5, the connecting port B5 and the oil return port T5 are all blocked. Therefore, when a vacuum is generated in the first rodless chamber 113, the first on-off valve 4 is synchronously controlled to be energized, so that the first on-off valve 4 connects the first rodless chamber 113 and the oil tank 92.

[0083] As an alternative, the first on-off valve 4 is a switch solenoid valve. When a vacuum is generated in the first rodless chamber 113 , the switch solenoid valve is controlled to connect the first rodless chamber 113 and the oil tank 92 .

[0084] Compared with using a switch solenoid valve as the first on-off valve 4, using a two-position four-way solenoid valve as the first on-off valve 4 can utilize its dual-channel principle to use a two-position four-way solenoid valve with a lower cost and a small diameter to achieve double the oil flow rate, thereby further improving the oil replenishment efficiency and reducing costs.

[0085] Optionally, in this embodiment, the connecting port A1 and the first pilot oil port G1 are also connected to the first rod chamber 112. Further, a mechanical one-way valve 24 is provided on the pipeline connecting the connecting port A1 and the first pilot oil port G1 to the first rod chamber 112, and the mechanical one-way valve 24 can guide the hydraulic oil in the first rod chamber 112 to flow unidirectionally to the connecting port A1 and the first pilot oil port G1. It can be understood that the first on-off valve 4 is energized so that the hydraulic oil sucked into the first rodless chamber 113 is used to fill the hydraulic oil that flows to the oil tank 92 from the mechanical one-way valve 24, the first oil return control valve 22 and the back pressure proportional control valve 23 in sequence.

[0086] Preferably, in the present embodiment, the first throttle valve 25 is also provided on the pipelines where the communication port A1 and the first pilot oil port G1 are both connected to the first rod chamber 112. The first throttle valve 25 can reduce the flow of the hydraulic oil flowing therethrough, so that when a vacuum is generated in the first rodless chamber 113, if the back pressure proportional regulating valve 23 is in an open state, the first throttle valve 25 can reduce the flow of the hydraulic oil therethrough, thereby effectively reducing the hydraulic oil that flows to the oil tank 92 from the first throttle valve 25, the first oil return control valve 22 and the back pressure proportional regulating valve 23 in sequence.

[0087] Preferably, in this embodiment, a third pressure sensor 103 is provided at the input end of the first rodless chamber 113. The third pressure sensor 103 can monitor the hydraulic oil pressure in the first rodless chamber 113 in real time.

[0088] Specifically, when the first on-off valve 4 is powered, the hydraulic oil pressure monitored by the third pressure sensor 103 is obtained in real time. It is determined whether the hydraulic oil pressure monitored by the third pressure sensor 103 is less than or equal to the set pressure. If the hydraulic oil pressure monitored by the third pressure sensor 103 is greater than the set pressure, an alarm is issued to remind that an abnormality has occurred in the electromelting process.

[0089] Among them, the hydraulic system of the injection molding machine also includes a first oil inlet combination valve, which includes a first oil inlet check valve 51 and a first oil inlet control valve 52. The oil inlet E3 of the first oil inlet check valve 51 and the oil inlet P3 of the first oil inlet control valve 52 are both connected to the output end of the first oil pump 91. The first oil inlet control valve 52 can selectively open and close the oil inlet E3 and the oil outlet F3 of the first oil inlet check valve 51. When the oil inlet E3 and the oil outlet F3 are connected, the first oil pump 91, the first oil inlet check valve 51 and the first rod chamber 112 are connected in sequence.

[0090] The second oil return combination valve includes a second oil return cartridge valve 61 and a second oil return control valve 62. The oil inlet P4 of the second oil return control valve 62 is connected to the output end of the first oil pump 91. The second oil return control valve 62 can selectively open and close the oil inlet and outlet E4 and the oil inlet and outlet F4 of the second oil return cartridge valve 61. When the oil inlet and outlet E4 and the oil inlet and outlet F4 are connected, the first rodless chamber 113, the second oil return cartridge valve 61 and the oil tank 92 are connected in sequence.

[0091] During injection, the first oil inlet control valve 52 is controlled to connect the oil inlet E3 and the oil outlet F3 of the first oil inlet check valve 51, so that the first oil pump 91, the first oil inlet check valve 51 and the first rod chamber 112 are connected in sequence, and hydraulic oil is delivered to the first rod chamber 112, pushing the first piston rod 111 to move axially from the first rod chamber 112 to the first rodless chamber 113, and pushing the injection screw 12 to squeeze the molten material in the material chamber to flow into the mold to achieve injection. At the same time, the second oil return control valve 62 is controlled to connect the oil inlet and outlet E4 and the oil inlet and outlet F4 of the second oil return cartridge valve 61, so that the first rodless chamber 113, the second oil return cartridge valve 61 and the oil tank 92 are connected in sequence, and the first piston rod 111 moves axially from the first rod chamber 112 to the first rodless chamber 113, while squeezing the hydraulic oil in the first rodless chamber 113, so that the hydraulic oil in the first rodless chamber 113 can smoothly return to the oil tank 92.

[0092] When loosening the injection screw 12, the second oil inlet control valve 32 is controlled to connect the oil inlet E2 and the oil outlet F2, so that the first oil pump 91, the second oil inlet check valve 31 and the first rodless chamber 113 are connected in sequence, and the first oil pump 91 pumps the hydraulic oil in the oil tank 92 into the first rodless chamber 113, pushing the first piston rod 111 to move axially from the first rodless chamber 113 to the first rod chamber 112, so as to realize the loosening of the injection screw 12. At the same time, the first oil return control valve 22 is controlled to connect the oil inlet and outlet E1 and the oil inlet and outlet F1, so that the first rod chamber 112, the first oil return cartridge valve 21 and the first rodless chamber 113 are connected in sequence, and a part of the hydraulic oil flowing out of the first rod chamber 112 flows into the first rodless chamber 113, and the remaining part flows through the mechanical one-way valve 24, the first oil return control valve 22 and the back pressure proportional regulating valve 23 and finally flows to the oil tank 92. In this process, the hydraulic oil flowing into the first rodless chamber 113 forms a differential high-speed loosening, which can effectively improve the efficiency of loosening the injection molding screw 12.

[0093] Specifically, the first oil inlet control valve 52 is a two-position four-way pilot solenoid valve. The connecting port A3 of the first oil inlet control valve 52 is connected to the third pilot oil port G3 of the first oil inlet check valve 51, the connecting port B3 of the first oil inlet control valve 52 is blocked, and the oil return port T3 of the first oil inlet control valve 52 is connected to the oil tank 92. When the first oil inlet control valve 52 is energized, the oil inlet port P3 is connected to the connecting port B3, and the connecting port A3 is connected to the oil return port T3. When the first oil inlet control valve 52 is de-energized, the oil inlet port P3 is connected to the connecting port A3, and the connecting port B3 is connected to the oil return port T3.

[0094] Specifically, the second oil return control valve 62 is a two-position four-way pilot solenoid valve. The connecting port A4 of the second oil return control valve 62 is connected to the fourth pilot oil port G4 of the second oil return cartridge valve 61, the connecting port B4 of the second oil return control valve 62 is blocked, and the oil return port T4 of the second oil return control valve 62 is connected to the oil tank 92. When the second oil return control valve 62 is energized, the oil inlet P4 is connected to the connecting port B4, and the connecting port A4 is connected to the oil return port T4. When the first oil return control valve 22 is de-energized, the oil inlet P4 is connected to the connecting port A4, and the connecting port B4 is connected to the oil return port T4.

[0095] Specifically, during injection, both the first oil inlet control valve 52 and the second oil return control valve 62 are energized. The oil inlet P3 is connected to the connecting port B3, the connecting port A3 is connected to the oil return port T3, and the pilot oil in the pilot oil chamber of the first oil inlet check valve 51 flows through the third pilot oil port G3, the connecting port A3 and the oil return port T3 in sequence to return to the oil tank 92, and the oil inlet E3 and the oil outlet F3 are connected, so that the first oil pump 91, the first oil inlet check valve 51 and the first rod chamber 112 are connected in sequence, so that the first oil pump 91 can deliver hydraulic oil to the first rod chamber 112, push the first piston rod 111 to move axially from the first rod chamber 112 to the first rodless chamber 113, and push the injection screw 12 to squeeze the molten material in the material chamber to flow into the mold, so as to achieve injection. At the same time, the oil inlet P4 is connected to the connecting port B4, and the connecting port A4 is connected to the oil return port T4, so that the first rodless chamber 113, the second oil return control valve 62 and the oil tank 92 are connected in sequence, and the first piston rod 111 moves axially from the first rod chamber 112 to the first rodless chamber 113 while squeezing the hydraulic oil in the first rodless chamber 113, so that the hydraulic oil in the first rodless chamber 113 can smoothly return to the oil tank 92. Further, at this time, it is also preferred to control the first on-off valve 4 to be energized. To further improve the efficiency of the hydraulic oil in the first rodless chamber 113 returning to the oil tank 92.

[0096] Specifically, when the injection screw 12 is loosened, the second oil inlet control valve 32 and the first oil return control valve 22 are both energized. The oil inlet port P2 is connected to the connecting port B2, and the connecting port A2 is connected to the oil return port T2, so that the first oil pump 91, the second oil inlet check valve 31 and the first rodless chamber 113 are connected in sequence, and the first oil pump 91 pumps the hydraulic oil in the oil tank 92 into the first rodless chamber 113, pushing the first piston rod 111 to move axially from the first rodless chamber 113 to the first rod chamber 112, so as to realize the loosening of the injection screw 12. At the same time, the oil inlet P1 is connected with the connecting port B1, and the connecting port A1 is connected with the oil return port T1, so that the first rod chamber 112, the first oil return cartridge valve 21 and the first rodless chamber 113 are connected in sequence, and a part of the hydraulic oil flowing out of the first rod chamber 112 flows into the first rodless chamber 113, and the remaining part flows through the mechanical one-way valve 24, the first oil return control valve 22 and the back pressure proportional regulating valve 23 and finally flows to the oil tank 92. In this process, the hydraulic oil flowing into the first rodless chamber 113 forms a differential high-speed loosening, which can effectively improve the efficiency of loosening the injection screw 12.

[0097] Preferably, the hydraulic system of the injection molding machine further includes a proportional reversing regulating valve 7. The proportional reversing regulating valve 7 can selectively connect the output end of the first oil pump 91 to the first rodless chamber 113, and the first rod chamber 112 to the oil tank 92. Or; connect the output end of the first oil pump 91 to the first rod chamber 112, and the first rodless chamber 113 to the oil tank 92. Or; disconnect the output end of the first oil pump 91, the oil tank 92, the first rod chamber 112, and the first rodless chamber 113 from each other.

[0098] Specifically, during injection, the first oil inlet control valve 52 and the second oil return control valve 62 are both powered. After the second set time, the first oil inlet control valve 52 and the second oil return control valve 62 are both powered off, and the proportional reversing regulating valve 7 is controlled so that the output end of the first oil pump 91 is connected to the first rod chamber 112, and the first rodless chamber 113 is connected to the oil tank 92. It can be understood that the hydraulic oil flow area of ​​the first oil inlet check valve 51 and the second oil return cartridge valve 61 is large, and the hydraulic oil flow area of ​​the proportional reversing regulating valve 7 is small and the flow area is adjustable. Therefore, before reaching the second set time, controlling the injection through the first oil inlet check valve 51 and the second oil return cartridge valve 61 can effectively improve the injection efficiency; after reaching the second set time, controlling the injection through the proportional reversing regulating valve 7 can accurately control the injection end position. Among them, the second set time is an empirical value obtained from a large number of previous tests, and the second set time is different for different products.

[0099] Specifically, when the injection screw 12 is loosened, the second oil inlet control valve 32 and the first oil return control valve 22 are both powered. After the first set time, the second oil inlet control valve 32 and the first oil return control valve 22 are both powered off, and the proportional reversing regulating valve 7 is controlled so that the output end of the first oil pump 91 is connected to the first rodless chamber 113, and the first rod chamber 112 is connected to the oil tank 92. It can be understood that the hydraulic oil flow area of ​​the second oil inlet check valve 31 and the first oil return cartridge valve 21 is large, and the hydraulic oil flow area of ​​the proportional reversing regulating valve 7 is small and the flow area is adjustable. Therefore, before reaching the first set time, the efficiency of loosening the injection screw 12 can be effectively improved by controlling the loosening of the injection screw 12 through the second oil inlet check valve 31 and the first oil return cartridge valve 21; after reaching the first set time, the loosening of the injection screw 12 can be accurately controlled by controlling the loosening of the injection screw 12 through the proportional reversing regulating valve 7. The first set time length is an empirical value obtained from a large number of previous tests, and the first set time length is different for different products.

[0100] Further, in the present embodiment, the proportional reversing regulating valve 7 is a three-position four-way proportional solenoid valve. The oil inlet P6 of the proportional reversing regulating valve 7 is connected to the output end of the first oil pump 91, the connecting port A6 of the proportional reversing regulating valve 7 is connected to the first rodless chamber 113, the connecting port B6 of the proportional reversing regulating valve 7 is connected to the first rod chamber 112, and the oil return port T6 of the proportional reversing regulating valve 7 is connected to the oil tank 92. When the left station of the proportional reversing regulating valve 7 is powered, the oil inlet P6 is connected to the connecting port A6, and the connecting port B6 is connected to the oil return port T6. When the right station of the proportional reversing regulating valve 7 is powered, the oil inlet P6 is connected to the connecting port B6, and the connecting port A6 is connected to the oil return port T6. When the proportional reversing regulating valve 7 is powered off, the oil inlet P6, the connecting port A6, the connecting port B6 and the oil return port T6 are all blocked.

[0101] Therefore, during injection, after the second set time, the right station of the proportional reversing regulating valve 7 is energized. When the injection screw 12 is loosened, after the first time, the left station of the proportional reversing regulating valve 7 is energized. When the electric melting glue is finished, the proportional reversing regulating valve 7 is de-energized. At this time, the proportional reversing regulating valve 7 blocks the first rod chamber 112 and the first rodless chamber 113 respectively to prepare for subsequent injection.

[0102] Optionally, the injection molding machine hydraulic system further includes a shuttle valve 120, one input end of the shuttle valve 120 is connected to the first oil pump 91, the other input end is connected to the first rod chamber 112, and the output end is connected to the oil inlet P3. When the first oil inlet control valve 52 is powered off and the first oil return control valve 22 is powered on, the hydraulic oil flowing out of the first rod chamber 112 and the hydraulic oil delivered by the first oil pump 91, whichever has a higher pressure, flows to the oil inlet P3, and finally flows to the third pilot oil port G3, disconnecting the oil inlet E3 and the oil outlet F3 of the first oil inlet check valve 51. To enhance the effect of disconnecting the oil inlet E3 and the oil outlet F3. In this embodiment, one input end of the shuttle valve 120 is connected to the first oil pump 91, and the other input end is connected to the pipeline connecting the first rod chamber 112 and the mechanical check valve 24.

[0103] Optionally, a second throttle valve 33 is provided on the pipeline connecting the communication port A2 and the first pilot oil port G2, so that the connection between the oil inlet E2 and the oil outlet F2 is smoother, and the disconnection between the oil inlet E2 and the oil outlet F2 is smoother.

[0104] Optionally, a third throttle valve 53 is provided on the pipeline connecting the communication port A3 and the first pilot oil port G3, so that the connection between the oil inlet E3 and the oil outlet F3 is smoother, and the disconnection between the oil inlet E3 and the oil outlet F3 is smoother.

[0105] Optionally, a fourth throttle valve 63 is provided on the pipeline connecting the communication port A4 and the first pilot oil port G4, so that the oil inlet and outlet E4 and the oil inlet and outlet F4 can be connected more smoothly, and the oil inlet and outlet E4 and the oil inlet and outlet F4 can be disconnected more smoothly.

[0106] Among them, the hydraulic system of the injection molding machine also includes a shot displacement cylinder 81, which includes a second cylinder body and a second piston rod 811 slidably arranged on the second cylinder body. The second piston rod 811 divides the second cylinder body into a second rod chamber 812 and a second rodless chamber 813. One end of the second piston rod 811 extending out of the second cylinder body is connected to the mold transmission and can drive the mold to press against the nozzle 131, so that the nozzle 131 can connect the feed port of the mold and the discharge port of the injection molding shell.

[0107] Among them, the hydraulic system of the injection molding machine also includes a first reversing regulating valve 82 and a pressure-maintaining valve 83. The first reversing regulating valve 82 can selectively connect the output end of the first oil pump 91 with the oil inlet E5 of the pressure-maintaining valve 83, and the second rodless chamber 813 with the oil tank 92; or, connect the output end of the first oil pump 91 with the second rodless chamber 813, and the oil inlet E5 of the pressure-maintaining valve 83 with the oil tank 92; or, the oil inlet E5 of the pressure-maintaining valve 83 is connected with the oil tank 92, and the second rodless chamber 813 is closed. The oil outlet F5 of the pressure-maintaining valve 83 is connected with the second rod chamber 812. The pressure-maintaining valve 83 can selectively make the oil inlet E5 and the oil outlet F5 interconnected; or, the oil inlet E5 and the oil outlet F5 are unidirectionally connected.

[0108] Specifically, when the mold is pressed against the nozzle 131, the output end of the first oil pump 91 is controlled to be connected to the oil inlet E5 of the pressure-maintaining valve 83, and the second rodless chamber 813 is connected to the oil tank 92. The oil inlet E5 and the oil outlet F5 are controlled to be interconnected, or the oil inlet E5 and the oil outlet F5 are connected in one direction. Hydraulic oil is delivered to the second rod chamber 812 to drive the second piston rod 811 to move, and the mold is driven to move synchronously. Until the mold is pressed against the nozzle 131, the nozzle 131 is connected to the feed inlet of the mold and the discharge outlet of the injection molding shell.

[0109] Specifically, when the mold is pressed against the nozzle 131, so that the nozzle 131 is connected to the feed port of the mold and the discharge port of the injection molding shell, the oil inlet E5 and the oil outlet F5 are controlled to be connected in one direction, the oil inlet E5 of the pressure-maintaining valve 83 is controlled to be connected to the oil tank 92, and the second rodless cavity 813 is closed, so that the mold is kept pressed against the nozzle 131, so as to facilitate the subsequent injection.

[0110] Specifically, when the mold is to be moved away from the nozzle 131, the output end of the first oil pump 91 is controlled to be connected to the second rodless chamber 813, and the oil inlet E5 of the pressure-maintaining valve 83 is connected to the oil tank 92. The oil inlet E5 and the oil outlet F5 are controlled to be interconnected. The hydraulic oil delivered to the second rodless chamber 813 pushes the second piston rod 811 axially from the second rodless chamber 813 to the second rod chamber 812, and simultaneously squeezes the hydraulic oil in the second rod chamber 812 to flow into the oil tank 92. This is to achieve pushing the mold away from the nozzle 131.

[0111] Specifically, when the hydraulic system of the injection molding machine fails and needs maintenance, the power is cut off, the oil inlet E5 and the oil outlet F5 are connected, and the oil inlet E5 of the pressure-maintaining valve 83 is connected to the oil tank 92, so that the high-pressure hydraulic oil in the second rod chamber 812 can flow to the oil tank 92 to release pressure.

[0112] Specifically, in this embodiment, taking the example that the number of the shooting cylinders 81 is two, the two shooting cylinders 81 are distributed in parallel.

[0113] Specifically, in this embodiment, the first reversing regulating valve 82 is a three-position four-way solenoid valve. The oil inlet P7 of the first reversing regulating valve 82 is connected to the output end of the first oil pump 91, the connecting port A7 of the first reversing regulating valve 82 is connected to the oil inlet E5, the connecting port B7 of the first reversing regulating valve 82 is connected to the second rodless chamber 813, and the oil return port T7 of the first reversing regulating valve 82 is connected to the oil tank 92. When the left station of the first reversing regulating valve 82 is powered, the oil inlet P7 is connected to the connecting port B7, and the connecting port A7 is connected to the oil return port T7. When the right station of the first reversing regulating valve 82 is powered, the oil inlet P7 is connected to the connecting port A7, and the connecting port B7 is connected to the oil return port T7. When the first reversing regulating valve 82 is powered off, the connecting port A7 is connected to the oil return port T7, the connecting port B7 is blocked, and the oil inlet P7 is blocked.

[0114] Specifically, in this embodiment, when the pressure-maintaining valve 83 is powered, the oil inlet E5 and the oil outlet F5 are in one-way communication. When the pressure-maintaining valve 83 is powered off, the oil inlet E5 and the oil outlet F5 are in mutual communication.

[0115] Therefore, when the mold is pressed against the nozzle 131, the right station of the first reversing regulating valve 82 is controlled to be energized, and the pressure-maintaining valve 83 is controlled to be energized or de-energized. When the mold is pressed against the nozzle 131 so that the nozzle 131 is connected to the feed port of the mold and the discharge port of the injection molding shell, the first reversing regulating valve 82 is controlled to be de-energized, and the pressure-maintaining valve 83 is controlled to be energized. When the mold is moved away from the nozzle 131, the left station of the first reversing regulating valve 82 is controlled to be energized, and the pressure-maintaining valve 83 is controlled to be de-energized. When the hydraulic system of the injection molding machine fails and needs maintenance, the first reversing regulating valve 82 and the pressure-maintaining valve 83 are both de-energized, and the high-pressure hydraulic oil in the second rod chamber 812 can flow to the oil tank 92 to release pressure.

[0116] Optionally, a fourth pressure sensor 104 is provided at the input end of the second rod chamber 812. It is convenient to monitor the pressure of the hydraulic oil in the second rod chamber 812. Specifically, when the mold is pressed against the nozzle 131, it is determined in real time whether the pressure of the hydraulic oil in the second rod chamber 812 obtained by monitoring is less than the set holding pressure. If the pressure of the hydraulic oil in the second rod chamber 812 is less than the set holding pressure, the right station of the first reversing regulating valve 82 is controlled to be energized to deliver hydraulic oil to the second rodless chamber 813. Until the pressure of the hydraulic oil in the second rod chamber 812 is greater than or equal to the set holding pressure.

[0117] The hydraulic system of the injection molding machine further includes a nozzle cylinder 130 and a nozzle 131. The nozzle cylinder 130 includes a third cylinder body and a third piston rod slidably disposed in the third cylinder body. The third piston rod divides the third cylinder body into a third rod chamber and a third rodless chamber. One end of the third piston rod extending out of the third cylinder body is transmission-connected to the nozzle 131 and can drive the nozzle 131 to connect the discharge port of the injection molding shell and the feed port of the mold. The hydraulic system of the injection molding machine further includes a second reversing regulating valve 132. The second reversing regulating valve 132 can selectively connect one of the third rod chamber and the third rodless chamber to the output end of the first oil pump 91, and the other to the oil tank 92.

[0118] Specifically, when the discharge port and the feed port are to be connected through the nozzle 131, the third rodless chamber is controlled to be connected to the output end of the first oil pump 91, and the third rod chamber is connected to the oil tank 92. Hydraulic oil is delivered to the third rodless chamber to push the third piston rod to move, drive the nozzle 131 to move to connect the discharge port and the feed port, and simultaneously squeeze the hydraulic oil in the third rod chamber to flow to the oil tank 92. In this way, the nozzle 131 is connected to the discharge port and the feed port.

[0119] Specifically, when the discharge port and the feed port are to be disconnected through the nozzle 131, the third rod chamber is controlled to be connected to the output end of the first oil pump 91, and the third rodless chamber is connected to the oil tank 92. Hydraulic oil is delivered to the third rodless chamber to push the third piston rod to move, drive the moving end of the nozzle 131 to disconnect the discharge port and the feed port, and simultaneously squeeze the hydraulic oil in the third rodless chamber to flow to the oil tank 92. In this way, the nozzle 131 disconnects the discharge port and the feed port.

[0120] Specifically, in the present embodiment, the second reversing regulating valve 132 is a two-position four-way solenoid valve. The oil inlet P8 of the second reversing regulating valve 132 is connected to the output end of the first oil pump 91, the connecting port A8 of the second reversing regulating valve 132 is connected to the third rodless chamber, the connecting port B8 of the second reversing regulating valve 132 is connected to the third rod chamber, and the oil return port T8 of the second reversing regulating valve 132 is connected to the oil tank 92. When the second reversing regulating valve 132 is powered on, the oil inlet P8 is connected to the connecting port B8, and the connecting port A8 is connected to the oil return port T8. When the second reversing regulating valve 132 is powered off, the oil inlet P8 is connected to the connecting port A8, and the connecting port B8 is connected to the oil return port T8.

[0121] Therefore, when the discharge port and the feed port are to be connected through the nozzle 131, the second reversing regulating valve 132 is controlled to be powered off. When the discharge port and the feed port are to be disconnected through the nozzle 131, the second reversing regulating valve 132 is controlled to be powered.

[0122] It is understandable that the process of the nozzle 131 connecting the discharge port and the feed port, and the process of the mold abutting against the nozzle 131 can be performed simultaneously, so as to further improve the injection molding efficiency.

[0123] Optionally, the hydraulic system of the injection molding machine further includes a second on-off valve 93 and a second oil pump 94, the input end of the second oil pump 94 is connected to the oil tank 92, the output end of the second oil pump 94 is connected to the oil inlet P9 of the second on-off valve 93, the connecting port A9 of the second on-off valve 93 is blocked, the connecting port B9 of the second on-off valve 93 is connected to the output end of the first oil pump 91, and the oil return port T9 of the second on-off valve 93 is connected to the oil tank 92. When the second on-off valve 93 is energized, the oil inlet P9 is connected to the connecting port B9, and the connecting port A9 is connected to the oil return port T9. When the second on-off valve 93 is de-energized, the oil inlet P9, the connecting port A9, the connecting port B9 and the oil return port T9 are all blocked. It can be understood that when the second on-off valve 93 is energized, the output end of the first oil pump 91 is connected to the output end of the second oil pump 94, so that the first oil pump 91 and the second oil pump 94 can pump hydraulic oil at the same time.

[0124] In particular, when the process of the nozzle 131 connecting the discharge port and the feed port, and the process of the mold abutting against the nozzle 131 can be carried out simultaneously, more hydraulic oil is required, and the first oil pump 91 and the second oil pump 94 can be used to pump the hydraulic oil together. Secondly, when injecting glue and loosening the injection screw 12, if a larger flow of hydraulic oil is needed, the first oil pump 91 and the second oil pump 94 can also be used to pump the hydraulic oil together.

[0125] Optionally, the hydraulic system of the injection molding machine further includes a clamping system 140, and the oil inlet end of the clamping system 140 is connected to the pipeline connected to the second oil pump 94 and the oil inlet P9, so that hydraulic oil can also be delivered to the clamping system 140 through the second oil pump 94. The specific structure of the clamping system 140 belongs to the prior art and will not be described in detail here.

[0126] The present invention also provides an injection molding machine hydraulic control method, which is used to be implemented in the above-mentioned injection molding machine hydraulic system.

[0127] like Figure 2 As shown, the hydraulic control method of the injection molding machine includes:

[0128] During the electromelting process, whether a vacuum is generated in the first rodless chamber 113 is determined according to the moving direction and the moving amount of the first piston rod 111 .

[0129] If the first rodless chamber 113 generates a vacuum, the first oil return control valve 22 is controlled to connect the oil inlet and outlet E1 with the oil inlet and outlet F1; the second oil inlet control valve 32 is synchronously controlled to connect the oil inlet E2 with the oil outlet F2; the oil replenishment voltage is synchronously calculated and the voltage of the first oil pump 91 is adjusted to the oil replenishment voltage.

[0130] Specifically, the change in the distance moved by the injection molding screw 12 in the axial direction from the first rodless cavity 113 to the first rod cavity 112 is monitored by the electronic ruler 14. If the change in the distance moved by the injection molding screw 12 in the axial direction from the first rodless cavity 113 to the first rod cavity 112 is greater than the set value, the first rodless cavity 113 generates a vacuum. The set value is an empirical value obtained from a large number of previous tests. In this embodiment, the exemplary set value is set to zero.

[0131] Specifically, the calculation formula of the oil replenishment voltage is:

[0132] V(t)=△L / △t;

[0133] Q(t)=π*r*r*V(t) / 2;

[0134] n(t)=Q(t) / V(row);

[0135] U(t)=n(t)*60*set voltage value / N;

[0136] Wherein, △L is the change in the distance of the injection molding screw 12 moving axially from the first rodless cavity 113 to the first rod cavity 112, mm. △t is the time change of moving △L, s. V(t) is the ratio of the change in the distance of the injection molding screw 12 moving axially from the first rodless cavity 113 to the first rod cavity 112 to the time change, mm / s. r is the radius of the first piston rod 111, mm. Q(t) is the total required oil replenishment amount of the first rodless cavity 113, mm 3 / s. V(displacement) is the displacement of the first oil pump 91, mm 3 / r. n(t) is the number of revolutions required by the first oil pump 91 per second, r / s. N is the maximum rated number of revolutions per minute of the first oil pump 91 under the set voltage value, r / min. The set voltage value is a value less than or equal to the maximum allowable voltage value of the first oil pump 91.

[0137] Preferably, when a vacuum is generated in the first rodless chamber 113, the first rodless chamber 113 and the oil tank 92 are connected synchronously through the first on-off valve 4. Since a vacuum is generated in the first rodless chamber 113, the first rodless chamber 113 is in a negative pressure state. At this time, the first rodless chamber 113 and the oil tank 92 are connected through the first on-off valve 4, so that the hydraulic oil in the oil tank 92 can also be sucked into the first rodless chamber 113, and the first rodless chamber 113 is replenished with oil. Therefore, it is configured in this way that most of the hydraulic oil replenished into the first rodless chamber 113 comes from the first rod chamber 112, a small part of the hydraulic oil comes from the hydraulic oil pumped from the oil tank 92 to the first rodless chamber 113 by the first oil pump 91, and another small part comes from the hydraulic oil sucked into the first rodless chamber 113 from the oil tank 92 at a negative pressure in the first rodless chamber 113, thereby effectively avoiding the influence caused by the vacuum generated in the first rodless chamber 113 during the electromelting process. Secondly, the first on-off valve 4 connects the first rodless chamber 113 and the oil tank 92, and can adjust the first rodless chamber 113 to maintain a relatively low and stable pressure, thereby further being able to reduce the pressure fluctuation caused by the oil replenishment to the first rodless chamber 113. Secondly, the first rodless chamber 113 and the oil tank 92 are connected through the first on-off valve 4. If too much hydraulic oil is replenished in the first rodless chamber 113, the excess hydraulic oil can directly flow back to the oil tank 92 through the first on-off valve 4, thereby further avoiding the phenomenon of excessive oil replenishment.

[0138] Thereby, the impact of the vacuum generated in the first rodless cavity 113 can be effectively reduced during the electric melt process, and the injection molding cycle can be effectively shortened; secondly, the pressure fluctuation caused by the oil replenishment to the first rodless cavity 113 by the first oil pump 91 can be effectively reduced, and the stability of the quality of the product obtained by injection molding can be effectively guaranteed, and the energy consumption caused by the first oil pump 91 replenishing oil to the first rodless cavity 113 can be effectively reduced; secondly, the amount of oil replenished to the first rodless cavity 113 by the first oil pump 91 can be accurately controlled, and excessive oil replenishment can be effectively avoided.

[0139] like Figure 3 As shown, the injection molding machine hydraulic control method also includes:

[0140] When the injection screw 12 is loosened, the first oil return control valve 22 is controlled to connect the oil inlet and outlet E1 with the oil inlet and outlet F1; the second oil inlet control valve 32 is synchronously controlled to connect the oil inlet E2 with the oil outlet F2, and the first oil pump 91 pumps oil to the oil inlet E2; the back pressure proportional regulating valve 23 is synchronously controlled to cut off the power.

[0141] After the first set time, the first oil return control valve 22 is controlled to disconnect the oil inlet and outlet E1 and the oil inlet and outlet F1; the second oil inlet control valve 32 is synchronously controlled to disconnect the oil inlet E2 and the oil outlet F2; the proportional reversing regulating valve 7 is synchronously controlled to connect the output end of the first oil pump 91 and the first rodless chamber 113, and the first rod chamber 112 and the oil tank 92 are connected, and the first oil pump 91 pumps oil to the first rodless chamber 113.

[0142] Since the hydraulic oil flow area of ​​the second oil inlet check valve 31 and the first oil return cartridge valve 21 is large, and the hydraulic oil flow area of ​​the proportional reversing regulating valve 7 is small and the flow area is adjustable, such a configuration can effectively improve the efficiency of the injection screw 12 by controlling the loosening and retracting of the injection screw 12 before reaching the first set time; after reaching the first set time, the injection screw 12 is controlled by the proportional reversing regulating valve 7 to accurately control the end position of the loosening and retracting.

[0143] like Figure 4 As shown, the injection molding machine hydraulic control method also includes:

[0144] During injection, the first oil inlet control valve 52 and the second oil return control valve 62 are both powered, and the first oil pump 91 pumps oil to the oil inlet E3. After the second set time, the first oil inlet control valve 52 and the second oil return control valve 62 are both powered off, and the proportional reversing regulating valve 7 is controlled so that the output end of the first oil pump 91 is connected to the first rod chamber 112, and the first rodless chamber 113 is connected to the oil tank 92, and the first oil pump 91 pumps oil to the first rod chamber 112.

[0145] Since the hydraulic oil flow area of ​​the first oil inlet check valve 51 and the second oil return cartridge valve 61 is large, and the hydraulic oil flow area of ​​the proportional reversing regulating valve 7 is small and the flow area is adjustable, before the second set time is reached, the injection is controlled by the first oil inlet check valve 51 and the second oil return cartridge valve 61, which can effectively improve the injection efficiency; after the second set time is reached, the injection is controlled by the proportional reversing regulating valve 7, which can accurately control the injection end position.

[0146] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A hydraulic system for an injection molding machine, comprising an injection cylinder (11), wherein the injection cylinder (11) comprises a first cylinder body and a first piston rod (111) slidably arranged on the first cylinder body, wherein the first piston rod (111) divides the first cylinder body into a first rod chamber (112) and a first rodless chamber (113); one end of the first piston rod (111) extending out of the first cylinder body is transmission-connected to an injection screw (12) and can drive the injection screw (12) to move along its own axial direction; characterized in that: The injection molding machine hydraulic system also includes: The first oil return combination valve comprises a first oil return cartridge valve (21) and a first oil return control valve (22); the oil inlet P1 of the first oil return control valve (22) is connected to the output end of the first oil pump (91), and the input end of the first oil pump (91) is connected to the oil tank (92); the first oil return control valve (22) can selectively open and close the oil inlet and outlet E1 and the oil inlet and outlet F1 of the first oil return cartridge valve (21); when the oil inlet and outlet E1 and the oil inlet and outlet F1 are connected, the first rod chamber (112), the first oil return cartridge valve (21) and the first rodless chamber (113) are connected in sequence; the first oil return control valve (22) ) is a two-position four-way pilot solenoid valve, the communication port A1 of the first oil return control valve (22) is connected to the first pilot oil port G1 of the first oil return cartridge valve (21), the communication port B1 of the first oil return control valve (22) is blocked, and the oil return port T1 of the first oil return control valve (22) is connected to the oil tank (92); when the first oil return control valve (22) is energized, the oil inlet P1 is connected to the communication port B1, and the communication port A1 is connected to the oil return port T1; when the first oil return control valve (22) is de-energized, the oil inlet P1 is connected to the communication port A1, and the communication port B1 is connected to the oil return port T1; A second oil inlet combination valve comprises a second oil inlet check valve (31) and a second oil inlet control valve (32), wherein the oil inlet port E2 of the second oil inlet check valve (31) and the oil inlet port P2 of the second oil inlet control valve (32) are both connected to the output end of the first oil pump (91), and the second oil inlet control valve (32) can selectively open and close the oil inlet port E2 and the oil outlet port F2 of the second oil inlet check valve (31), and when the oil inlet port E2 and the oil outlet port F2 are connected, the first oil pump (91), the second oil inlet check valve (31) and the first rodless chamber (113) are connected in sequence; A first oil inlet combination valve comprises a first oil inlet check valve (51) and a first oil inlet control valve (52); an oil inlet port E3 of the first oil inlet check valve (51) and an oil inlet port P3 of the first oil inlet control valve (52) are both connected to an output end of the first oil pump (91); the first oil inlet control valve (52) can selectively open and close the oil inlet port E3 and the oil outlet port F3 of the first oil inlet check valve (51); when the oil inlet port E3 and the oil outlet port F3 are connected, the first oil pump (91), the first oil inlet check valve (51) and the first rod chamber (112) are connected in sequence; The second oil return combination valve comprises a second oil return cartridge valve (61) and a second oil return control valve (62); the oil inlet P4 of the second oil return control valve (62) is connected to the output end of the first oil pump (91); the second oil return control valve (62) can selectively open and close the oil inlet and outlet E4 and the oil inlet and outlet F4 of the second oil return cartridge valve (61); when the oil inlet and outlet E4 and the oil inlet and outlet F4 are connected, the first rodless chamber (113), the second oil return cartridge valve (61) and the oil tank (92) are connected in sequence.

2. The hydraulic system of the injection molding machine according to claim 1, characterized in that: The injection molding machine hydraulic system further comprises a first on-off valve (4), wherein the first on-off valve (4) can selectively open and close the first rodless chamber (113) and the oil tank (92).

3. The hydraulic system of the injection molding machine according to claim 1, characterized in that: The injection molding machine hydraulic system also includes a proportional reversing regulating valve (7); the proportional reversing regulating valve (7) can selectively connect the output end of the first oil pump (91) with the first rodless chamber (113), and the first rod chamber (112) with the oil tank (92); or, connect the output end of the first oil pump (91) with the first rod chamber (112), and the first rodless chamber (113) with the oil tank (92); or, disconnect the output end of the first oil pump (91), the oil tank (92), the first rod chamber (112) and the first rodless chamber (113) from each other.

4. The hydraulic system for an injection molding machine according to claim 1, characterized in that: The injection molding machine hydraulic system also includes a shot displacement oil cylinder (81), the shot displacement oil cylinder (81) includes a second cylinder body and a second piston rod (811) slidably arranged on the second cylinder body, the second piston rod (811) divides the second cylinder body into a second rod chamber (812) and a second rodless chamber (813), one end of the second piston rod (811) extending out of the second cylinder body is transmission-connected to the mold and can drive the mold to press against the nozzle (131), so that the nozzle (131) can communicate with the feed port of the mold and the discharge port of the injection molding shell; The injection molding machine hydraulic system also includes a first reversing regulating valve (82) and a pressure-maintaining valve (83), wherein the first reversing regulating valve (82) can selectively connect the output end of the first oil pump (91) with the oil inlet E5 of the pressure-maintaining valve (83), and connect the second rodless chamber (813) with the oil tank (92); or connect the output end of the first oil pump (91) with the second rodless chamber (813), and connect the oil inlet E5 of the pressure-maintaining valve (83) with the oil tank (92); or connect the oil inlet E5 of the pressure-maintaining valve (83) with the oil tank (92), and the second rodless chamber (813) is closed; The oil outlet F5 of the pressure-maintaining valve (83) is in communication with the second rod chamber (812); The pressure-maintaining valve (83) can selectively enable the oil inlet E5 and the oil outlet F5 to communicate with each other; or, the oil inlet E5 and the oil outlet F5 can be unidirectionally communicated.

5. The hydraulic control method of an injection molding machine is characterized in that: Used to implement the hydraulic system of an injection molding machine according to any one of claims 1 to 4, the hydraulic control method of the injection molding machine comprises: During the electromelting process, determining whether the first rodless chamber (113) generates a vacuum according to the moving direction of the first piston rod (111) and the moving amount of the first piston rod (111); If the first rodless chamber (113) generates a vacuum, the first oil return control valve (22) is controlled to connect the oil inlet and outlet E1 with the oil inlet and outlet F1; the second oil inlet control valve (32) is synchronously controlled to connect the oil inlet E2 with the oil outlet F2; the oil replenishment voltage is synchronously calculated and the voltage of the first oil pump (91) is adjusted to the oil replenishment voltage.

6. The method for hydraulic control of an injection molding machine according to claim 5, characterized in that: The calculation formula for calculating the oil replenishment voltage U(t) is: Q(t)=π*r*r*V(t) / 2; n(t)=Q(t) / V(row); U(t)=n(t)*60*set voltage value / N; Wherein, r is the radius of the first piston rod (111), mm; V(t) is the ratio of the movement change of the injection screw (12) to the time change of the electric melt glue, mm / s; Q(t) is the total required oil replenishment amount of the first rodless chamber (113), mm 3 / s; V(displacement) is the displacement of the first oil pump (91), mm 3 / r; n(t) is the number of revolutions required for the first oil pump (91) per second, r / s; N is the maximum rated number of revolutions per minute of the first oil pump (91) at a set voltage value, r / min.

7. The method for hydraulic control of an injection molding machine according to claim 5, characterized in that: The injection molding machine hydraulic system further comprises a first on-off valve (4), wherein the first on-off valve (4) can selectively connect and disconnect the first rodless chamber (113) and the oil tank (92); If the first rodless chamber (113) generates a vacuum, the first on-off valve (4) is synchronously controlled to connect the first rodless chamber (113) and the oil tank (92).

8. The method for hydraulic control of an injection molding machine according to claim 5, characterized in that: A back pressure proportional regulating valve (23) is provided on a pipeline connecting the oil return port T1 of the first oil return control valve (22) and the oil tank (92); the injection molding machine hydraulic system further comprises a proportional reversing regulating valve (7), the proportional reversing regulating valve (7) can selectively connect the output end of the first oil pump (91) and the first rodless chamber (113), and the first rod chamber (112) and the oil tank (92); The injection molding machine hydraulic control method also includes: When the injection screw (12) is loosened, the first oil return control valve (22) is controlled to connect the oil inlet and outlet E1 with the oil inlet and outlet F1; the second oil inlet control valve (32) is synchronously controlled to connect the oil inlet E2 with the oil outlet F2, and the first oil pump (91) pumps oil to the oil inlet E2; and the back pressure proportional regulating valve (23) is synchronously controlled to be powered off; After the first set time, the first oil return control valve (22) is controlled to disconnect the oil inlet and outlet E1 and the oil inlet and outlet F1; the second oil inlet control valve (32) is synchronously controlled to disconnect the oil inlet E2 and the oil outlet F2; the proportional reversing regulating valve (7) is synchronously controlled to connect the output end of the first oil pump (91) and the first rodless chamber (113), and the first rod chamber (112) and the oil tank (92), and the first oil pump (91) pumps oil into the first rodless chamber (113).

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