Die opening and closing hydraulic loop of injection molding machine and injection molding machine system

Abstract

The invention discloses an injection molding machine mold opening and closing hydraulic loop and an injection molding machine system. The mold opening and closing hydraulic loop of the injection molding machine comprises a working oil cylinder and a proportional valve, and the working oil cylinder can be controlled to execute different actions by adjusting the proportional valve to different working states so as to control mold opening, mold closing and differential mold closing of the injection molding machine. According to the differential proportional valve with the flow regeneration function, on the premise that all functions of mold opening and closing are achieved, the control precision in the mold opening and closing process can be effectively improved, energy consumption is reduced, the number of parts of a compression system is reduced, and the occupied space of the system is saved.

Description

Technical Field

[0001] The invention relates to the field of hydraulic technology, and in particular to a mold opening and closing hydraulic circuit of an injection molding machine, and an injection molding machine system provided with the hydraulic circuit. Background Art

[0002] See also Figure 1 In the existing hydraulic circuit for opening and closing molds of a medium-sized injection molding machine, in addition to the pressure oil supply end P, the return oil end T, and the mold closing oil cylinder 01, a first reversing valve 03 (three-position four-way solenoid valve), a second reversing valve 02, a brake valve 04, a safety valve 05, and a safety door 06 are also provided. The detection part 051 of the safety valve 05 is linked with the safety door 06 of the equipment. Only when the safety door 06 is completely closed, the main valve part 052 of the safety valve 05 can be opened. Among them, the flow regeneration in the mold closing process can be achieved through the second reversing valve 02 and the intermediate oil circuit 021 connected thereto, thereby improving the mold closing speed; the brake valve 04 can make the moving plate stop accurately when it needs to stop moving. The brake valve 04 is composed of a cartridge valve 041 and a third reversing valve 042. Different dampings are provided in different flow channels of the third reversing valve 042. Different sizes of return oil back pressures are generated by controlling the third reversing valve 042, thereby obtaining different braking effects.

[0003] The hydraulic circuit for opening and closing the mold of the medium-sized injection molding machine has the following defects:

[0004] 1) In order to complete the mold opening and closing action, it is necessary to configure a first reversing valve 03 for controlling the mold opening and closing, a brake valve 04, a second reversing valve 02 for realizing differential mold closing and the intermediate oil circuit 021 connected thereto. It can be seen that the number of valve parts is large, the pipeline connection is relatively complex, the cost is high, and the first reversing valve 03 and the brake valve 04 need to be accurately matched. The reversing valve 03 and the brake valve 04 are both in place at one time and cannot be adjusted by electrical signals. Therefore, the debugging is difficult and the mold opening and closing accuracy is relatively poor. In addition, the tooling for installing three valves is large, and the machine occupies a large space.

[0005] 2) The mold opening action of the injection molding machine is a slow (mold opening and breaking section) - fast (middle fast section) - slow (final braking section). The ideal situation is that there is no braking effect in the fast section, and braking only in the slow section. However, since the return oil passes through the brake valve 04 and then returns to the oil tank, the braking effect is controlled by the third reversing valve 042, and the third reversing valve 042 has only two states for braking control: light braking when power is not available and heavy braking when power is available. Therefore, there is actually an obvious braking effect in the fast section, which reduces the mold opening speed and increases energy consumption.

[0006] 3) This type of braking principle is applied to many models, so different models need to be tested accordingly. The ideal braking effect must be obtained by replacing the damping in the flow channel of the third reversing valve 042. This is more troublesome and it is difficult to achieve the best actual braking effect.

[0007] Therefore, how to optimize the hydraulic circuit for opening and closing the mold of an injection molding machine is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0008] In view of this, the object of the present invention is to provide an injection molding machine system and its mold opening and closing hydraulic circuit, which can effectively improve the control accuracy in the mold opening and closing process, reduce energy consumption, compress the number of system parts, and save system space while realizing all the functions of mold opening and closing through a differential proportional valve with flow regeneration function.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A mold opening and closing hydraulic circuit for an injection molding machine comprises a working oil cylinder and a proportional valve. By adjusting the proportional valve to different working states, the working oil cylinder can be controlled to perform different actions to control the mold opening, mold closing and differential mold closing of the injection molding machine.

[0011] Optionally, in the above-mentioned hydraulic circuit for opening and closing the mold of the injection molding machine, the first working oil port and the second working oil port of the proportional valve are connected to the first cavity and the second cavity of the working oil cylinder through the first connecting oil circuit and the second connecting oil circuit respectively; the oil inlet and the oil return port of the proportional valve are connected to the oil inlet circuit and the oil return circuit respectively;

[0012] When the proportional valve is in the first working state, the first connecting oil circuit is connected to the oil inlet circuit through the proportional valve, the second connecting oil circuit is connected to the oil return circuit through the proportional valve, and the working oil cylinder controls the injection molding machine to open the mold;

[0013] When the proportional valve is in the second working state, the first connecting oil circuit and the second connecting oil circuit are connected through the proportional valve, and the working oil cylinder controls the differential mold clamping of the injection molding machine;

[0014] When the proportional valve is in the third working state, the first connecting oil circuit is connected to the oil return oil circuit through the proportional valve, the second connecting oil circuit is connected to the oil inlet oil circuit through the proportional valve, and the working oil cylinder controls the mold closing and compacting of the injection molding machine.

[0015] Optionally, in the above-mentioned injection molding machine mold opening and closing hydraulic circuit, when the proportional valve is in the fourth working state, the first working oil port, the second working oil port, the oil inlet port, and the oil return port are interconnected. The fourth working state is a transition state between the second working state and the third working state, that is, a transition position; or, the fourth working state is a working position of the proportional valve, that is, the proportional valve also has an H-type middle position function.

[0016] Optionally, in the above-mentioned injection molding machine mold opening and closing hydraulic circuit, the proportional valve includes a valve body, a valve core and a driving device;

[0017] The valve body is provided with the first working oil port, the second working oil port, the oil inlet port, and the oil return port;

[0018] The valve core is relatively movably arranged in the valve body, and is used to control the connection and isolation between different oil ports;

[0019] The driving device is used to control the movement of the valve core.

[0020] Optionally, in the above-mentioned hydraulic circuit for opening and closing the mold of the injection molding machine, the valve body is provided with:

[0021] a first oil passage, communicating with the oil return port to connect to the oil return circuit;

[0022] a second oil passage, communicating with the oil inlet so as to be connected to the oil inlet circuit;

[0023] a third oil passage, communicating with the first working oil port to connect to the first connecting oil circuit;

[0024] The fourth oil passage is communicated with the second working oil port to be connected to the second connecting oil circuit.

[0025] Optionally, in the above-mentioned injection molding machine mold opening and closing hydraulic circuit, the side wall of the valve core is provided with a first groove, a second groove, a third groove, a fourth groove, and a fifth groove;

[0026] When the proportional valve is in the first working state, the second oil passage is connected to the third oil passage through the third groove, and the fourth oil passage is connected to the first oil passage through the first groove;

[0027] When the proportional valve is in the second working state, the second oil passage and the fourth oil passage are communicated through the second groove, and the second oil passage and the third oil passage are communicated through the fifth groove;

[0028] When the proportional valve is in the third working state, the second oil passage is communicated with the fourth oil passage through the second groove, and the third oil passage is communicated with the first oil passage through the fourth groove.

[0029] Optionally, in the above-mentioned injection molding machine mold opening and closing hydraulic circuit, when the proportional valve is in the fourth working state, the fourth oil channel, the second groove, the second oil channel, the fifth groove, the third oil channel, the fourth groove, and the first oil channel are connected.

[0030] Optionally, in the above-mentioned injection molding machine mold opening and closing hydraulic circuit, the projections of the first groove, the second groove, the third groove, and the fourth groove on the center plane of the valve core are arranged in sequence along the axial direction of the valve core.

[0031] Optionally, in the above-mentioned injection molding machine mold opening and closing hydraulic circuit, the first groove, the second groove, the third groove, and the fourth groove are respectively provided with one, or a plurality of them are respectively provided along the circumference of the valve core.

[0032] Optionally, in the above-mentioned mold opening and closing hydraulic circuit of the injection molding machine, the fifth groove and the third groove are both located between the second groove and the fourth groove;

[0033] Partial areas of the fifth groove and partial areas of the third groove are alternately arranged in the circumferential direction of the valve core;

[0034] The other area of ​​the fifth groove is closer to the fourth groove than the third groove;

[0035] The other area of ​​the third groove is closer to the second groove than to the fifth groove.

[0036] An injection molding machine system is provided with the injection molding machine mold opening and closing hydraulic circuit described above.

[0037] It can be seen from the above technical solution that the injection molding machine system and its mold opening and closing hydraulic circuit provided by the present invention have the following advantages:

[0038] First, in the mold opening and closing hydraulic circuit of the injection molding machine provided by the present invention, not only can the proportional valve be used to control the working cylinder to realize the mold opening and closing action of the injection molding machine, but also the proportional valve can realize differential mold closing, that is, the proportional valve is a differential proportional valve with a flow regeneration function, and a differential circuit can be formed through the internal structure of the proportional valve. Therefore, compared with the original circuit, the second reversing valve and the intermediate oil circuit can be omitted, thereby reducing the number of valve components, simplifying the oil circuit layout, and helping to save system space.

[0039] Second, since the proportional valve can convert the input electrical signal into force or displacement in proportion, it can continuously control parameters such as pressure and flow, that is, the electrical signal of the proportional valve is easy to adjust, and different flow rates and action characteristics can be achieved. Therefore, in the mold opening and closing hydraulic circuit of the injection molding machine provided by the present invention, the proportional valve can be used to proportionally control the flow of hydraulic oil in and out of the working cylinder 1 according to actual needs during the process of the working cylinder 1 driving the injection molding machine to open and close the mold, thereby infinitely adjusting the mold opening speed and mold closing speed. Therefore, under the premise of realizing all the functions of mold opening and closing, the speed adjustment accuracy, positioning accuracy and repeatability accuracy in the mold opening and closing process can be effectively improved.

[0040] Third, since the proportional valve can proportionally control the flow of hydraulic oil in and out of the working cylinder during the mold closing process of the injection molding machine, the proportional valve can not only quickly open / close the mold, but also achieve a braking effect without setting a brake valve. Therefore, compared with the original circuit, the brake valve can be eliminated, which not only reduces energy consumption, but also eliminates the need for corresponding tests for different models.

[0041] In short, in the mold opening and closing hydraulic circuit of the injection molding machine provided by the present invention, the first reversing valve, the second reversing valve and the brake valve of the original solution are replaced by a differential proportional valve 2 with a flow regeneration function, so that on the premise of realizing all the functions of mold opening and closing, the control accuracy in the mold opening and closing process can be effectively improved, energy consumption can be reduced, the number of system parts can be compressed, the hydraulic circuit can be simplified, the space occupied by the system can be saved, and the system cost can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A schematic diagram of system connection of a mold opening and closing hydraulic circuit of an injection molding machine in the prior art;

[0044] Figure 2 A schematic diagram of system connection of a mold opening and closing hydraulic circuit of an injection molding machine provided by an embodiment of the present invention;

[0045] Figure 3 A schematic diagram of the working state of a proportional valve when a mold opening and closing hydraulic circuit of an injection molding machine controls the mold opening of the injection molding machine provided by an embodiment of the present invention;

[0046] Figures 4 to 6A schematic diagram of three different working states of a proportional valve when a mold opening and closing hydraulic circuit of an injection molding machine controls a mold closing of the injection molding machine provided by an embodiment of the present invention;

[0047] Figure 7 An axonometric view of a valve core inside a proportional valve provided in an embodiment of the present invention;

[0048] Figure 8 A front view of a valve core inside a proportional valve provided by an embodiment of the present invention;

[0049] Fig. 9 for Figure 8 Top view of the spool inside the proportional valve.

[0050] in:

[0051] 01-Mold clamping cylinder, 02-Second reversing valve, 03-First reversing valve, 04-Brake valve,

[0052] 021-intermediate oil circuit, 041-cartridge valve, 042-third reversing valve,

[0053] 1-working cylinder, 2-proportional valve,

[0054] 211-first groove, 212-second groove, 213-third groove, 214-fourth groove,

[0055] 215-Fifth groove,

[0056] 221-first oil passage, 222-second oil passage, 223-third oil passage, 224-fourth oil passage,

[0057] 2211-first opening area, 2212-second opening area,

[0058] 05-safety valve, 051-detection unit, 052-main valve unit, 06-safety door,

[0059] A-second working oil port, B-first working oil port, P-oil inlet, T-oil return port,

[0060] L1-first connecting oil circuit, L2-second connecting oil circuit, L3-oil inlet circuit, L4-oil return circuit. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] See also Figure 2 An embodiment of the present invention provides a hydraulic circuit for opening and closing molds of an injection molding machine. The hydraulic circuit includes a working cylinder 1 and a proportional valve 2. By adjusting the proportional valve 2 to different working states, the working cylinder 1 can be controlled to perform different actions to control the mold opening, mold closing, and differential mold closing of the injection molding machine.

[0063] Specifically, the proportional valve 2 is provided with an oil inlet P, an oil return port T, a first working oil port B and a second working oil port A. The oil inlet P is connected to the oil inlet oil circuit L3, the oil return port T is connected to the oil return oil circuit L4, the first working oil port B is connected to the first cavity 11 of the working cylinder 1 through the first connecting oil circuit L1, and the second working oil port A is connected to the second cavity 12 of the working cylinder 1 through the second connecting oil circuit L2.

[0064] When the proportional valve 2 is in the first working state, that is, Figure 2 The proportional valve 2 in the figure is in the first working position on the far left (see Figure 2 When W1 in the figure is on, the first connecting oil circuit L1 is connected with the oil inlet circuit L3 through the proportional valve 2, and the second connecting oil circuit L2 is connected with the oil return circuit L4 through the proportional valve 2, and the working cylinder 1 controls the injection molding machine to open the mold.

[0065] When the proportional valve 2 is in the second working state, that is, Figure 2 The proportional valve 2 in the figure is in the first working position on the far right (see Figure 2 When W4 is set, the first connecting oil circuit L1 and the second connecting oil circuit L2 are connected through the proportional valve 2, and the working cylinder 1 controls the differential mold clamping of the injection molding machine.

[0066] When the proportional valve 2 is in the third working state, that is, Figure 2 The proportional valve 2 in the figure is in the third working position from the left (see Figure 2 When W3 in the figure, the first connecting oil circuit L1 is connected with the return oil circuit L4 through the proportional valve 2, and the second connecting oil circuit L2 is connected with the oil inlet oil circuit L3 through the proportional valve 2, and the working cylinder 1 controls the mold closing and compaction of the injection molding machine.

[0067] Specifically, the proportional valve 2 also has an H-type middle position function, at which time the first working oil port B, the second working oil port A, the oil inlet port P, and the oil return port T are interconnected, and the system is unloaded. During the mold closing process, if the proportional valve 2 is in the H-type middle position function, the working oil cylinder 1 and the upper mold of the injection molding machine connected thereto are closed under the action of gravity. In specific implementation, the H-type middle position function can be a transition position between other adjacent working positions, such as Figure 2 The H-type neutral position function can also be set as a working position of proportional valve 2 as needed.

[0068] It can be seen that the mold opening and closing hydraulic circuit of the injection molding machine provided by the present invention has the following advantages:

[0069] First, in the mold opening and closing hydraulic circuit of the injection molding machine provided by the present invention, not only can the proportional valve 2 control the working cylinder 1 to realize the mold opening and closing action of the injection molding machine, but also the proportional valve 2 can realize differential mold closing, that is, the proportional valve 2 is a differential proportional valve with a flow regeneration function, and the differential circuit can be formed by the internal structure of the proportional valve 2, so relatively Figure 1 For the original circuit in the system, the second reversing valve 02 and the intermediate oil circuit 021 can be omitted, thereby reducing the number of valve components, simplifying the oil circuit layout, and helping to save system space.

[0070] Second, since the proportional valve can convert the input electrical signal into force or displacement in proportion, it can continuously control parameters such as pressure and flow, that is, the electrical signal of the proportional valve is easy to adjust, and different flow rates and action characteristics can be achieved. Therefore, in the hydraulic circuit of the injection molding machine provided by the present invention, the proportional valve 2 can be used to proportionally control the flow of hydraulic oil in and out of the working cylinder 1 according to actual needs during the process of the working cylinder 1 driving the injection molding machine to open / close the mold, so as to infinitely adjust the mold opening speed / closing speed. Therefore, under the premise of realizing all the functions of mold opening and closing, the speed adjustment accuracy, positioning accuracy and repeatability accuracy in the process of mold opening and closing can be effectively improved.

[0071] Third, since the proportional valve 2 can proportionally control the flow of hydraulic oil in and out of the working cylinder 1 during the mold closing process of the injection molding machine, not only can the proportional valve 2 be used to quickly open / close the mold, but also the proportional valve 2 can achieve a braking effect, without the need to set the brake valve 04, so relatively Figure 1 For the original circuit in the system, the brake valve 04 can be eliminated, which not only reduces energy consumption but also eliminates the need for corresponding tests for different models.

[0072] In short, in the mold opening and closing hydraulic circuit of the injection molding machine provided by the present invention, the first reversing valve 03, the second reversing valve 02 and the brake valve 04 of the original solution are replaced by a differential proportional valve 2 with a flow regeneration function. Therefore, on the premise of realizing all the functions of mold opening and closing, it is possible to effectively improve the control accuracy in the mold opening and closing process, reduce energy consumption, reduce the number of system parts, simplify the hydraulic circuit, save system space, and help reduce system costs.

[0073] In a specific embodiment, the proportional valve 2 includes a valve body, a valve core and a drive device. The valve body is provided with a first working oil port B, a second working oil port A, an oil inlet port P, and an oil return port T; the valve core is relatively movably arranged in the valve body, and is used to control the connection and isolation between different oil ports, that is, to control the proportional valve 2 to switch between different working states; the drive device is used to control the movement of the valve core, so as to adjust the valve core to a suitable working state according to actual conditions.

[0074] Specifically, see Figures 3 to 6The valve body of the proportional valve 2 provided in the embodiment of the present invention is provided with a first oil passage 221, a second oil passage 222, a third oil passage 223, and a fourth oil passage 224. Among them: the first oil passage 221 is connected to the return oil port T, and thus connected to the return oil circuit L4; the second oil passage 222 is connected to the oil inlet port P, and thus connected to the oil inlet circuit L3; the third oil passage 223 is connected to the first working oil port B, and thus connected to the first connecting oil circuit L1; the fourth oil passage 224 is connected to the second working oil port A, and thus connected to the second connecting oil circuit L2. It should be noted here that for ease of understanding, Figures 3 to 6 The first working oil port B, the second working oil port A, the oil inlet port P, and the oil return port T connected to each oil channel are marked respectively.

[0075] In a preferred embodiment, a first groove 211 , a second groove 212 , a third groove 213 , a fourth groove 214 , and a fifth groove 215 are provided on the side wall of the valve core.

[0076] When the proportional valve 2 is in the first working state (see Figure 2 W1 in, such as Figure 3 As shown, the second oil passage 222 and the third oil passage 223 are connected through the third groove 213, so that the oil inlet P is connected to the first working oil port B; and the fourth oil passage 224 is connected to the first opening area 2211 of the first oil passage 221 through the first groove 211, so that the second working oil port A is connected to the oil return port T. At this time, the first connecting oil circuit L1 is connected to the oil inlet circuit L3 through the proportional valve 2, and the second connecting oil circuit L2 is connected to the oil return circuit L4 through the proportional valve 2, and the working oil cylinder 1 controls the mold opening of the injection molding machine.

[0077] When the proportional valve 2 is in the second working state (see Figure 2 W4 in, such as Figure 6 As shown, the second oil passage 222 and the fourth oil passage 224 are connected through the second groove 212, and the second oil passage 222 and the third oil passage 223 are connected through the fifth groove 215. At this time, the first working oil port B and the second working oil port A are both connected to the oil inlet P, so that the first connecting oil circuit L1 and the second connecting oil circuit L2 are connected through the proportional valve 2, and are both connected to the oil inlet P. The working oil cylinder 1 controls the differential mold clamping of the injection molding machine, that is, the oil delivered through the oil inlet P and the oil output from the first cavity 11 of the working oil cylinder through the first connecting oil circuit L1 both enter the second cavity 12 of the working oil cylinder, so as to achieve rapid mold clamping with low energy consumption.

[0078] When the proportional valve 2 is in the third working state (see Figure 2 When W3) in Figure 4As shown, the second oil passage 222 and the fourth oil passage 224 are connected through the second groove 212, so that the oil inlet P is connected to the second working oil port A; the third oil passage 223 and the second opening area 2212 of the first oil passage 221 are connected through the fourth groove 214, so that the first working oil port B is connected to the oil return port T. At this time, the first connecting oil circuit L1 is connected to the oil return circuit L4 through the proportional valve 2, and the second connecting oil circuit L2 is connected to the oil inlet circuit L3 through the proportional valve 2, and the working oil cylinder 1 controls the mold clamping and compaction of the injection molding machine.

[0079] When the proportional valve 2 is in the fourth working state, Figure 5 As shown, the fourth oil channel 224, the second groove 212, the second oil channel 222, the fifth groove 215, the third oil channel 223, the fourth groove 214, and the second opening area 2212 of the first oil channel 221 are connected, that is, the proportional valve 2 is in the H-type middle position function. At this time, the system is unloaded, and the working cylinder 1 and the upper mold of the injection molding machine connected thereto are closed under the action of gravity.

[0080] Specifically, see Figures 7 to 9 The projections of the first groove 211, the second groove 212, the third groove 213, and the fourth groove 214 on the center plane of the valve core are arranged in sequence along the axial direction of the valve core. Moreover, the first groove 211, the second groove 212, the third groove 213, and the fourth groove 214 can be respectively provided with a plurality (for example, two or four) of them along the circumference of the valve core. Alternatively, in other specific embodiments, the first groove 211, the second groove 212, the third groove 213, and the fourth groove 214 can be respectively provided with one.

[0081] Specifically, the fifth groove 215 and the third groove 213 are both located between the second groove 212 and the fourth groove 214. Moreover, a part of the fifth groove 215 and a part of the third groove 213 are arranged alternately in the circumferential direction of the valve core. The other area of ​​the fifth groove 215 is closer to the fourth groove 214 than the third groove 213; the other area of ​​the third groove 213 is closer to the second groove 212 than the fifth groove 215. Thus, Figures 3 to 5 As shown in the figure, the valve core moves relative to the valve body to achieve Figure 3 P and B shown in FIG. are connected through the third groove 213. Figure 4 The PB partition shown in Figure 5 and Figure 6 P and B shown in the figure are connected through the fifth groove 215 to meet the different requirements of mold opening, mold closing, H-type center position function and differential mold closing process.

[0082] In summary, an embodiment of the present invention further provides an injection molding machine system, which includes an injection molding machine mold, and the hydraulic circuit mentioned above for controlling the opening and closing of the injection molding machine mold.

[0083] For specific implementation, see Figure 2 The mold opening and closing hydraulic circuit of the injection molding machine includes a proportional valve 2 (or a proportional reversing valve), a working cylinder 1, a pressure oil inlet end (i.e., the oil inlet P), a mold closing safety valve 05 with a detection function, and a connecting pipeline. The detection part 051 of the safety valve 05 is linked to the safety door 06 of the equipment. Only when the safety door 06 is completely closed, the main valve part 052 of the safety valve 05 can be opened, the pressure oil at the oil supply end can reach the proportional valve 2, and the working cylinder 1 can be actuated. At this time, the installation door 06 triggers the detection part 051, and the detection part 051 controls the main valve part 052 to open, so that the second connecting oil circuit L2 is in a connected state, which can control the action of the working cylinder 1.

[0084] When the mold is opened, the first drive device D1 on the left side of the proportional valve 2 is activated, and the oil enters the first cavity 11 of the working cylinder 1 through the proportional valve 2 (see Figure 2 The mold opening cavity is located on the right side of the working cylinder 1), and the cylinder is pushed to realize the mold opening action. The second cavity 12 (see Figure 2 The oil returns to the oil tank after passing through the proportional valve 2. The whole process is controlled by the proportional valve 2, with high mold opening accuracy and good stability.

[0085] When differential mold closing is required, the second drive device D2 on the right side of proportional valve 2 is activated, and proportional valve 2 enters the right end working position (see Figure 2 W4 in the figure), the pressure oil from the first cavity enters the second cavity through the internal flow channel of the proportional valve 2, realizing a differential circuit and achieving rapid mold closing.

[0086] When mold closing and pressing is required, by adjusting the electrical signal of the given proportional valve 2, the proportional valve 2 enters the third working position from the left (see Figure 2 W3 in the figure can achieve a rapid increase in die pressing force.

[0087] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed.

[0088] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0089] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydraulic circuit for opening and closing molds of an injection molding machine, characterized in that: The invention comprises a working oil cylinder (1) and a proportional valve (2). By adjusting the proportional valve (2) to different working states, the working oil cylinder (1) can be controlled to perform different actions, so as to control the mold opening, mold closing and differential mold closing of the injection molding machine.

2. The mold opening and closing hydraulic circuit of the injection molding machine according to claim 1, characterized in that: The first working oil port (B) and the second working oil port (A) of the proportional valve (2) are connected to the first cavity and the second cavity of the working oil cylinder (1) through the first connecting oil circuit (L1) and the second connecting oil circuit (L2) respectively; the oil inlet (P) and the oil return port (T) of the proportional valve (2) are connected to the oil inlet circuit (L3) and the oil return circuit (L4) respectively; When the proportional valve (2) is in a first working state, the first connecting oil circuit (L1) is connected to the oil inlet circuit (L3) through the proportional valve (2), the second connecting oil circuit (L2) is connected to the oil return circuit (L4) through the proportional valve (2), and the working oil cylinder (1) controls the mold opening of the injection molding machine; When the proportional valve (2) is in the second working state, the first connecting oil circuit (L1) and the second connecting oil circuit (L2) are connected through the proportional valve (2), and the working oil cylinder (1) controls the differential mold clamping of the injection molding machine; When the proportional valve (2) is in the third working state, the first connecting oil circuit (L1) is connected to the oil return circuit (L4) through the proportional valve (2), the second connecting oil circuit (L2) is connected to the oil inlet circuit (L3) through the proportional valve (2), and the working oil cylinder (1) controls the mold closing and compacting of the injection molding machine.

3. The mold opening and closing hydraulic circuit of the injection molding machine according to claim 2, characterized in that: When the proportional valve (2) is in a fourth working state, the first working oil port (B), the second working oil port (A), the oil inlet port (P), and the oil return port (T) are interconnected; The fourth working state is a transition state between the second working state and the third working state; or, the fourth working state is a working position of the proportional valve (2).

4. The mold opening and closing hydraulic circuit of the injection molding machine according to claim 2, characterized in that: The proportional valve (2) comprises a valve body, a valve core and a driving device; The valve body is provided with the first working oil port (B), the second working oil port (A), the oil inlet port (P), and the oil return port (T); The valve core is relatively movably arranged in the valve body, and is used to control the connection and isolation between different oil ports; The driving device is used to control the movement of the valve core.

5. The mold opening and closing hydraulic circuit of the injection molding machine according to claim 4, characterized in that: The valve body is provided with: A first oil passage (221) is communicated with the oil return port (T) to connect to the oil return line (L4); A second oil passage (222) communicates with the oil inlet (P) to connect to the oil inlet circuit (L3); a third oil passage (223) communicating with the first working oil port (B) so as to be connected to the first connecting oil circuit (L1); The fourth oil passage (224) is communicated with the second working oil port (A) to be connected to the second connecting oil circuit (L2).

6. The mold opening and closing hydraulic circuit of the injection molding machine according to claim 5, characterized in that: The side wall of the valve core is provided with a first groove (211), a second groove (212), a third groove (213), a fourth groove (214), and a fifth groove (215); When the proportional valve (2) is in the first working state, the second oil passage (222) and the third oil passage (223) are in communication via the third groove (213), and the fourth oil passage (224) and the first oil passage (221) are in communication via the first groove (211); When the proportional valve (2) is in the second working state, the second oil passage (222) and the fourth oil passage (224) are in communication through the second groove (212), and the second oil passage (222) and the third oil passage (223) are in communication through the fifth groove (215); When the proportional valve (2) is in the third working state, the second oil passage (222) and the fourth oil passage (224) are connected via the second groove (212), and the third oil passage (223) and the first oil passage (221) are connected via the fourth groove (214).

7. The mold opening and closing hydraulic circuit of the injection molding machine according to claim 6, characterized in that: When the proportional valve (2) is in the fourth working state, the fourth oil passage (224), the second groove (212), the second oil passage (222), the fifth groove (215), the third oil passage (223), the fourth groove (214), and the first oil passage (221) are connected.

8. The mold opening and closing hydraulic circuit of the injection molding machine according to claim 6, characterized in that: Projections of the first groove (211), the second groove (212), the third groove (213), and the fourth groove (214) on the center plane of the valve core are arranged in sequence along the axial direction of the valve core; And / or, the first groove (211), the second groove (212), the third groove (213), and the fourth groove (214) are each provided with one, or a plurality of them are respectively provided along the circumference of the valve core.

9. The mold opening and closing hydraulic circuit of the injection molding machine according to claim 7, characterized in that: The fifth groove (215) and the third groove (213) are both located between the second groove (212) and the fourth groove (214); Partial areas of the fifth groove (215) and partial areas of the third groove (213) are alternately arranged in the circumferential direction of the valve core; The other area of ​​the fifth groove (215) is closer to the fourth groove (214) than the third groove (213); The other regions of the third groove (213) are closer to the second groove (212) than to the fifth groove (215).

10. An injection molding machine system, characterized in that: A mold opening and closing hydraulic circuit for an injection molding machine as claimed in any one of claims 1 to 9 is provided.

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