Extrusion injection hydraulic system and control method thereof

Abstract

The invention discloses an extrusion and injection hydraulic system and a control method thereof. The system comprises an injection oil cylinder, a swing oil cylinder, an energy storage loop, an injection loop and a swing loop. The injection oil cylinder and the swing oil cylinder are both rotationally installed on the rack, and the driving end of the swing oil cylinder is hinged to the injection oil cylinder. The swing loop is connected with the swing oil cylinder, so that the swing oil cylinder is driven by the swing loop to drive the injection oil cylinder to swing at a set angle; the energy storage loop and the injection loop are connected to a rodless cavity of the injection oil cylinder in parallel, and the injection loop is further connected with a rod cavity of the injection oil cylinder. The control method is applied to the system. Compared with a traditional mode, the pressure injection device has the beneficial effects that the pressure injection process is carried out through the power source and the energy storage loop together, the pressure injection stability can be effectively improved, and therefore the die casting quality of products is improved. A closed-loop V-P switching point position control method is adopted in the injection process, and the safety and stability of operation in the injection stage can be guaranteed.

Description

Technical Field

[0001] This application relates to the technical field of metal die casting, and particularly relates to an extrusion injection hydraulic system and its control method. Background Art

[0002] Extrusion casting (liquid die forging) technology is currently widely used in industries such as national defense and military, transportation, 3D forming, and communication mobile phones, and has become one of the important technologies in advanced manufacturing technology to achieve near-net-shape forming of complex parts with little or no cutting. The working principle is to directly inject a certain amount of molten metal liquid into the metal die cavity, then close the die to realize the filling and flowing of the metal liquid, and under the action of mechanical static pressure, high-pressure solidification and a small amount of plastic deformation occur, so as to obtain a blank or a part.

[0003] Vertical extrusion injection mainly includes processes such as energy storage, swing vertical, injection, return hammer, and swing tilt. The hydraulic system of traditional extrusion injection is relatively poor in controlling the safety and smoothness of the above injection processes, and it is difficult to meet the high-quality requirements of castings. Summary of the Invention

[0004] One object of this application is to provide an extrusion injection hydraulic system that can solve at least one defect in the above background art.

[0005] Another object of this application is to provide a control method for an extrusion injection hydraulic system that can solve at least one defect in the above background art.

[0006] To achieve at least one of the above objects, the technical solution adopted in this application is: an extrusion injection hydraulic system, including an injection cylinder, a swing cylinder, an energy storage circuit, an injection circuit, and a swing circuit; the injection cylinder and the swing cylinder are both rotatably installed on a frame, and the driving end of the swing cylinder is hinged to the injection cylinder; the swing circuit is connected to the swing cylinder, so that the swing cylinder drives the injection cylinder to swing by a set angle under the drive of the swing circuit; the energy storage circuit and the injection circuit are connected in parallel to the rodless cavity of the injection cylinder, so that during injection, the energy storage circuit and the power source jointly supply oil to the rodless cavity of the injection cylinder through the injection circuit; the injection circuit is also connected to the rod chamber of the injection cylinder, so that during injection, the rod chamber and the rodless cavity of the injection cylinder form a differential connection or are directly connected to the fuel tank.

[0007] Preferably, the energy storage circuit includes an accumulator V411, a cartridge valve V412, and a pilot-operated directional valve V413; the power source is connected to the accumulator V411 through the cartridge valve V412; the control end of the cartridge valve V412 is connected to the accumulator V411 and the fuel tank through the pilot-operated directional valve V413; when energy storage before injection is performed, the pilot-operated directional valve V413 controls the cartridge valve V412 to open, so that the power source supplies oil to the accumulator V411; when injection is performed, the accumulator V411 supplies oil to the injection circuit through the branch of the oil inlet end of the cartridge valve V412.

[0008] Preferably, the injection circuit includes a servo valve V441 and a cartridge valve V442; the oil inlet of the servo valve V441 is connected to the branch of the oil inlet end of the cartridge valve V412, and the oil outlet of the servo valve V441 is connected to the rodless cavity of the injection cylinder; the rodless cavity and the rod cavity of the injection cylinder are connected through the cartridge valve V442; when injection is performed, the servo valve V441 conducts control based on the opening signal of the cartridge valve V412, and then the oil discharged from the accumulator V411 and the oil discharged from the power source both flow through the servo valve V441 to the rodless cavity of the injection cylinder; at the same time, the oil in the rod cavity of the injection cylinder flows back to the rodless cavity through the cartridge valve V442 to form a differential circuit; wherein, the opening degree of the servo valve V441 controls the injection speed.

[0009] Preferably, the injection circuit further includes a cartridge valve V444 and a pilot-operated directional valve V447; the cartridge valve V444 is connected between the rod cavity of the injection cylinder and the fuel tank, and the control end of the cartridge valve V444 is connected to the fuel tank and the power source through the pilot-operated directional valve V447; when the injection cylinder performs boosting injection, the pilot-operated directional valve V447 controls the control end of the cartridge valve V444 to communicate with the fuel tank, so that the oil in the rod cavity of the injection cylinder flows back to the fuel tank through the cartridge valve V444; at this time, the accumulator V411 and the power source keep supplying oil to the rodless cavity of the injection cylinder.

[0010] Preferably, the swing circuit includes a directional valve V421, a check valve V422, and a balance valve V423; the power source is connected to the oil inlet of the directional valve V421 through the check valve V422, the oil return port of the directional valve V421 is connected to the fuel tank, one of the working oil ports of the directional valve V421 is connected to the rod cavity of the swing cylinder, and the other working oil port is connected to the rodless cavity of the swing cylinder through the balance valve V423.

[0011] Preferably, the injection and squeezing hydraulic system further includes a hammer return circuit for driving the injection cylinder to return the hammer; the hammer return circuit includes a pressure relief valve V451, a pilot-operated directional valve V452, a cartridge valve V454, a pilot-operated directional valve V455, and a cartridge valve V456; the pressure relief valve V451 and the cartridge valve V454 are connected in parallel between the rodless chamber of the injection cylinder and the oil tank, and the control end of the cartridge valve V454 is connected between the rodless chamber of the injection cylinder and the oil tank through the pilot-operated directional valve V452; the cartridge valve V456 is connected between the rod chamber of the injection cylinder and the power source, and the control end of the cartridge valve V456 is connected between the power source and the oil tank through the pilot-operated directional valve V455; when the injection is completed, the pressure relief valve V451 is adapted to open first for pressure relief; subsequently, the pilot-operated directional valve V455 controls the opening of the cartridge valve V456 so that the power source supplies oil to the rod chamber of the injection cylinder through the cartridge valve V456; meanwhile, the pilot-operated directional valve V452 controls the opening of the cartridge valve V454 so that the oil in the rodless chamber of the injection cylinder flows back to the oil tank.

[0012] Preferably, a shot sleeve is sealingly and slidably installed at the injection end of the injection cylinder; the shot sleeve is connected to the injection cylinder through a lifting cylinder, and the lifting cylinder is adapted to drive the shot sleeve to expand and contract relative to the injection cylinder under the control of a lifting circuit, so that the injection port of the shot sleeve is sealingly connected to or disengaged from the mold cavity to be die-cast.

[0013] Preferably, the lifting circuit includes a directional valve V431, a balance valve V432, and a pressure valve V433; the inlet port of the directional valve V431 is connected to the power source, and the outlet port of the directional valve V431 is connected to the oil tank; the working oil port of the directional valve V431 is connected to the lifting cylinder through the balance valve V432; the pressure valve V433 is connected between the lifting cylinder and the oil tank; the oil supplied by the power source is adapted to enter the lifting cylinder through the directional valve V431 and the balance valve V432 to drive the shot sleeve to extend relative to the injection cylinder; the oil in the lifting cylinder is adapted to flow back to the oil tank along the balance valve V432 and the directional valve V431 under the action of the gravity of the shot sleeve, so that the shot sleeve retracts relative to the injection cylinder; the pressure valve V433 is used to control the sealing pressure between the shot sleeve and the mold cavity.

[0014] A shot control method, applied to the above-mentioned shot circuit, includes the following steps: converting the expected value of the piston speed of the shot cylinder into the input signal value of servo valve V441; converting the actual input signal value of servo valve V441 into the actual displacement value of the valve core; converting the actual displacement value of the valve core into the actual piston speed value of the shot cylinder and performing feedback; comparing the actual value of the piston speed of the shot cylinder with the expected value, and adjusting the actual input signal value of servo valve V441 through a PID controller according to the comparison result.

[0015] Preferably, determine the shot speed values corresponding to multiple key points according to the shot process requirements; based on the obtained shot speed values corresponding to different key points, generate the expected trajectory of the piston movement speed of the shot cylinder through a curve generation algorithm.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: (1) Compared with the traditional method, in this application, the shot process is carried out jointly by the power source and the energy storage circuit, which can effectively improve the smoothness of the shot, thereby improving the die-casting quality of the product.

[0017] (2) Adopting the closed-loop V-P switching point position control method can ensure the safety and smoothness of the operation in the shot stage, thereby improving production efficiency and enhancing the quality of the castings. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the overall structure of the hydraulic system of this application.

[0019] Figure 2 It is a schematic diagram of the structure of the energy storage circuit in this application.

[0020] Figure 3 It is a schematic diagram of the structure of the swing circuit in this application.

[0021] Figure 4 It is a schematic diagram of the structure of the shot circuit in this application.

[0022] Figure 5 It is a schematic diagram of the structure of the hammer return circuit in this application.

[0023] Figure 6 It is a schematic diagram of the structure of the lifting circuit in this application.

[0024] Figure 7 It is a schematic diagram of the control feedback process of the shot cylinder in this application.

[0025] In the figure: shot cylinder 100, shot sleeve 110, lifting cylinder 200, swing cylinder 300, energy storage circuit 41, swing circuit 42, lifting circuit 43, shot circuit 44, hammer return circuit 45. Detailed Embodiments

[0026] Next, in combination with specific embodiments, the present application will be further described. It should be noted that in the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0027] In the description of the present application, it should be noted that for orientation terms, if there are terms such as "center", "horizontal", "vertical", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation and positional relationship are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of the present application.

[0028] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence.

[0029] In the present application, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In this application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may also include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicating that the horizontal height of the first feature is less than that of the second feature.

[0031] The terms "comprise" and "have" and any variations thereof in the description and claims of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that comprises a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0032] One aspect of this application provides an extrusion injection hydraulic system, as Figure 1 shown, in which a preferred embodiment includes an injection cylinder 100, a swing cylinder 300, an energy storage circuit 41, an injection circuit 44 and a swing circuit 42. The injection cylinder 100 needs to be in a horizontal position to ensure the injection of raw materials. After the injection of the raw materials is completed, the injection oil cylinder 100 needs to rotate to a vertical position for bottom-up extrusion die casting. Therefore, the injection cylinder 100 is rotatably mounted on a frame (not shown). At the same time, the swing cylinder 300 is also rotatably mounted on the frame, and the driving end of the swing cylinder 300 is hinged to the injection cylinder 100. The swing circuit 42 is connected to the swing cylinder 300, so that when the injection cylinder 100 needs to change its position, the swing cylinder 300 can drive the injection cylinder 100 to swing by a set angle under the drive of the swing circuit 42, that is, the injection cylinder 100 swings between the horizontal and vertical directions. The energy storage circuit 41 and the injection circuit 44 are connected in parallel to the rodless chamber A1 of the injection cylinder 100, so that during injection, the energy storage circuit 41 and the power source jointly supply oil to the rodless chamber A1 of the injection cylinder 100 through the injection circuit 44, thereby effectively improving the continuous pressure output during die casting, effectively improving the smoothness of injection, and thus improving the die casting quality of the product. At the same time, the injection circuit 44 is also connected to the rod chamber A2 of the injection cylinder 100, so that during injection, the rod chamber A2 and the rodless chamber A1 of the injection cylinder 100 form a differential connection or are directly connected to the fuel tank; based on the differential connection between the rod chamber A2 and the rodless chamber A1 of the injection cylinder 100, the suppression of sudden changes in injection speed can be achieved, and the stability of the injection process can be further improved.

[0033] It should be noted that the injection cylinder 100, as part of the injection module, has an injection cavity provided therein. The raw material for die casting can be injected into the injection cavity through a ladle. The function of the injection cylinder 100 is to drive a hammer head through a piston to inject the raw material in the injection cavity into the mold cavity by extrusion. The swing cylinder 300 actually drives the injection module and the injection cylinder 100 together; that is, the swing cylinder 300 drives the injection module to be in a horizontal state to inject the raw material in the injection cavity. After the injection of the raw material is completed, the swing cylinder 300 will drive the injection module to be in a vertical state. At this time, the opening of the injection cavity faces upward and is connected to the mold cavity. Then, under the drive of the injection cylinder 100, the raw material in the injection cavity is injected into the mold cavity from bottom to top through the hammer head.

[0034] It can be understood that the drive of the swing cylinder 300 to the injection module can be directly connected to the injection module, or the swing cylinder 300 can be connected to the injection cylinder 100; this embodiment will take the connection between the swing cylinder 300 and the injection cylinder 100 as an example for detailed description. The specific manner of the position drive of the swing cylinder 300 to the injection cylinder 100 is well-known technology to those skilled in the art, so it will not be elaborated in detail here.

[0035] Those skilled in the art should know that the specific working process of the vertical extrusion injection hydraulic system of this application mainly includes an energy storage stage, a swing vertical stage, an injection stage, and a hammer return stage. For the convenience of understanding, the following will specifically describe this stage process.

[0036] In this embodiment, there are various specific structures of the energy storage circuit 41 that can achieve the above functions. For the convenience of understanding, the following will be described in detail through one of the structures. As Figure 2 and Figure 4 shown, the energy storage circuit 41 includes an accumulator V411, a cartridge valve V412, and a pilot-operated directional valve V413. The power source P is connected to the accumulator V411 through the cartridge valve V412; the control end of the cartridge valve V412 is connected to the accumulator V411 and the oil tank T through the pilot-operated directional valve V413. There is also a branch X connecting the cartridge valve V412 and the power source P to the injection circuit 44.

[0037] When the energy storage circuit 41 is not working, the pilot-operated directional valve V413 can deliver part of the oil in the accumulator V411 to the control end of the cartridge valve V412, so that the cartridge valve V412 is in a cut-off state. As a result, the oil output by the power source P cannot enter the accumulator V411, and at the same time, the oil in the accumulator V411 cannot be output either. When energy storage is performed before injection, the pilot-operated directional valve V413 can connect the control end of the cartridge valve V412 to the oil tank T, and then return the oil in the control end to the oil tank T to open the cartridge valve V412; thus, the oil output by the power source P can flow into the accumulator V411 through the cartridge valve V412 for energy storage. When injection is performed, the cartridge valve V412 is in an open state. At this time, the oil in the accumulator V411 can flow through the branch X at the oil inlet end of the cartridge valve V412 to the injection circuit 44; at the same time, the oil output by the power source P can also flow through the branch X to the injection circuit 44. Then, the injection circuit 44 can supply oil to the rodless cavity A1 of the injection cylinder 100 through dual power input to achieve stable injection.

[0038] It should be known that there are various specific structural types of the pilot-operated directional valve V413. For example Figure 2 As shown, in this embodiment, a two-position four-way solenoid directional valve is preferably used. When the energy storage circuit 41 is not working, the coil S401 at the right end of the pilot-operated directional valve V413 is not energized. At this time, the accumulator V411 can be connected to the control end of the cartridge valve V412 through the pilot-operated directional valve V413 to cut off the cartridge valve V412. When the energy storage circuit 41 needs to store energy or assist in injection, the coil S401 at the right end of the pilot-operated directional valve V413 is energized. At this time, the control end of the cartridge valve V412 can be connected to the oil tank T through the pilot-operated directional valve V413, so as to relieve the pressure of the control end to open the cartridge valve V412. It should be noted that the opening of the cartridge valve V412 means that the cartridge valve V412 can be normally opened under the oil pressure at the working oil port.

[0039] In this embodiment, as Figure 2 shown, the energy storage circuit 41 further includes a shuttle valve V414. The shuttle valve V414 is connected between the accumulator V411 and the oil tank T. The shuttle valve V414 is mainly used to prevent pressure backflow and pressure loss caused by oil return when the accumulator V411 releases energy. The specific structure of the shuttle valve V414 is well known to those skilled in the art, so it will not be elaborated in detail here.

[0040] In this embodiment, there are various specific structures of the swing circuit 42 that can achieve the above functions. For the convenience of understanding, one of the structures will be described in detail below. As Figure 3As shown, the swing circuit 42 includes a directional control valve V421, a check valve V422, and a balance valve V423. The power source P is connected to the oil inlet of the directional control valve V421 through the check valve V422. The oil return port of the directional control valve V421 is connected to the oil tank T. One of the working oil ports of the directional control valve V421 is connected to the rod chamber C2 of the swing cylinder 300, and the other working oil port is connected to the rodless chamber C1 of the swing cylinder 300 through the balance valve V423.

[0041] It should be noted that the swing cylinder 300 can drive the injection cylinder 100 to move from horizontal to vertical by extending the piston rod, or it can also drive the injection cylinder 100 to move from horizontal to vertical by contracting the piston rod. In this embodiment, it is preferably that the swing cylinder 300 drives the injection cylinder 100 to move from horizontal to vertical by contracting the piston rod. Then, the specific working process of the swing circuit 42 is as follows: When the injection cylinder 100 needs to swing from horizontal to vertical, the oil fluid output by the power source P passes through the check valve V422 and then flows into the rod chamber C2 of the swing cylinder 300 through the directional control valve V421. At the same time, the oil fluid in the rodless chamber C1 of the swing cylinder 300 can flow back to the oil tank T successively through the balance valve V423 and the directional control valve V421, so as to realize the retraction of the swing cylinder 300. When the injection cylinder 100 needs to swing from vertical to horizontal to realize pouring, the oil fluid output by the power source P passes through the check valve V422 and then through the directional control valve V421 and then through the balance valve V423 and flows into the rodless chamber C1 of the swing cylinder 300. At the same time, the oil fluid in the rod chamber C2 of the swing cylinder 300 can flow back to the oil tank T through the directional control valve V421, so as to realize the extension of the swing cylinder 300.

[0042] It can be understood that the balance valve V423 provides a certain pressure during the swinging process of the injection cylinder 100 to ensure that the swinging of the injection cylinder 100 is more stable. At the same time, it also prevents the injection cylinder 100 from rotating vertically spontaneously due to its own weight in the inclined state, causing impact. The check valve V422 mainly prevents the oil fluid from flowing back when the power source P stops supplying oil, resulting in the swing not reaching the vertical position.

[0043] It should be known that there are various specific structural types of the directional control valve V421. For example Figure 3 As shown, the directional control valve V421 preferably adopts a three-position four-way directional control valve. When the swing circuit 42 is not working, the directional control valve V421 is in the middle cut-off position. When the injection cylinder 100 needs to swing from horizontal to vertical, the right coil S403 of the directional control valve V421 is energized, causing the spool of the directional control valve V421 to move to the left. When the injection cylinder 100 needs to swing from vertical to horizontal to realize pouring, the left coil S402 of the directional control valve V421 is energized, causing the spool of the directional control valve V421 to move to the right.

[0044] In this embodiment, there are various specific structures of the injection circuit 44 that can achieve the above functions. For the convenience of understanding, the following will describe one of the structures in detail. As Figure 4 shown, the injection circuit 44 includes a servo valve V441, a cartridge valve V442, a cartridge valve V444, and a pilot-operated directional valve V447. The inlet port of the servo valve V441 is connected to the branch of the inlet end of the cartridge valve V412, and the outlet port of the servo valve V441 is connected to the rodless chamber A1 of the injection cylinder 100; the rodless chamber A1 and the rod chamber A2 of the injection cylinder 100 are connected by a cartridge valve V442. The cartridge valve V444 is connected between the rod chamber A2 of the injection cylinder 100 and the oil tank, and the control end of the cartridge valve V444 is connected to the oil tank and the power source through the pilot-operated directional valve V447.

[0045] It should be known that the entire injection process can be divided into slow injection, fast injection, and boosting injection; among them, the requirements for injection force in slow injection and fast injection are relatively small, and the same circuit can be used to achieve the injection process. The following will describe in detail the injection processes with different requirements for injection force.

[0046] When the injection cylinder 100 performs slow injection and fast injection, the servo valve V441 can be controlled to conduct based on the opening signal of the cartridge valve V412. Then, the oil discharged from the accumulator V411 and the oil discharged from the power source P can both flow through the servo valve V441 to the rodless chamber A1 of the injection cylinder 100. At the same time, the oil in the rod chamber A2 of the injection cylinder 100 flows back to the rodless chamber A1 through the cartridge valve V442 to form a differential circuit. Among them, the control of the injection speed for slow injection and fast injection can be achieved by controlling the opening of the servo valve V441.

[0047] It can be understood that there are various specific types of the servo valve V441. For example, Figure 4 shown, in this embodiment, a two-position two-way servo valve is preferably used. When the injection circuit 44 is not working, the servo valve V441 is cut off through the cut-off position on the right; when injection work is performed, the coil S406 on the left side of the servo valve V441 is energized, and then the spool of the servo valve V441 moves to the left to achieve the connection of the branch X. It should be known that, in order to ensure the safety of the injection process, an overflow valve V443 can be connected between the rod chamber A2 of the injection cylinder 100 and the oil tank T; when the pressure in the rod chamber A2 is too high, part of the oil can flow back to the oil tank T through the overflow valve V443.

[0048] When the injection cylinder 100 performs boosting injection, the pilot-operated directional valve V447 controls the control end of the cartridge valve V444 to communicate with the oil tank T, so that the oil in the rod chamber A2 of the injection cylinder 100 flows back to the oil tank T through the cartridge valve V444. At this time, the left coil S406 of the servo valve V441 remains energized, so that the accumulator V411 and the power source P keep supplying oil to the rodless chamber A1 of the injection cylinder 100.

[0049] It can be understood that there are various specific types of the pilot-operated directional valve V447. For example Figure 4 As shown, in this embodiment, a K-type three-position four-way directional valve is preferably adopted. The pilot-operated directional valve V447 is also connected to the oil tank T through a pressure valve V445; when the injection cylinder 100 performs slow injection or fast injection, the pilot-operated directional valve V447 is in the middle position. At this time, the control end of the cartridge valve V444 forms a large back pressure through the overflow valve V443 and the pressure valve V445, so as to realize the cut-off of the cartridge valve V444. When the injection cylinder 100 needs to perform boosting injection, the right coil S408 of the pilot-operated directional valve V447 is energized, causing the spool to move leftward. At this time, the pressure valve V445 is opened, and the oil in the control end of the cartridge valve V444 flows back to the oil tank T through the opened pressure valve V445. In order to avoid the oil backflow when the cartridge valve V444 is opened, a check valve V446 can be connected between the control end of the cartridge valve V444 and the pilot-operated directional valve V447.

[0050] In this embodiment, the extrusion injection hydraulic system further includes a hammer return circuit 45 for driving the injection cylinder 100 to perform hammer return; there are various specific structures of the hammer return circuit 4 for realizing the above functions. For the convenience of understanding, one of the structures will be described in detail below. As Figure 5 shown, the hammer return circuit 45 includes a pressure relief valve V451, a pilot-operated directional valve V452, a cartridge valve V454, a pilot-operated directional valve V455, and a cartridge valve V456. The pressure relief valve V451 and the cartridge valve V454 are connected in parallel between the rodless chamber A1 of the injection cylinder 100 and the oil tank T. The control end of the cartridge valve V454 is connected between the rodless chamber A1 of the injection cylinder 100 and the oil tank T through the pilot-operated directional valve V452. The cartridge valve V456 is connected between the rod chamber A2 of the injection cylinder 100 and the power source P. The control end of the cartridge valve V456 is connected between the power source P and the oil tank T through the pilot-operated directional valve V455.

[0051] When the injection is completed, the pressure relief valve V451 can be opened first for pressure relief to avoid the high-pressure oil in the rodless chamber A1 of the injection cylinder 100 causing too fast a hammer return speed and resulting in impact. There are various specific structural types of the pressure relief valve V451; for example Figure 5As shown, the pressure relief valve V451 is a two-position two-way pressure relief valve; when the injection circuit 44 is working normally, the pressure relief valve V451 is in the cut-off position on the left; when a hammer return is required, the coil S409 on the right side of the pressure relief valve V451 is energized, and then the spool moves leftward to connect the rodless cavity A1 with the oil tank T, thereby realizing the pressure relief of the high-pressure oil.

[0052] After the pressure in the rodless cavity A1 of the injection cylinder 100 drops to the set value, the pilot-operated check valve V455 can be controlled to open the cartridge valve V456, so that the power source P supplies oil to the rod cavity A2 of the injection cylinder 100 through the cartridge valve V456; at the same time, the pilot-operated check valve V452 controls the cartridge valve V454 to open, so that the oil in the rodless cavity A1 of the injection cylinder 100 flows back to the oil tank T.

[0053] It can be understood that there are various specific structural types of the pilot-operated check valve V452 and the pilot-operated check valve V455, for example Figure 5 As shown, both the pilot-operated check valve V452 and the pilot-operated check valve V455 are two-position four-way directional control valves. When the injection circuit 44 is working normally, both the pilot-operated check valve V452 and the pilot-operated check valve V455 are in the parallel position. At this time, the rodless cavity A1 of the injection cylinder 100 is connected to the control end of the cartridge valve V454 through the pilot-operated check valve V452, and at the same time, the power source P is connected to the control end of the cartridge valve V456 through the pilot-operated check valve V455. When a hammer return is required, the coil S410 on the right side of the pilot-operated check valve V452 is energized, causing the spool to move leftward. Then, the oil at the control end of the cartridge valve V454 flows through the cross-over circuit to the oil tank T; at the same time, the coil S411 on the left side of the pilot-operated check valve V455 is energized, causing the spool to move rightward. Then, the oil at the control end of the cartridge valve V456 flows through the cross-over circuit to the oil tank T.

[0054] Those skilled in the art should know that in order to ensure the stability of the die-casting process, it is necessary to ensure that when the injection cylinder 100 is injecting, the port of the injection cavity is in a completely sealed state with the mold cavity. Then, when the injection cylinder 100 rotates from the vertical position to the horizontal position again after the die-casting of the product is completed, due to the tight contact between the port of the injection cavity and the mold cavity, it will interfere with the swing of the injection cylinder 100. Therefore, before the injection cylinder 100 swings, it is necessary to first separate the injection cylinder 100 from the mold cavity. There are various specific ways to separate the injection cylinder 100 from the mold cavity, and one of the structures will be described in detail below.

[0055] In this embodiment, as Figure 1As shown in the figure, the injection module includes an injection sleeve 110 for connecting to the mold cavity; the injection sleeve 110 is in sealed sliding connection with the injection end of the injection cylinder 100. The injection sleeve 110 and the injection cylinder 100 are connected by a lifting cylinder 200, and the lifting cylinder 200 can drive the injection sleeve 110 to expand and contract relative to the injection cylinder 100 under the control of the lifting circuit 43, so that the injection port of the injection sleeve 110 is in sealed connection with or disengaged from the mold cavity to be die-cast.

[0056] In this embodiment, there are various specific structures of the lifting circuit 43 that can achieve the above functions. For the convenience of understanding, one of the structures will be described in detail below. As Figure 6 shown, the lifting circuit 43 includes a directional control valve V431, a balance valve V432, and a pressure valve V433. The oil inlet of the directional control valve V431 is connected to the power source P, and the oil return port of the directional control valve V431 is connected to the oil tank T; the working oil port of the directional control valve V431 is connected to the chamber interface B of the lifting cylinder 200 through the balance valve V432; the pressure valve V433 is connected between the lifting cylinder 200 and the oil tank T.

[0057] The oil provided by the power source P can enter the chamber of the lifting cylinder 200 through the directional control valve V431 and the balance valve V432 to drive the injection sleeve 110 to extend relative to the injection cylinder 100. The oil in the lifting cylinder 200 can flow back to the oil tank T along the balance valve V432 and the directional control valve V431 under the action of the gravity of the injection sleeve 110, so that the injection sleeve 110 retracts relative to the injection cylinder 100. The pressure valve V433 is used to control the sealing pressure between the injection sleeve 110 and the mold cavity.

[0058] It can be understood that the specific number of the lifting cylinders 200 can be set to one or multiple. Multiple lifting cylinders 200 are all connected to the balance valve V432 and the pressure valve V433. There are various ways to connect the lifting cylinders 200. For example, the lifting cylinder 200 is connected to the injection sleeve 110 through the cylinder body, and at the same time the piston rod of the lifting cylinder 200 is connected to the injection cylinder 100; of course, it can also be installed in the reverse way, and the specific installation can be selected according to the actual needs of those skilled in the art.

[0059] It should be known that there are various specific structural types of the directional control valve V431, such as Figure 6As shown in the figure, the reversing valve V431 adopts an O-type three-position four-way reversing valve. When the lifting cylinder 200 is not working, the reversing valve V431 is in the middle cut-off position. When the lifting cylinder 200 lifts the injection sleeve 110, the coil S404 on the left side of the reversing valve V431 is energized, and then the spool moves to the right, so that the reversing valve V431 connects the power source P to the balance valve V432 through the crossover position. When the lifting cylinder 200 retracts the injection sleeve 110, the coil S405 on the right side of the reversing valve V431 is energized, and then the spool moves to the left, so that the reversing valve V431 connects the fuel tank T to the balance valve V432 through the parallel position.

[0060] Another aspect of the present application provides an injection control method, which is applied to the injection circuit 44 described above, as Figure 7 shown. One preferred embodiment includes the following steps: converting the expected value of the piston speed of the injection cylinder 100 into the input signal value of the servo valve V441. Converting the actual input signal value of the servo valve V441 into the actual displacement value of the spool. Converting the actual displacement value of the spool into the actual piston speed value of the injection cylinder 100 and performing feedback. Comparing the actual value of the piston speed of the injection cylinder 100 with the expected value, and adjusting the actual input signal value of the servo valve V441 through a PID controller according to the comparison result.

[0061] Specifically, as Figure 7 shown, the expected piston speed of the injection cylinder 100 can be represented by the function R(S), the transfer function of the servo valve V441 is represented by G1(S), the injection cylinder 100 is represented by the transfer function G2(S), the transfer function of the feedback channel is H(S), the transfer function of the feedforward channel is G4(S), and the actual movement speed of the piston of the injection cylinder 100 is represented by the function C(S). Then the specific control process of the injection circuit 44 is as follows: input the change situation R(S) of the expected piston speed value of the injection cylinder 100 into the control system. First, convert the piston speed value into the input signal value of the servo valve V441 through the transfer function G4(S). Then, the servo valve V441 converts the actual input signal value into the actual displacement value of the spool through the function G1(S), and then can control the spool to move accordingly. Then, convert the actual displacement value of the spool into the actual piston speed value of the injection cylinder 100 through the function G2(S). Finally, feedback the actual piston speed value of the injection cylinder 100 through the function H(S), subtract the actual speed value from the expected speed value, and adjust the actual input signal value of the servo valve V441 through a PID controller to finally achieve an accurate control effect. Compared with the traditional method, this embodiment adopts a closed-loop V-P switching point position control method, which can ensure the safety and stability of the injection stage operation, thereby improving production efficiency and enhancing the quality of castings.

[0062] It can be understood that by setting the expected trajectory of the piston movement speed of the injection cylinder 100 and converting it into a control signal for the servo valve V441, the servo valve V441 can be controlled, thereby realizing the movement control of the injection cylinder 100. By measuring the movement speed of the injection cylinder 100 as the feedback signal of the control system, the deviation value between this signal and the expected signal is corrected using the PID control algorithm, thereby realizing the precise speed control of the injection cylinder 100. Among them, the feedforward control is mainly used to overcome or reduce the fluctuations in the system speed caused by external disturbances. The control signal output through the feedforward control channel will directly act on the servo valve V441 at the inlet of the injection cylinder 100, thereby improving the fast response speed of the system.

[0063] It should be known that for the setting of the expected trajectory of the piston movement speed of the injection cylinder 100, the injection speed values corresponding to multiple key points can be determined according to the requirements of the injection process; based on the obtained injection speed values corresponding to different key points, the expected trajectory of the piston movement speed of the injection cylinder 100 is generated through a curve generation algorithm.

[0064] The above describes the basic principle, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present application. Without departing from the spirit and scope of the present application, the present application will have various changes and improvements, and these changes and improvements all fall within the scope of the present application claimed. The scope of protection required by the present application is defined by the appended claims and their equivalents.

Claims

1. A squeeze casting hydraulic system, characterized in that, Comprising: A shot cylinder and a swing cylinder; the shot cylinder and the swing cylinder are both rotatably mounted on the frame, and the driving end of the swing cylinder is hinged to the shot cylinder; A swing circuit; the swing circuit is connected to the swing cylinder so that the swing cylinder drives the shot cylinder to swing at a set angle under the drive of the swing circuit; and An energy storage circuit and a shot circuit; the energy storage circuit and the shot circuit are connected in parallel to the rodless cavity of the shot cylinder, so that during shot, the energy storage circuit and the power source jointly supply oil to the rodless cavity of the shot cylinder through the shot circuit; The shot circuit is also connected to the rod chamber of the shot cylinder, so that during shot, the rod chamber and the rodless cavity of the shot cylinder form a differential connection or are directly connected to the fuel tank.

2. The squeeze casting hydraulic system according to claim 1, wherein The energy storage circuit includes an accumulator (V411), a cartridge valve (V412) and a pilot operated directional valve (V413); The power source is connected to the accumulator (V411) through the cartridge valve (V412); the control end of the cartridge valve (V412) is connected to the accumulator (V411) and the fuel tank through the pilot operated directional valve (V413); When energy storage is carried out before shot, the pilot operated directional valve (V413) controls the cartridge valve (V412) to open, so that the power source supplies oil to the accumulator (V411); When shot is carried out, the accumulator (V411) supplies oil to the shot circuit through the branch at the inlet end of the cartridge valve (V412).

3. The squeeze casting hydraulic system according to claim 2, wherein The shot circuit includes a servo valve (V441) and a cartridge valve (V442); The inlet port of the servo valve (V441) is connected to the branch at the inlet end of the cartridge valve (V412), and the outlet port of the servo valve (V441) is connected to the rodless cavity of the shot cylinder; the rodless cavity and the rod chamber of the shot cylinder are connected through the cartridge valve (V442); When shot is carried out, the servo valve (V441) conducts control based on the opening signal of the cartridge valve (V412), and then the oil discharged from the accumulator (V411) and the oil discharged from the power source both flow through the servo valve (V441) to the rodless cavity of the shot cylinder; The oil in the rod chamber of the shot cylinder flows back to the rodless cavity through the cartridge valve (V442) to form a differential circuit; Wherein, the opening degree of the servo valve (V441) controls the shot speed.

4. The extrusion injection hydraulic system according to claim 3, characterized in that, The shot circuit further includes a cartridge valve (V444) and a pilot operated directional valve (V447); The cartridge valve (V444) is connected between the rod chamber of the shot cylinder and the fuel tank, and the control end of the cartridge valve (V444) is connected to the fuel tank and the power source through the pilot operated directional valve (V447); When the shot cylinder performs boosting shot, the pilot operated directional valve (V447) controls the control end of the cartridge valve (V444) to communicate with the fuel tank, and then the oil in the rod chamber of the shot cylinder flows back to the fuel tank through the cartridge valve (V444); At this time, the accumulator (V411) and the power source continue to supply oil to the rodless chamber of the injection cylinder.

5. The squeeze casting hydraulic system according to claim 1, wherein, The swing circuit includes a directional control valve (V421), a check valve (V422), and a balance valve (V423); The power source is connected to the oil inlet of the directional control valve (V421) through the check valve (V422). The oil return port of the directional control valve (V421) is connected to the oil tank. One of the working oil ports of the directional control valve (V421) is connected to the rod chamber of the swing cylinder, and the other working oil port is connected to the rodless chamber of the swing cylinder through the balance valve (V423).

6. The squeeze casting hydraulic system according to claim 1, wherein, The extrusion injection hydraulic system further includes a hammer return circuit for driving the injection cylinder to return the hammer; the hammer return circuit includes a pressure relief valve (V451), a pilot-operated directional control valve (V452), a cartridge valve (V454), a pilot-operated directional control valve (V455), and a cartridge valve (V456); The pressure relief valve (V451) and the cartridge valve (V454) are connected in parallel between the rodless chamber of the injection cylinder and the oil tank; The control end of the cartridge valve (V454) is connected between the rodless chamber of the injection cylinder and the oil tank through the pilot-operated directional control valve (V452); The cartridge valve (V456) is connected between the rod chamber of the injection cylinder and the power source, and the control end of the cartridge valve (V456) is connected between the power source and the oil tank through the pilot-operated directional control valve (V455); When the injection is completed, the pressure relief valve (V451) is adapted to open first for pressure relief; Subsequently, the pilot-operated directional control valve (V455) controls the opening of the cartridge valve (V456) so that the power source supplies oil to the rod chamber of the injection cylinder through the cartridge valve (V456); at the same time, the pilot-operated directional control valve (V452) controls the opening of the cartridge valve (V454) so that the oil in the rodless chamber of the injection cylinder flows back to the oil tank.

7. The squeeze casting hydraulic system according to any one of claims 1-6, characterized in that, A seal sliding installation of the injection end of the injection cylinder is provided with an injection sleeve; The injection sleeve and the injection cylinder are connected through a lifting cylinder. The lifting cylinder is adapted to drive the injection sleeve to expand and contract relative to the injection cylinder under the control of the lifting circuit, so that the injection port of the injection sleeve is hermetically connected to or disengaged from the die cavity to be die-cast.

8. The extrusion injection hydraulic system according to claim 7, characterized in that, The lifting circuit includes a directional control valve (V431), a balance valve (V432), and a pressure valve (V433); The oil inlet of the directional control valve (V431) is connected to the power source, and the oil return port of the directional control valve (V431) is connected to the oil tank; the working oil port of the directional control valve (V431) is connected to the lifting cylinder through the balance valve (V432); the pressure valve (V433) is connected between the lifting cylinder and the oil tank; The oil provided by the power source is adapted to enter the lifting cylinder through the directional control valve (V431) and the balance valve (V432) to drive the injection sleeve to extend relative to the injection cylinder; The oil in the lifting cylinder is adapted to flow back to the oil tank along the balance valve (V432) and the directional control valve (V431) under the action of the gravity of the injection sleeve, so that the injection sleeve retracts relative to the injection cylinder; The pressure valve (V433) is used to control the sealing pressure between the injection sleeve and the mold cavity.

9. A shot control method, applied to the extrusion shot hydraulic system according to claim 1, characterized in that, The steps include: Converting the expected value of the piston speed of the injection cylinder into the input signal value of the servo valve (V441); Converting the actual input signal value of the servo valve (V441) into the actual displacement value of the valve core; Converting the actual displacement value of the valve core into the actual piston speed value of the injection cylinder and performing feedback; Comparing the actual value of the piston speed of the injection cylinder with the expected value, and adjusting the actual input signal value of the servo valve (V441) through a PID controller according to the comparison result.

10. The injection control method according to claim 9, wherein Determining the injection speed values corresponding to multiple key points according to the injection process requirements; based on the obtained injection speed values corresponding to different key points, generating the expected trajectory of the piston movement speed of the injection cylinder through a curve generation algorithm.

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