Hydraulic control system of hydraulic stretcher

Abstract

The utility model discloses a hydraulic control system of a hydraulic stretcher. The hydraulic control system comprises an oil tank, an oil pump, a main oil cylinder hydraulic control system and an edge pressing cylinder hydraulic control system, a first blank pressing cylinder is used for providing blank pressing force for a workpiece when the workpiece is stretched and formed for the first time, and a second blank pressing cylinder is used for providing blank pressing force for the workpiece when the workpiece is stretched and formed for the second time and later time; the second blank pressing cylinder hydraulic control system comprises a hydraulic valve group; and a stop valve is arranged in a hydraulic pipeline for communicating the hydraulic valve group with the rodless cavity of the second blank pressing cylinder. Through independent control over a main oil cylinder, a second blank pressing cylinder and a first blank pressing cylinder, in the hydraulic stretching process, when the first blank pressing cylinder acts, a stop valve in a hydraulic control system of the second blank pressing cylinder is switched off, so that an oil inlet pipeline of a rodless cavity of the second blank pressing cylinder is rapidly cut off, and a hydraulic rod of the second blank pressing cylinder is kept relatively immovable; and in the re-stretching process, the second blank pressing cylinder acts independently, so that multiple times of stretching forming of the workpiece are completed.

Description

Technical Field

[0001] The utility model belongs to the field of hydraulic forming, and in particular relates to a hydraulic control system for a hydraulic stretching machine. Background Art

[0002] In the hydraulic forming industry, hydraulic stretching machines utilize the action of fluid within a hydraulic system. For thin sheet metal products, hydraulic stretching offers advantages such as ease of processing and the ability to easily form special shapes. Therefore, many thin sheet metal products are currently processed using hydraulic stretching. For example, patent application CN106513484A discloses a "filter housing stretching machine." In its initial state, the upper and lower mold assemblies are in an open position. The first and second pressure cylinders operate to align the lower blanking die, the pressure block, and the top surface of the first stretching die (i.e., the surface facing the upper die assembly). The upper die assembly is in the upward stop position, with the guide pins still within the guide pin sleeves. After the sheet metal is fed into the stretching machine along the guide plate, the main cylinder activates, driving the movable crossbar downward rapidly. This in turn drives the upper blanking die toward the lower blanking die until the speed sensor detects the speed sensor. The main cylinder then adjusts the downward speed, causing the movable crossbar to slowly descend. Because the upper blanking die is located closest to the lower die assembly, it contacts the sheet material first, and the upper and lower dies then begin blanking. Once blanking is complete, the sheet material falls into the blanking hole within the lower die. Subsequently, the first blank holder generates pressure, while the second blank holder remains stationary (in a "holding pressure" state), forcing the upper blanking die to press against the pressure block, clamping the sheet material between the upper blanking die and the pressure block. As the main cylinder continues to drive the upper blanking die downward, the sheet material is stretched by the first stretching die. At this point, the first stretching die acts as the punch, while the upper blanking die acts as the die. The sheet material undergoes its first stretch along the longitudinal direction of the first stretching die and enters the interior of the lower blanking die. When the movable crossbar continues to descend until the blank holder force conversion sensor switch senses the blank holder force conversion sensing block, the first stretching operation ends. The pressure valve of the first blank holder cylinder is relieved, while the second blank holder cylinder generates pressure, clamping the sheet metal between the clamping edge and the holding block. As the main cylinder continues to drive the upper blanking die downward, the sheet metal is stretched by the second drawing die. The second drawing die acts as the punch, while the upper drawing die acts as the concave. The sheet metal undergoes a second stretch along the longitudinal direction of the second drawing die and enters the interior of the upper drawing die. The main cylinder continues to descend until the first downward stroke sensor switch senses the first downward stroke sensing block, at which point the main cylinder stops and releases pressure. After the master cylinder's pressure relief time reaches the set value, the main cylinder will then drive the movable crossbar upward, thereby driving the upper die assembly upward until the first upward stroke sensor switch senses the first upward stroke sensing block. At this point, the main cylinder stops, and the movable crossbar returns to its initial position.At the same time, the first and second margin clamping cylinders will operate, respectively driving the pressure block and the first stretching die upward, until the second upward stroke sensing switch senses the second upward stroke sensing block, and the third upward stroke sensing switch senses the third upward stroke sensing block. The first and second margin clamping cylinders will then stop and unload, and the top surfaces of the blanking lower die, the pressure block, and the first stretching die will return to being flush, completing a working cycle. During a working cycle, the second downward stroke sensing switch and the second downward stroke sensing block, as well as the third downward stroke sensing switch and the third downward stroke sensing block, can play a protective role, preventing the first or second margin clamping cylinder from damaging the lower die assembly due to excessive downward travel.

[0003] However, the above-mentioned filter housing stretching machine does not disclose a related hydraulic pipeline control system, so it is necessary to design a hydraulic pipeline control system that can be used to implement the working process of the above-mentioned filter housing stretching machine. Utility Model Content

[0004] In order to overcome the deficiencies in the prior art, the utility model provides a hydraulic control system for a hydraulic stretching machine; the hydraulic control system for the hydraulic stretching machine can not only realize independent control of the main oil cylinder, the second edge pressing cylinder and the first edge pressing cylinder, but also can quickly cut off the oil inlet of the rodless chamber of the second edge pressing cylinder when the first edge pressing cylinder is actuated, so that the hydraulic rod of the second edge pressing cylinder remains relatively motionless.

[0005] The technical solution of the utility model to solve the above technical problems is:

[0006] A hydraulic control system for a hydraulic stretching machine, comprising an oil tank (1), an oil pump (6), a main oil cylinder hydraulic control system for controlling the operation of a main oil cylinder (C), and a pressure cylinder hydraulic control system for controlling the operation of a pressure cylinder, wherein the pressure cylinder is used to provide a pressure force for a workpiece during the stretching and forming of the workpiece, wherein the first pressure cylinder (B) provides the pressure force for the workpiece during the first stretching and forming, and the second pressure cylinder (A) provides the pressure force for the workpiece during the second and subsequent stretching and forming; wherein,

[0007] The hydraulic control system of the edge pressing cylinder is divided into a first hydraulic control system of the edge pressing cylinder and a second hydraulic control system of the edge pressing cylinder;

[0008] The second edge pressing cylinder hydraulic control system includes a hydraulic valve group for controlling the operation of the second edge pressing cylinder (A); and a shut-off valve for opening or closing the hydraulic pipeline is provided in the hydraulic pipeline connecting the hydraulic valve group and the rodless chamber of the second edge pressing cylinder (A).

[0009] Preferably, the hydraulic valve group includes a first electro-hydraulic reversing valve (14), wherein the oil inlet of the oil pump (6) is connected to the oil tank (1), and the oil outlet is connected to the oil inlet of the first electro-hydraulic reversing valve (14); the first oil outlet of the first electro-hydraulic reversing valve (14) is connected to the oil inlet of the stop valve, and the oil outlet of the stop valve is connected to the rodless cavity of the second pressure cylinder (A); the rod cavity of the second pressure cylinder (A) is connected to the second oil outlet of the first electro-hydraulic reversing valve (14); and the oil return port of the first electro-hydraulic reversing valve (14) is connected to the oil tank (1).

[0010] Preferably, the stop valve is a second electro-hydraulic reversing valve (19), the oil inlet of the second electro-hydraulic reversing valve (19) is connected to the first oil outlet of the first electro-hydraulic reversing valve (14), the second oil outlet of the second electro-hydraulic reversing valve (19) is connected to the rodless chamber of the second pressure cylinder (A), and the oil return port is connected to the oil tank (1).

[0011] Preferably, the second edge pressing cylinder (A) is in multiple groups, and the multiple groups of second edge pressing cylinders (A) operate in sequence; each group of second edge pressing cylinders (A) is controlled by an independent second edge pressing cylinder hydraulic control system; when the first edge pressing cylinder (B) operates, the stop valves in the multiple groups of second edge pressing cylinder hydraulic control systems are disconnected; when the second edge pressing cylinder (A) of the previous level operates, the stop valves in all the second edge pressing cylinder hydraulic control systems of the next level and below are disconnected.

[0012] Preferably, the hydraulic control system of the first edge pressing cylinder includes a third electro-hydraulic reversing valve (14a), the oil inlet of the third electro-hydraulic reversing valve (14a) is connected to the oil outlet of the oil pump (6), the first oil outlet is connected to the rodless cavity of the first edge pressing cylinder (B); the second oil outlet is connected to the rod cavity of the first edge pressing cylinder (B), and the return port is connected to the oil tank (1).

[0013] Preferably, the master cylinder hydraulic control system further includes a fast cylinder (D).

[0014] Preferably, the master cylinder hydraulic control system includes a filling valve (26), a fourth electro-hydraulic reversing valve (12) and a fifth electro-hydraulic reversing valve (13), wherein the oil inlet of the fifth electro-hydraulic reversing valve (13) is connected to the oil outlet of the oil pump (6), the second oil outlet is connected to the rodless cavity of the master cylinder (C), and the oil return port is connected to the oil tank (1); the rod cavity of the master cylinder (C) is connected to the second oil outlet of the fourth electro-hydraulic reversing valve (12), and an overflow valve (20a) and a one-way sequence valve (22) are provided on the hydraulic pipeline connecting the two; the oil return port of the fourth electro-hydraulic reversing valve (12) is connected to the oil tank (1), and the first oil outlet of the fourth electro-hydraulic reversing valve (12) is connected to the rodless cavity of the fast cylinder (D); the rodless cavity of the master cylinder (C) is also connected to the filling tank (28), and a filling valve (26) is provided on the hydraulic pipeline connecting the two.

[0015] Preferably, the main oil cylinder hydraulic control system also includes a lifting cylinder (E) and a lifting cylinder hydraulic control system for controlling the operation of the lifting cylinder (E), wherein the lifting cylinder hydraulic control system includes an electromagnetic reversing valve (11), the oil inlet of the electromagnetic reversing valve (11) is connected to the oil outlet of the oil pump (6), and a superimposed pressure reducing valve (27) is provided on the hydraulic pipeline connecting the two; the first oil outlet of the electromagnetic reversing valve (11) is connected to the rod cavity of the lifting cylinder (E), the second oil outlet is connected to the rodless cavity of the lifting cylinder (E), and the oil return port is connected to the oil tank (1).

[0016] Preferably, an oil filter (2) is provided on the hydraulic pipeline between the oil inlet of the oil pump (6) and the oil tank (1).

[0017] Preferably, a one-way valve (8) is provided on the hydraulic pipeline connected to the oil outlet of the oil pump (6).

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] The hydraulic control system of the hydraulic stretching machine of the present invention is specially designed to adapt to the "stretching machine for filter housing" in the existing technology; during the first hydraulic stretching process, when the first pressure cylinder is actuated, the stop valve can quickly cut off the oil inlet pipe of the rodless chamber of the second pressure cylinder, so that the hydraulic oil in the rodless chamber of the second pressure cylinder cannot be discharged, so during the first stretching (that is, when the first pressure cylinder moves downward), the second pressure cylinder can remain relatively motionless; and in the second stretching process, the second pressure cylinder hydraulic control system controls the second pressure cylinder to move independently, thereby completing the secondary or multiple stretching forming of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the hydraulic piping diagram of the hydraulic control system of the hydraulic stretching machine of the present utility model. DETAILED DESCRIPTION

[0021] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0022] See also Figure 1 The hydraulic control system of the hydraulic stretching machine of the utility model is designed for the invention patent application with application publication number CN106513484A which discloses a "stretching machine for filter housing", and is used to realize the secondary stretching process of the stretching machine for filter housing.

[0023] To this end, the hydraulic control system of the hydraulic stretching machine of the present invention includes an oil tank 1, an oil pump 6, a main oil cylinder hydraulic control system for controlling the operation of the main oil cylinder C and a side holding cylinder hydraulic control system for controlling the operation of the side holding cylinder, the side holding cylinder is used to provide a side holding force for the workpiece during the stretching and forming of the workpiece, wherein the first side holding cylinder B provides the side holding force for the workpiece during the first stretching and forming, and the second side holding cylinder A provides the side holding force for the workpiece during the second and subsequent stretching and forming; wherein, the side holding cylinder hydraulic control system is divided into a first side holding cylinder hydraulic control system and a second side holding cylinder hydraulic control system;

[0024] The second edge pressing cylinder hydraulic control system includes a hydraulic valve group for controlling the operation of the second edge pressing cylinder A; and a stop valve for opening or closing the hydraulic pipeline is provided in the hydraulic pipeline connecting the hydraulic valve group and the rodless chamber of the second edge pressing cylinder A.

[0025] Among them, the second edge pressing cylinder A is a plurality of groups, and the plurality of second edge pressing cylinders A act in sequence; each group of second edge pressing cylinders A is controlled by an independent second edge pressing cylinder hydraulic control system; when the first edge pressing cylinder B acts, the stop valves in the plurality of second edge pressing cylinder hydraulic control systems are disconnected; when the second edge pressing cylinder A of the upper level acts, the stop valves in the second edge pressing cylinder hydraulic control system of the lower level and its lower level are disconnected; through the above settings, multiple stretching of the sheet can be achieved; and in this embodiment, the first edge pressing cylinder B and the second edge pressing cylinder A are both a group, so the hydraulic control system of the hydraulic stretching machine of the utility model can achieve secondary stretching of the sheet.

[0026] See also Figure 1 The hydraulic valve group includes a first electro-hydraulic reversing valve 14, the oil inlet of the oil pump 6 is connected to the oil tank 1, and the oil outlet is connected to the oil inlet of the first electro-hydraulic reversing valve 14; the first oil outlet of the first electro-hydraulic reversing valve 14 is connected to the oil inlet of the stop valve, and the oil outlet of the stop valve is connected to the rodless cavity of the second pressure cylinder A; the rod cavity of the second pressure cylinder A is connected to the second oil outlet of the first electro-hydraulic reversing valve 14; the oil return port of the first electro-hydraulic reversing valve 14 is connected to the oil tank 1.

[0027] In this embodiment, the shut-off valve is a second electro-hydraulic reversing valve 19, the oil inlet of the second electro-hydraulic reversing valve 19 is connected to the first oil outlet of the first electro-hydraulic reversing valve 14, the second oil outlet of the second electro-hydraulic reversing valve 19 is connected to the rodless chamber of the second pressure cylinder A, and the oil return port is connected to the oil tank 1.

[0028] The working mode of the second edge holding cylinder A is controlled by controlling the power on and off of the electromagnets in the first electro-hydraulic reversing valve 14 and the second electro-hydraulic reversing valve 19 respectively, specifically:

[0029] 1. When the oil inlet and the second oil outlet of the second electro-hydraulic reversing valve 19 are disconnected, the hydraulic oil in the rodless chamber of the second edge pressing cylinder A cannot flow out, and the hydraulic rod of the second edge pressing cylinder A is relatively stationary;

[0030] 2. When the oil inlet and the second oil outlet of the second electro-hydraulic reversing valve 19 are connected, the oil inlet and the first oil outlet of the first electro-hydraulic reversing valve 14 are connected, and the second oil outlet and the oil return port are connected, the rodless cavity of the second edge clamping cylinder A is connected to the oil outlet of the oil pump 6, and the rod cavity is connected to the oil tank 1, and the hydraulic oil enters the rodless cavity of the second edge clamping cylinder A, pushing the hydraulic rod to extend;

[0031] 3. When the oil inlet and the second oil outlet in the second electro-hydraulic reversing valve 19 are connected, the oil inlet and the second oil outlet in the first electro-hydraulic reversing valve 14 are connected, and the first oil outlet and the oil return port are connected, the rodless chamber of the second edge pressing cylinder A is connected to the oil tank 1, and the rod chamber is connected to the oil inlet of the oil pump 6; the hydraulic oil enters the rod chamber of the second edge pressing cylinder A, pushing the hydraulic rod to retract.

[0032] See also Figure 1 An overflow valve 20 is provided on the hydraulic pipeline between the rod chamber of the second edge pressing cylinder A and the second oil outlet of the first electro-hydraulic reversing valve 14; the oil inlet of the overflow valve 20 is connected to the hydraulic pipeline, and the oil outlet is connected to the oil tank 1.

[0033] See also Figure 1 A first hydraulic branch connected to the oil tank 1 is provided on the hydraulic pipeline between the oil inlet of the second electro-hydraulic reversing valve 19 and the first oil outlet of the first electro-hydraulic reversing valve 14, and an overflow valve 17 is provided on the first hydraulic branch.

[0034] See also Figure 1 , the second pressure cylinder hydraulic control system also includes a remote pressure regulating valve 15 and an electromagnetic reversing valve 16, wherein the oil inlet of the electromagnetic reversing valve 16 is connected to the oil inlet of the relief valve 17, the first oil outlet is connected to the oil inlet of the remote pressure regulating valve 15, and the oil outlet of the remote pressure regulating valve 15 is connected to the oil tank 1;

[0035] When the oil inlet of the solenoid reversing valve 16 is connected to the first oil outlet, the second oil outlet is blocked, and the oil return port is connected to the oil tank, the remote pressure regulating valve 15 and the relief valve 17 are both in working state, and the pressure setting value of the remote pressure regulating valve 15 is lower than the pressure setting value of the relief valve 17;

[0036] When the first oil outlet and the oil return port in the electromagnetic reversing valve 16 are connected, and the oil inlet and the second oil outlet are connected, the second oil outlet is blocked, the oil return port is connected to the oil tank 1, and the remote pressure regulating valve 15 is disconnected from the first hydraulic branch. At this time, the remote pressure regulating valve 15 does not play a remote control role, and the relief valve 17 plays a pressure regulation role.

[0037] See also Figure 1 , the first edge pressing cylinder hydraulic control system includes a third electro-hydraulic reversing valve 14a, the oil inlet of the third electro-hydraulic reversing valve 14a is connected to the oil outlet of the oil pump 6, the first oil outlet is connected to the rodless cavity of the first edge pressing cylinder B; the second oil outlet is connected to the rod cavity of the first edge pressing cylinder B, and the oil return port is connected to the oil tank 1;

[0038] By controlling the power on and off of the electromagnet in the third electro-hydraulic reversing valve 14a, the following control is achieved:

[0039] 1. When the oil inlet and the first oil outlet of the third electro-hydraulic reversing valve 14a are connected, and the second oil outlet and the oil return port are connected, the rodless cavity of the first edge pressing cylinder B is connected to the oil outlet of the oil pump 6, and the rod cavity of the first edge pressing cylinder B is connected to the oil tank 1. Therefore, hydraulic oil enters the rodless cavity of the first edge pressing cylinder B, pushing the hydraulic rod to extend;

[0040] 2. When the oil inlet and the second oil outlet in the third electro-hydraulic reversing valve 14a are connected, and the first oil outlet and the oil return port are connected, the rod chamber of the first side pressing cylinder B is connected to the oil inlet of the oil pump 6, and the rodless chamber of the first side pressing cylinder B is connected to the oil tank 1. Therefore, the hydraulic oil enters the rod chamber of the first side pressing cylinder B, pushing the hydraulic rod to retract.

[0041] See also Figure 1 A second hydraulic branch connected to the oil tank 1 is provided on the hydraulic pipeline between the return oil port of the first edge pressing cylinder B and the second oil outlet of the third electro-hydraulic reversing valve 14a, and an overflow valve 24 is provided on the second hydraulic branch; a third hydraulic branch for connecting to the oil tank 1 is provided between the rodless chamber of the first edge pressing cylinder B and the first oil outlet of the third electro-hydraulic reversing valve 14a, and an overflow valve 17a is provided on the third hydraulic branch.

[0042] See also Figure 1, the first pressure cylinder hydraulic control system also includes a remote pressure regulating valve 15a and an electromagnetic reversing valve 23, wherein the first oil outlet of the electromagnetic reversing valve 23 is connected to the oil inlet of the remote regulating valve 15a, the second oil outlet is connected to the oil tank 1, and the oil inlet is connected to the oil inlet of the relief valve 17a;

[0043] By controlling the power on and off of the electromagnet in the electromagnetic reversing valve 23, the following control is achieved:

[0044] 1. When the oil inlet of the electromagnetic reversing valve 23 is disconnected from the first oil outlet and the second oil outlet, the relief valve 17a is in the working state, that is, the relief valve 17a plays a pressure regulating role;

[0045] 2. When the oil inlet of the solenoid reversing valve 23 is connected to the first oil outlet, and the second oil outlet and the oil return port are connected to the oil tank 1, the remote pressure regulating valve 15a and the relief valve 17a are both in operation, and the pressure setting value of the remote pressure regulating valve 15a is lower than the pressure setting value of the relief valve 17a;

[0046] 3. When the oil inlet of the solenoid reversing valve 23 is connected to the second oil outlet, the second oil outlet is connected to the oil tank, and the first oil outlet is connected to the oil return port, the third hydraulic branch is directly connected to the oil tank 1, and the relief valve 17a and the remote pressure regulating valve 15a release pressure.

[0047] See also Figure 1 , the master cylinder hydraulic control system includes a charging valve 26, a fourth electro-hydraulic reversing valve 12 and a fifth electro-hydraulic reversing valve 13, wherein the oil inlet of the fifth electro-hydraulic reversing valve 13 is connected to the oil outlet of the oil pump 6, the second oil outlet is connected to the rodless chamber of the master cylinder C, and the oil return port is connected to the oil tank 1; the rod chamber of the master cylinder C is connected to the second oil outlet of the fourth electro-hydraulic reversing valve 12, and a relief valve 20a and a one-way sequence valve 22 are provided on the hydraulic pipeline connecting the two; the oil return port of the fourth electro-hydraulic reversing valve 12 is connected to the oil tank 1, and the first oil outlet of the fourth electro-hydraulic reversing valve 12 is connected to the rodless chamber of the fast cylinder D; the rodless chamber of the master cylinder C is also connected to the charging tank 28, and a charging valve 26 is provided on the hydraulic pipeline connecting the two;

[0048] By controlling the fourth electro-hydraulic directional control valve 12 and the fifth electro-hydraulic directional control valve 13, the following working states are achieved:

[0049] 1. When the oil inlet and the second oil outlet of the fifth electro-hydraulic reversing valve 13 are disconnected, the oil inlet and the first oil outlet of the fourth electro-hydraulic reversing valve 12 are connected, and the second oil outlet is connected to the oil return port, the rodless chamber of the fast cylinder D is connected to the oil outlet of the oil pump 6. At this time, since the inner diameter of the fast cylinder D is smaller than that of the master cylinder F, the fast cylinder D can drive the master cylinder C to move downward rapidly, creating a vacuum state in the rodless chamber of the master cylinder C, thereby prompting the filling valve 26 to open. As a result, the hydraulic oil in the filling tank 28 enters the rodless chamber of the master cylinder C;

[0050] 2. When the oil inlet and the second oil outlet of the fifth electro-hydraulic reversing valve 13 are connected, the oil inlet and the first oil outlet of the fourth electro-hydraulic reversing valve 12 are disconnected, and the first oil outlet and the second oil outlet are both connected to the oil return port, the rodless chamber of the master cylinder C is connected to the oil outlet of the oil pump 6, and the rod chamber is connected to the oil tank 1. At this time, the filling valve 26 is closed; the hydraulic oil enters the rodless chamber of the master cylinder C. Since the inner diameter of the master cylinder C is larger than that of the fast cylinder D, the hydraulic rod of the master cylinder C slowly extends;

[0051] 3. When the oil inlet and second oil outlet of the fifth electro-hydraulic reversing valve 13 are disconnected, the oil inlet and first and second oil outlets of the fourth electro-hydraulic reversing valve 12 are disconnected, and the first and second oil outlets are both connected to the oil return port, the oil inlet pipeline of the rodless chamber of the master cylinder C is disconnected, the hydraulic rod is relatively stationary, and the master cylinder C is in a pressure-maintaining state;

[0052] 4. When the oil inlet and the second oil outlet of the fifth electro-hydraulic reversing valve 13 are disconnected, the oil inlet and the second oil outlet of the fourth electro-hydraulic reversing valve 12 are connected, and the first oil outlet is connected to the oil return port, the rod chamber of the master cylinder C is connected to the oil pump 6, and the charging valve 26 is connected to the oil outlet of the oil pump 6. At this time, under the action of the one-way sequence valve 22, the hydraulic oil first enters the charging valve 26 to reversely open the charging valve 26. Then, the rod chamber of the master cylinder C is connected to the oil outlet of the oil pump 6, and the hydraulic oil enters the rod chamber of the master cylinder C, pushing the hydraulic rod to retract. At this time, the hydraulic oil in the rodless chamber of the master cylinder C flows back to the charging tank 28. As the hydraulic rod of the master cylinder C retracts, the hydraulic rod of the fast cylinder D is forced to retract. At this time, since the rodless chamber of the fast cylinder D is connected to the oil tank 1, the hydraulic oil in the rodless chamber of the fast cylinder D flows back to the oil tank 1.

[0053] In addition, a right-angle check valve 21 and an electromagnetic ball valve 25 are provided between the second oil outlet of the fifth electro-hydraulic reversing valve 13 and the rodless chamber of the master cylinder C.

[0054] See also Figure 1The hydraulic control system of the hydraulic stretching machine of the present invention also includes a hydraulic control system for a material ejecting cylinder. The hydraulic control system for the material ejecting cylinder includes an electromagnetic reversing valve 11. The oil inlet of the electromagnetic reversing valve 11 is connected to the oil outlet of the oil pump 6, and a superimposed pressure reducing valve 27 is provided on the hydraulic pipeline connecting the two. The first oil outlet of the electromagnetic reversing valve 11 is connected to the rod cavity of the material ejecting cylinder E, the second oil outlet is connected to the rodless cavity of the material ejecting cylinder E, and the oil return port is connected to the oil tank 1.

[0055] By controlling the electromagnetic reversing valve 11, the following working states can be achieved:

[0056] 1. When the oil inlet and the second oil outlet of the electromagnetic reversing valve 11 are connected, and the first oil outlet and the oil return port are connected, the rodless cavity of the ejecting cylinder E is connected to the oil outlet of the oil pump 6, and the rod cavity is connected to the oil tank 1. The hydraulic oil enters the rodless cavity of the ejecting cylinder E, pushing the hydraulic rod of the ejecting cylinder E to extend;

[0057] 2. When the oil inlet of the electromagnetic reversing valve 11 is connected to the first oil outlet, and the second oil outlet is connected to the oil return port, the rod chamber of the ejecting cylinder E is connected to the oil outlet of the oil pump 6, and the rodless chamber is connected to the oil tank 1. The hydraulic oil enters the rod chamber of the ejecting cylinder E, pushing the hydraulic rod of the ejecting cylinder E to retract;

[0058] See also Figure 1 An oil filter 2 for filtering the hydraulic oil is provided on the hydraulic pipeline between the liquid inlet of the oil pump 6 and the oil tank 1; a straight-through one-way valve 8 is provided on the hydraulic pipeline connected to the oil outlet of the oil pump 6.

[0059] See also Figure 1 A cooler 5 for cooling the hydraulic oil is provided on the hydraulic pipeline connected to the oil tank 1; in addition, a liquid level gauge 3 and an air filter 4 are provided in the oil tank 1.

[0060] See also Figure 1 , a fourth hydraulic branch connected to the oil tank 1 is provided at the oil outlet of the straight-through one-way valve 8, and an electromagnetic overflow valve 9 and an electromagnetic reversing valve 16a are provided in parallel on the fourth hydraulic branch, wherein the oil inlet of the electromagnetic overflow valve 9 is connected to the oil outlet of the straight-through one-way valve 8, and the oil outlet is connected to the oil inlet of the cooler 5; the oil inlet of the electromagnetic reversing valve 16a is connected to the oil inlet of the electromagnetic overflow valve 9, and the second oil outlet is connected to the oil inlet of the cooler 5;

[0061] By controlling the pressure rise and pressure relief of the relief valve 9 by energizing and de-energizing the electromagnetic reversing valve 16a, the following states are achieved:

[0062] When the oil inlet of the electromagnetic reversing valve 16a is connected to the first oil outlet, the second oil outlet is blocked, and the oil return port is connected to the oil tank 1 (the relief valve 9 is depressurized and the oil pump 6 is unloaded), when the oil inlet of the electromagnetic reversing valve 16a is connected to the second oil outlet, at this time, the second oil outlet is blocked; the first oil outlet and the oil return port are connected to the oil tank 1, thereby realizing the pressure starting of the relief valve 9, and the maximum pressure is the maximum set pressure of the relief valve 9.

[0063] See also Figure 1 The hydraulic control system of the hydraulic stretching machine of the present invention further includes a pressure gauge 10 provided on each hydraulic pipeline or hydraulic branch for detecting pipeline pressure.

[0064] See also Figure 1 , 18, 18a, and 18b in the figure are all pressure relays.

[0065] See also Figure 1 The following describes the secondary stretching process of the existing "filter housing stretching machine" in combination with the hydraulic control system of the hydraulic stretching machine of the utility model:

[0066] After the sheet material is fed into the stretching machine along the guide plate, the main oil cylinder C is activated, driving the movable crossbeam plate to move downward rapidly, and then driving the upper blanking die to move toward the side of the lower blanking die (the rodless cavity of the quick cylinder D is connected to the oil outlet of the oil pump 6, and the hydraulic oil enters the rodless cavity of the quick cylinder D, driving the main oil cylinder C to move downward rapidly, so that a vacuum state is generated in the rodless cavity of the main oil cylinder C, so as to prompt the filling valve 26 to open. Therefore, the hydraulic oil in the filling tank 28 enters the rodless cavity of the main oil cylinder C), until the fast-slow conversion sensing switch senses the fast-slow conversion sensing block, the main oil cylinder adjusts the downward speed, driving the movable crossbeam plate to move downward slowly (the rodless cavity of the main oil cylinder C is connected to the oil outlet of the oil pump 6; the rod cavity is connected to the oil tank 1; the hydraulic oil enters the rodless cavity of the main oil cylinder C, pushing the hydraulic rod of the main oil cylinder C to slowly descend, and the filling valve 26 is closed at this time). Since the upper blanking die is on the side closest to the lower die assembly, the upper blanking die will touch the sheet material first, and the upper blanking die and the lower blanking die will then perform blanking. After blanking is completed, the blanked sheet material will immediately fall into the blanking hole located in the lower blanking die. Subsequently, the first edge clamping cylinder generates pressure (since the first edge clamping cylinder B and the second edge clamping cylinder A are in an extended state, a certain volume of hydraulic oil is stored in the rodless cavity of the first edge clamping cylinder B, and the main oil cylinder C drives the upper die to force the lower die to continue to move downward, and the first edge clamping cylinder B generates reverse pressure to support the lower die downward, thereby playing the role of edge clamping. At this time, the third electro-hydraulic reversing valve 14a is in a power-off state, the oil inlet and the oil outlet are not connected, the first oil outlet of the electromagnetic reversing valve 23 is connected to the oil inlet of the remote pressure regulating valve 15a, and the rodless cavity of the first edge clamping cylinder B is in a power-off state). The rod cavity is not connected to the oil tank 1. The rod cavity is connected to the oil tank 1 and automatically absorbs oil. The magnitude of the reverse pressure is set by the relief valve 17a and the remote pressure regulating valve 15a. ), while the second pressure cylinder remains relatively motionless (the second electro-hydraulic reversing valve 19 and the third electro-hydraulic reversing valve 14a are both in the de-energized state, disconnecting the pipeline connection between the rodless cavity of the second pressure cylinder A and the oil pump 6. At this time, the hydraulic rod of the second pressure cylinder A is relatively stationary;), so that the blanking upper die is pressed against the pressure block, and the sheet material is clamped between the blanking upper die and the pressure block. As the main oil cylinder C continues to drive the blanking upper die downward, the sheet material will be stretched by the first stretching die. At this time, the first stretching die will serve as a stretching punch, and the blanking upper die will serve as a stretching die. The sheet material is stretched for the first time along the longitudinal direction of the first stretching die and enters the interior of the blanking lower die. When the movable crossbeam continues to descend until the blank holder force conversion sensing switch senses the blank holder force conversion sensing block, the first stretching ends immediately, and the first blank holder cylinder B releases pressure; while the second blank holder cylinder A generates pressure (the second blank holder cylinder A is in the extended state, and a certain volume of hydraulic oil is stored in the rodless cavity of the second blank holder cylinder A. The main cylinder C drives the upper die to force the lower die to continue to descend. The first blank holder cylinder B releases pressure, and the second blank holder cylinder A generates reverse pressure to support the lower die downward, thereby playing the role of blanking), so that the sheet metal is clamped between the clamping edge and the blanking block. As the main cylinder C continues to drive the blanking upper die downward, the sheet metal will be stretched by the second stretching die.The second stretching die will serve as the stretching punch, and the stretching upper die will serve as the stretching die. The sheet metal will be stretched a second time along the longitudinal direction of the second stretching die and enter the interior of the stretching upper die. When the main oil cylinder C continues to move downward until the first downward stroke sensing switch senses the first downward stroke sensing bump, the main oil cylinder C will stop moving and maintain pressure (the oil inlet pipeline of the rodless cavity of the main oil cylinder C is disconnected, and the hydraulic rod is relatively stationary. At this time, the main oil cylinder C is in a pressure-maintaining state;), when the set pressure-maintaining time is reached, the main oil cylinder C will release the pressure. After the pressure-releasing time of the main oil cylinder C reaches the set value, the main oil cylinder C will drive the movable crossbeam plate upward, and then drive the upper mold assembly upward until the first upward stroke sensing switch senses the first upward stroke sensing bump. (The rod chamber of the master cylinder C is connected to the oil pump 6, and the control port of the charging valve 26 is connected to the oil pump 6. At this time, under the action of the one-way sequence valve 22, pressurized oil enters the control port of the charging valve 26 to reversely open the charging valve 26. Then, the rod chamber of the master cylinder C is connected to the oil outlet of the oil pump 6, and pressurized oil enters the rod chamber of the master cylinder C, pushing the hydraulic rod to retract. At this time, the hydraulic oil in the rodless chamber of the master cylinder C flows back into the charging tank 28, while the hydraulic oil in the rodless chamber of the fast cylinder D flows back into the oil tank 1.) At this time, the master cylinder C stops moving, and the movable crossbeam plate returns to its initial state. At the same time, the first edge holding cylinder B and the second edge holding cylinder A will move, respectively driving the material holding block and the first stretching die upward (that is, "the rodless cavity of the first edge holding cylinder B is connected to the oil outlet of the oil pump 6, and the rod cavity of the first edge holding cylinder B is connected to the oil tank 1, therefore, the hydraulic oil enters the rodless cavity of the first edge holding cylinder B, pushing the hydraulic rod in the first edge holding cylinder B to extend;" and "the rodless cavity of the second edge holding cylinder A is connected to the oil outlet of the oil pump 6, and the rod cavity is connected to the oil tank 1, the hydraulic oil enters the rodless cavity of the second edge holding cylinder A, pushing the hydraulic rod to extend"), until the second upward stroke sensing switch senses the second upward stroke sensing block and the third ... When the switch senses the third upward stroke sensing block, the first edge holding cylinder B and the second edge holding cylinder C stop moving and unload, and the top surface of the blanking lower die, the pressure block and the first stretching die are restored to be flush; the ejection cylinder E is ejected (the rodless cavity of the ejection cylinder E is connected to the oil outlet of the oil pump 6, and the rod cavity is connected to the oil tank 1, and the hydraulic oil enters the rodless cavity of the ejection cylinder E, pushing the hydraulic rod of the ejection cylinder E to extend;), the ejection time is set at that time, and the ejection cylinder E returns (the rod cavity of the ejection cylinder E is connected to the oil outlet of the oil pump 6, and the rodless cavity is connected to the oil tank 1, and the hydraulic oil enters the rod cavity of the ejection cylinder E, pushing the hydraulic rod of the ejection cylinder E to retract;), completing a working cycle.

[0067] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A hydraulic control system for a hydraulic stretching machine, comprising an oil tank (1), an oil pump (6), a main oil cylinder hydraulic control system for controlling the operation of a main oil cylinder (C), and a pressure cylinder hydraulic control system for controlling the operation of a pressure cylinder, wherein the pressure cylinder is used to provide a pressure force for the workpiece during the stretching of the workpiece, wherein: The first blank holding cylinder (B) provides the blank holding force for the workpiece during the first stretching and forming, and the second blank holding cylinder (A) provides the blank holding force for the workpiece during the second and subsequent stretching and forming. The hydraulic control system of the edge pressing cylinder is divided into a first hydraulic control system of the edge pressing cylinder and a second hydraulic control system of the edge pressing cylinder; The second edge pressing cylinder hydraulic control system includes a hydraulic valve group for controlling the operation of the second edge pressing cylinder (A); and a shut-off valve for opening or closing the hydraulic pipeline is provided in the hydraulic pipeline connecting the hydraulic valve group and the rodless chamber of the second edge pressing cylinder (A).

2. The hydraulic control system of the hydraulic stretching machine according to claim 1, characterized in that: The hydraulic valve group includes a first electro-hydraulic reversing valve (14), wherein the oil inlet of the oil pump (6) is connected to the oil tank (1), and the oil outlet is connected to the oil inlet of the first electro-hydraulic reversing valve (14); the first oil outlet of the first electro-hydraulic reversing valve (14) is connected to the oil inlet of the stop valve, and the oil outlet of the stop valve is connected to the rodless cavity of the second pressure cylinder (A); the rod cavity of the second pressure cylinder (A) is connected to the second oil outlet of the first electro-hydraulic reversing valve (14); and the oil return port of the first electro-hydraulic reversing valve (14) is connected to the oil tank (1).

3. The hydraulic control system of the hydraulic stretching machine according to claim 2, characterized in that: The stop valve is a second electro-hydraulic reversing valve (19), the oil inlet of the second electro-hydraulic reversing valve (19) is connected to the first oil outlet of the first electro-hydraulic reversing valve (14), the second oil outlet of the second electro-hydraulic reversing valve (19) is connected to the rodless chamber of the second pressure cylinder (A), and the oil return port is connected to the oil tank (1).

4. The hydraulic control system of the hydraulic stretching machine according to claim 1, characterized in that: The second edge pressing cylinder (A) is composed of multiple groups, and the multiple groups of second edge pressing cylinders (A) operate in sequence; each group of second edge pressing cylinders (A) is controlled by an independent second edge pressing cylinder hydraulic control system; when the first edge pressing cylinder (B) operates, the stop valves in the multiple groups of second edge pressing cylinder hydraulic control systems are disconnected; when the second edge pressing cylinder (A) of the previous level operates, the stop valves in all the second edge pressing cylinder hydraulic control systems of the next level and below are disconnected.

5. The hydraulic control system of the hydraulic stretching machine according to claim 1, characterized in that: The first edge pressing cylinder hydraulic control system includes a third electro-hydraulic reversing valve (14a), the oil inlet of the third electro-hydraulic reversing valve (14a) is connected to the oil outlet of the oil pump (6), the first oil outlet is connected to the rodless cavity of the first edge pressing cylinder (B); the second oil outlet is connected to the rod cavity of the first edge pressing cylinder (B), and the return port is connected to the oil tank (1).

6. The hydraulic control system of the hydraulic stretching machine according to claim 1, characterized in that: The master cylinder hydraulic control system further includes a fast cylinder (D).

7. The hydraulic control system of the hydraulic stretching machine according to claim 6, characterized in that: The master cylinder hydraulic control system includes a filling valve (26), a fourth electro-hydraulic reversing valve (12) and a fifth electro-hydraulic reversing valve (13), wherein the oil inlet of the fifth electro-hydraulic reversing valve (13) is connected to the oil outlet of the oil pump (6), the second oil outlet is connected to the rodless cavity of the master cylinder (C), and the oil return port is connected to the oil tank (1); the rod cavity of the master cylinder (C) is connected to the second oil outlet of the fourth electro-hydraulic reversing valve (12), and an overflow valve (20a) and a one-way sequence valve (22) are provided on the hydraulic pipeline connecting the two; the oil return port of the fourth electro-hydraulic reversing valve (12) is connected to the oil tank (1), and the first oil outlet of the fourth electro-hydraulic reversing valve (12) is connected to the rodless cavity of the fast cylinder (D); the rodless cavity of the master cylinder (C) is also connected to the filling tank (28), and a filling valve (26) is provided on the hydraulic pipeline connecting the two.

8. The hydraulic control system of the hydraulic stretching machine according to claim 1, characterized in that: The main oil cylinder hydraulic control system also includes a lifting cylinder (E) and a lifting cylinder hydraulic control system for controlling the operation of the lifting cylinder (E), wherein the lifting cylinder hydraulic control system includes an electromagnetic reversing valve (11), the oil inlet of the electromagnetic reversing valve (11) is connected to the oil outlet of the oil pump (6), and a superimposed pressure reducing valve (27) is provided on the hydraulic pipeline connecting the two; the first oil outlet of the electromagnetic reversing valve (11) is connected to the rod cavity of the lifting cylinder (E), the second oil outlet is connected to the rodless cavity of the lifting cylinder (E), and the oil return port is connected to the oil tank (1).

9. The hydraulic control system of the hydraulic stretching machine according to claim 2, characterized in that: An oil filter (2) is provided on the hydraulic pipeline between the oil inlet of the oil pump (6) and the oil tank (1).

10. The hydraulic control system of the hydraulic stretching machine according to claim 2, characterized in that: A one-way valve (8) is provided on the hydraulic pipeline connected to the oil outlet of the oil pump (6).

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