Hydraulic system for controlling BMC pressing device of injection molding machine

Abstract

The invention relates to the technical field of injection molding machines, and particularly discloses a hydraulic system for controlling a BMC (bulk molding compound) material pressing device of an injection molding machine, which comprises an oil tank, a first power unit, a second power unit, a first reversing valve, a second reversing valve and a material pressing oil cylinder, the first power unit or the second power unit can be decided to supply liquid to the material pressing oil cylinder through the first reversing valve, when the material pressing oil cylinder conducts large-flow actions such as ascending or descending, the first power unit with large power can supply liquid to the material pressing oil cylinder, and when the material pressing oil cylinder conducts pressure maintaining small-flow actions, the second power unit can supply liquid to the material pressing oil cylinder. Due to the fact that the power is small, the energy consumption is low, the cost can be saved, when the second power unit conducts pressure maintaining liquid supply, the first power unit can still supply liquid for other actions of the injection molding machine, and the overall efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of injection molding machines, in particular to a hydraulic system for controlling a BMC material pressing device of an injection molding machine. Background Art

[0002] BMC raw material injection molding machine is a special injection molding equipment for molding BMC plastic products. With the continuous improvement of industrial automation level, the requirements for the performance of injection molding machines are getting higher and higher, especially in improving production efficiency, ensuring product quality and ensuring operation safety.

[0003] In order to control the pressing device, the BMC raw material injection molding machines currently on the market usually add an additional hydraulic power unit with a larger flow rate to control the action of the pressing device based on the hydraulic power unit of the standard injection molding machine. However, there are the following problems: first, the cost of using a large-flow hydraulic power unit is relatively high, and during the pressure-maintaining process of the pressing cylinder, the required flow rate is relatively small. The use of a large-flow hydraulic power unit will cause energy waste, and the use of a small-flow hydraulic power unit cannot meet the speed requirements of the rising and falling actions of the pressing cylinder. Summary of the invention

[0004] The present invention is made in consideration of the above-mentioned problems. The purpose of the invention is to provide a hydraulic system for controlling the BMC pressing device of an injection molding machine. It only requires the addition of a set of small-flow hydraulic power units, and cooperates with the original power unit of the injection molding machine to supply fluid to the pressing cylinder, which can not only meet the needs of the pressing cylinder, but also save costs.

[0005] To achieve the above object, the present invention provides a hydraulic system for controlling a BMC pressing device of an injection molding machine, comprising an oil tank, a first power unit, a second power unit, a first reversing valve, a second reversing valve and a pressing oil cylinder, wherein the oil inlets of the first power unit and the second power unit are both connected to the oil tank;

[0006] The first reversing valve is provided with a first oil inlet, a second oil inlet and a first oil outlet, the first oil outlet is communicated with the first oil inlet or the second oil inlet, the oil outlet of the first power unit is communicated with the first oil inlet, and the oil outlet of the second power unit is communicated with the second oil inlet;

[0007] The second reversing valve is provided with a third oil inlet, a first oil return port, a first variable oil port and a second variable oil port. When the third oil inlet is connected to the first variable oil port, the first oil return port is connected to the second variable oil port. When the third oil inlet is connected to the second variable oil port, the first oil return port is connected to the first variable oil port, the first oil outlet is connected to the third oil inlet, the first variable oil port is connected to the rodless chamber of the pressing cylinder, and the second variable oil port is connected to the rod chamber of the pressing cylinder.

[0008] The power of the second power unit is smaller than the power of the first power unit.

[0009] According to the above-mentioned hydraulic system for controlling the BMC pressing device of an injection molding machine, a first one-way valve is provided between the first variable oil port and the rodless chamber of the pressing cylinder, and the opening of the first one-way valve is toward the rodless chamber of the pressing cylinder, and a second one-way valve is provided between the second variable oil port and the rod chamber of the pressing cylinder, and the opening of the second one-way valve is toward the rod chamber of the pressing cylinder.

[0010] According to the above-mentioned hydraulic system for controlling the BMC pressing device of an injection molding machine, it also includes a first open pipe, one end of the first open pipe is connected to the first variable oil port, and the other end of the first open pipe is connected to the second one-way valve. When oil flows out of the first variable oil port, the second one-way valve can be opened through the first open pipe.

[0011] According to the above-mentioned hydraulic system for controlling the BMC pressing device of an injection molding machine, it also includes a second open pipe, one end of the second open pipe is connected to the second variable oil port, and the other end of the second open pipe is connected to the first one-way valve. When oil flows out of the second variable oil port, the first one-way valve can be opened through the second open pipe.

[0012] According to the above-mentioned hydraulic system for controlling the BMC pressing device of the injection molding machine, it also includes a differential valve, and the differential valve is provided with a third variable oil port, a fourth variable oil port and a second oil return port. The fourth variable oil port can be connected to the third variable oil port or the second oil return port. The third variable oil port is connected to the oil port of the second one-way valve close to the rod chamber of the pressing cylinder, the fourth variable oil port is connected to the rod chamber of the pressing cylinder, and the second oil return port is connected to the first one-way valve and the pipeline between the rodless chamber of the pressing cylinder.

[0013] According to the above-mentioned hydraulic system for controlling the BMC pressing device of an injection molding machine, a first electromagnet is provided on the differential valve. When the first electromagnet is energized, the fourth variable oil port is connected to the second oil return port. When the first electromagnet is de-energized, the fourth variable oil port is connected to the third variable oil port.

[0014] According to the above-mentioned hydraulic system for controlling the BMC pressing device of the injection molding machine, it also includes a first overflow valve, a first pipeline is provided between the third variable oil port and the oil port of the second one-way valve, and the first overflow valve is connected to the first pipeline.

[0015] The hydraulic system for controlling the BMC pressing device of an injection molding machine as described above also includes an electrically controlled one-way shut-off valve, which is located between the first one-way valve and the rodless chamber of the pressing cylinder, and the electrically controlled one-way shut-off valve can receive a switching signal from the protective door of the injection molding machine and can block the first one-way valve and the rodless chamber of the pressing cylinder.

[0016] According to the above-mentioned hydraulic system for controlling the BMC pressing device of the injection molding machine, it also includes a second overflow valve, a second pipeline is provided between the first power unit and the first oil inlet, and the second overflow valve is connected to the second pipeline.

[0017] According to the above-mentioned hydraulic system for controlling the BMC pressing device of the injection molding machine, it also includes a third overflow valve, a third pipeline is provided between the second power unit and the second oil inlet, and the third overflow valve is connected to the third pipeline.

[0018] The present invention has the following beneficial effects:

[0019] 1. A second power unit is added, and the first reversing valve can be used to determine whether the first power unit or the second power unit supplies fluid to the press cylinder. When the press cylinder is performing large flow actions such as rising or falling, the first power unit with larger power can supply fluid to it. When the press cylinder is performing pressure-maintaining and small flow work, the second power unit can supply fluid to it. Due to its small power, its energy consumption is low, which can save costs. When the second power unit is maintaining pressure and supplying fluid, the first power unit can still supply fluid for other actions of the injection molding machine, thereby improving overall efficiency.

[0020] 2. An electric one-way shut-off valve is installed. The downward pressure action of the pressure cylinder has a higher risk factor. The pressure cylinder can only start to move when the protective door is fully closed, which improves safety performance;

[0021] 3. When the first power unit or the second power unit supplies oil to the rodless chamber of the press cylinder, the hydraulic oil in the rod chamber can be replenished to the rodless chamber through the differential valve, so differential rise can be achieved to improve efficiency;

[0022] 4. A first one-way valve is provided between the first variable oil port and the rodless chamber of the press cylinder, and a second one-way valve is provided between the second variable oil port and the rod chamber of the press cylinder. The oil pressure in the oil inlet chamber can be maintained by the first one-way valve and the second one-way valve;

[0023] 5. A first overflow valve is provided on one side of the first pipeline between the third variable oil port and the second one-way valve, which can prevent the oil return from being unsmooth due to blockage and avoid safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the overall oil circuit of the embodiment.

[0025] In the figure:

[0026] 1. Oil tank; 2. First power unit; 3. Second power unit; 4. First reversing valve; 5. Second reversing valve; 6. Pressing cylinder; 7. First non-return valve; 8. Second non-return valve; 9. First opening pipe; 10. Second opening pipe; 11. Differential valve; 12. First overflow valve; 13. Electric non-return shut-off valve; 14. Second overflow valve; 15. Third overflow valve; 16. Protective door. DETAILED DESCRIPTION

[0027] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0028] like Figure 1 As shown, a hydraulic system for controlling a BMC pressing device of an injection molding machine includes an oil tank 1, a first power unit 2, a second power unit 3, a first reversing valve 4, a second reversing valve 5 and a pressing cylinder 6.

[0029] Among them, the oil inlets of the first power unit 2 and the second power unit 3 are both connected to the oil tank 1, and an oil pipe is inserted into the oil inlet. Liquid can be pumped out of the oil tank 1 through the oil pipe. A filter can be set at one end of the oil pipe to prevent impurities from entering the power unit.

[0030] Specifically, the first reversing valve 4 is provided with a first oil inlet, a second oil inlet and a first oil outlet, the first oil outlet is connected to the first oil inlet or the second oil inlet, the oil outlet of the first power unit 2 is connected to the first oil inlet, the oil outlet of the second power unit 3 is connected to the second oil inlet, and a second electromagnet is also provided on the first reversing valve 4. When the piston rod of the pressing cylinder 6 is rising or falling, the second electromagnet loses power, the first oil inlet is connected to the first oil outlet, the pressing cylinder 6 is supplied with oil through the first power unit 2, and the pressing cylinder 6 is When holding pressure, the second electromagnet is energized, the second oil inlet is connected to the second oil outlet, and the pressing cylinder 6 is supplied with oil through the second power unit 3, so that the first power unit 2 and the second power unit 3 can be switched between different states. Since the power of the second power unit 3 is less than that of the first power unit 2, the use of the second power unit 3 in the holding pressure stage can reduce energy consumption and save costs. When the second power unit 3 is used for fluid supply, the first power unit 2 can provide hydraulic oil for the movement of other parts of the injection molding machine, thereby improving the overall efficiency.

[0031] Specifically, the second reversing valve 5 is provided with a third oil inlet, a first oil return port, a first variable oil port and a second variable oil port. When the third oil inlet is connected to the first variable oil port, the first oil return port is connected to the second variable oil port. When the third oil inlet is connected to the second variable oil port, the first oil return port is connected to the first variable oil port, the first oil outlet is connected to the third oil inlet, the first variable oil port is connected to the rodless cavity of the pressing cylinder 6, and the second variable oil port is connected to the rod cavity of the pressing cylinder 6. In this embodiment, the first reversing valve 4 is essentially a two-position four-way valve, and the second reversing valve 5 is essentially a three-position four-way valve. The second reversing valve 5 is also provided with a third electromagnet and a fourth electromagnet. When the third electromagnet is energized, the third oil inlet is connected with the second variable oil port, which supplies oil to the rod chamber of the pressing cylinder 6 through the second variable oil port, and its piston rod descends, while the hydraulic oil in the rodless chamber of the pressing cylinder 6 is returned through the first variable oil port and the first oil return port, and the returned oil is returned to the oil tank 1, and when the fourth electromagnet is energized, the third oil inlet is connected with the first variable oil port, which supplies oil to the rodless chamber of the pressing cylinder 6 through the first variable oil port, and its piston rod rises, and the hydraulic oil in the rod chamber of the pressing cylinder 6 is returned through the second variable oil port and the first oil return port, and when the third and fourth electromagnets are both de-energized, they are in the middle position, and the piston rod of the pressing cylinder 6 remains stationary.

[0032] In this embodiment, there is at least one pressing cylinder 6, and there may be more than one pressing cylinder 6, and the number is not limited.

[0033] In order to maintain the pressure of the rodless chamber and the rod chamber of the pressing oil cylinder 6 when oil is supplied to the rodless chamber, a first one-way valve 7 is provided between the first variable oil port and the rodless chamber of the pressing oil cylinder 6, and the opening of the first one-way valve 7 is toward the rodless chamber of the pressing oil cylinder 6. When oil is supplied to the rodless chamber through the first variable oil port, the hydraulic oil can only flow toward the rodless chamber of the pressing oil cylinder 6 and cannot flow back, thereby ensuring the stability of the oil pressure in the rodless chamber of the pressing oil cylinder 6, and a second one-way valve 8 is provided between the second variable oil port and the rod chamber of the pressing oil cylinder 6, and the opening of the second one-way valve 8 is toward the rod chamber of the pressing oil cylinder 6. When oil is supplied to the rod chamber of the pressing oil cylinder 6 through the second variable oil port, the hydraulic oil can only flow to the rod chamber of the pressing oil cylinder 6 and cannot flow from the rod chamber of the pressing oil cylinder 6 to the second variable oil port, thereby ensuring the stability of the oil pressure in the rod chamber of the pressing oil cylinder 6.

[0034] In order to prevent the second one-way valve 8 from hindering the oil return from the rod chamber of the pressing cylinder 6, a first opening pipe 9 is also included. One end of the first opening pipe 9 is connected to the first variable oil port, and the other end of the first opening pipe 9 is connected to the second one-way valve 8. When the first variable oil port discharges oil, the second one-way valve 8 can be opened through the first opening pipe 9. When oil is supplied to the rodless chamber of the pressing cylinder 6 through the first variable oil port, a part of the hydraulic oil will flow into the first opening pipe 9, and the second one-way valve 8 is opened by using the hydraulic oil, so that the hydraulic oil in the rod chamber of the pressing cylinder 6 can return through the second one-way valve 8.

[0035] In order to prevent the first one-way valve 7 from hindering the oil return from the rodless chamber of the pressing cylinder 6, a second opening pipe 10 is also included. One end of the second opening pipe 10 is connected to the second variable oil port, and the other end of the second opening pipe 10 is connected to the first one-way valve 7. When oil is discharged from the second variable oil port, the first one-way valve 7 can be opened through the second opening pipe 10. When oil is supplied to the rod chamber of the pressing cylinder 6 through the second variable oil port, a part of the hydraulic oil will flow into the second opening pipe 10. The hydraulic oil is used to open the first one-way valve 7, so that the hydraulic oil in the rodless chamber of the pressing cylinder 6 can return through the first one-way valve 7.

[0036] In order to improve the oil inlet efficiency of the rodless chamber of the material pressing cylinder 6, and thus improve the material pressing efficiency, a differential valve 11 is also included, on which a third variable oil port, a fourth variable oil port and a second oil return port are provided, the fourth variable oil port can be communicated with the third variable oil port or the second oil return port, the third variable oil port is communicated with the oil port of the second one-way valve 8 close to the rod chamber of the material pressing cylinder 6, the fourth variable oil port is communicated with the rod chamber of the material pressing cylinder 6, the second oil return port is communicated with the first one-way valve 7 and the pipeline between the rodless chamber of the material pressing cylinder 6, Specifically, a first electromagnet is provided on the differential valve 11. When the first electromagnet is energized, the fourth variable oil port is connected to the second oil return port. When the first electromagnet is de-energized, the fourth variable oil port is connected to the third variable oil port. When the first one-way valve 7 supplies oil to the rodless chamber of the pressing cylinder 6, the first electromagnet is energized, and the hydraulic oil in the rod chamber of the pressing cylinder 6 flows back into the rodless chamber of the pressing cylinder 6 through the fourth variable oil port and the second oil return port, thereby realizing differential oil return and accelerating the operating efficiency of the pressing cylinder 6.

[0037] In order to limit the maximum pressure value during the downward pressing process of the pressing cylinder 6, a first overflow valve 12 is also included. A first pipeline is arranged between the third variable oil port and the oil port of the second one-way valve 8. The first overflow valve 12 is connected to the first pipeline. When the pressing cylinder 6 is pressed downward, oil is supplied to the rod chamber of the pressing cylinder 6 through the second one-way valve 8, and the oil enters the rod chamber of the pressing cylinder 6 through the third variable oil port and the fourth variable oil port. In this process, if the oil pressure in the rod chamber of the pressing cylinder 6 is too high, it may easily lead to dangerous accidents such as explosion. Therefore, when the oil pressure is too high, the oil may overflow through the first overflow valve 12.

[0038] In order to avoid personal injury during the operation of the pressing cylinder 6, an electrically controlled one-way shut-off valve 13 is also included. The electrically controlled one-way shut-off valve 13 is located between the first one-way valve 7 and the rodless cavity of the pressing cylinder 6. A protective door 16 is provided on the injection molding machine. In the present embodiment, a position sensor is provided on the protective door 16. When the protective door 16 is not closed in place, the electrically controlled one-way shut-off valve 13 can disconnect the pipeline between the first one-way valve 7 and the rodless cavity of the pressing cylinder 6, so that the pressing cylinder 6 cannot perform normal downward pressure work to avoid causing harm to the human body. When the protective door 16 is closed in place, the electrically controlled one-way shut-off valve 13 can receive the signal of the position sensor. At this time, the electromagnet on the electrically controlled one-way shut-off valve 13 is energized, and the electrically controlled one-way shut-off valve 13 is opened, so that the first one-way valve 7 is normally connected to the pressing cylinder 6.

[0039] In order to avoid excessive oil pressure between the first power unit 2 and the first oil inlet, a second overflow valve 14 is also included. A second pipeline is provided between the first power unit 2 and the first oil inlet. The second overflow valve 14 is connected to the second pipeline. When the pressure is too high, it can overflow through the second overflow valve 14 to protect the first power unit 2.

[0040] In order to avoid excessive oil pressure between the second power unit 3 and the second oil inlet, a third overflow valve 15 is also included. A third pipeline is provided between the second power unit 3 and the second oil inlet. The third overflow valve 15 is connected to the third pipeline. When the pressure is too high, it can overflow through the third overflow valve 15 to protect the second power unit 3.

[0041] Of course, pressure gauges may also be provided on multiple oil circuits to monitor the pressure conditions on each oil circuit in real time.

[0042] The technical solution of the present invention is described in detail above in conjunction with the accompanying drawings, and the described embodiments are used to help understand the concept of the present invention. The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art of the invention may make various modifications or supplements to the described specific embodiments or replace them in a similar manner, but they will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims.

[0043] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0044] In addition, in the present invention, descriptions such as "first", "second", "one", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0045] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A hydraulic system for controlling a BMC pressing device of an injection molding machine, characterized in that: It includes an oil tank, a first power unit, a second power unit, a first reversing valve, a second reversing valve and a pressing oil cylinder, and the oil inlets of the first power unit and the second power unit are both connected to the oil tank; The first reversing valve is provided with a first oil inlet, a second oil inlet and a first oil outlet, the first oil outlet is communicated with the first oil inlet or the second oil inlet, the oil outlet of the first power unit is communicated with the first oil inlet, and the oil outlet of the second power unit is communicated with the second oil inlet; The second reversing valve is provided with a third oil inlet, a first oil return port, a first variable oil port and a second variable oil port. When the third oil inlet is connected to the first variable oil port, the first oil return port is connected to the second variable oil port. When the third oil inlet is connected to the second variable oil port, the first oil return port is connected to the first variable oil port, the first oil outlet is connected to the third oil inlet, the first variable oil port is connected to the rodless chamber of the pressing cylinder, and the second variable oil port is connected to the rod chamber of the pressing cylinder. The power of the second power unit is smaller than the power of the first power unit.

2. A hydraulic system for controlling a BMC pressing device of an injection molding machine according to claim 1, characterized in that: A first one-way valve is provided between the first variable oil port and the rodless chamber of the material pressing cylinder, and the opening of the first one-way valve faces the rodless chamber of the material pressing cylinder. A second one-way valve is provided between the second variable oil port and the rod chamber of the material pressing cylinder, and the opening of the second one-way valve faces the rod chamber of the material pressing cylinder.

3. A hydraulic system for controlling a BMC pressing device of an injection molding machine according to claim 2, characterized in that: It also includes a first open pipeline, one end of which is connected to the first variable oil port, and the other end of the first open pipeline is connected to the second one-way valve. When oil flows out of the first variable oil port, the second one-way valve can be opened through the first open pipeline.

4. A hydraulic system for controlling a BMC pressing device of an injection molding machine according to claim 2, characterized in that: It also includes a second open pipeline, one end of which is connected to the second variable oil port, and the other end of the second open pipeline is connected to the first one-way valve. When oil flows out of the second variable oil port, the first one-way valve can be opened through the second open pipeline.

5. A hydraulic system for controlling a BMC pressing device of an injection molding machine according to claim 2, characterized in that: It also includes a differential valve, which is provided with a third variable oil port, a fourth variable oil port and a second oil return port. The fourth variable oil port can be communicated with the third variable oil port or the second oil return port. The third variable oil port is communicated with the oil port of the second one-way valve close to the rod chamber of the pressing cylinder, the fourth variable oil port is communicated with the rod chamber of the pressing cylinder, and the second oil return port is communicated with the first one-way valve and a pipeline between the rodless chamber of the pressing cylinder.

6. A hydraulic system for controlling a BMC pressing device of an injection molding machine according to claim 5, characterized in that: The differential valve is provided with a first electromagnet. When the first electromagnet is energized, the fourth variable oil port is communicated with the second oil return port. When the first electromagnet is de-energized, the fourth variable oil port is communicated with the third variable oil port.

7. A hydraulic system for controlling a BMC pressing device of an injection molding machine according to claim 5, characterized in that: It also includes a first overflow valve, a first pipeline is arranged between the third variable oil port and the oil port of the second one-way valve, and the first overflow valve is communicated with the first pipeline.

8. A hydraulic system for controlling a BMC pressing device of an injection molding machine according to claim 2, characterized in that: It also includes an electrically controlled one-way shut-off valve, which is located between the first one-way valve and the rodless chamber of the pressure cylinder. The electrically controlled one-way shut-off valve can receive a switch signal from the protective door of the injection molding machine and can block the first one-way valve and the rodless chamber of the pressure cylinder.

9. A hydraulic system for controlling a BMC pressing device of an injection molding machine according to claim 1, characterized in that: It also includes a second overflow valve, a second pipeline is provided between the first power unit and the first oil inlet, and the second overflow valve is connected to the second pipeline.

10. A hydraulic system for controlling a BMC pressing device of an injection molding machine according to claim 1, characterized in that: It also includes a third overflow valve. A third pipeline is provided between the second power unit and the second oil inlet. The third overflow valve is connected to the third pipeline.

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