Pre-plasticizing oil supplementing control oil way for PET product electric melt adhesive structure

Abstract

The utility model relates to a pre-plasticizing oil supplementing control oil way for an electric melt adhesive structure of a PET product, and belongs to the technical field of injection molding. The oil inlet pipeline and the oil return pipeline are connected with an oil tank, an oil pump and a servo motor are arranged on the oil inlet pipeline, an overflow valve is arranged between the oil inlet pipeline and the oil return pipeline, a pressure type cartridge valve is arranged on the oil return pipeline, and the pressure type cartridge valve is located between the overflow valve and the oil tank. The three-position four-way reversing valve set comprises a three-position four-way reversing valve, the three-position four-way reversing valve is provided with a first output oil port and a second output oil port, the middle position of the three-position four-way reversing valve and the first output oil port are communicated with the oil return port, and the left position and the right position of the three-position four-way reversing valve and the four oil ports are communicated in a one-to-one correspondence mode and are opposite. The second output oil port is communicated with a rod cavity of the injection oil cylinder and an oil return pipeline and is provided with a cartridge valve, and the first output oil port is communicated with a rodless cavity of the injection oil cylinder. The oil way has the effect of supplementing oil for the rodless cavity of the injection oil cylinder.

Description

Technical Field

[0001] The present application relates to the field of injection molding, and in particular to a pre-plasticizing oil replenishment control oil circuit for an electric melt adhesive structure of a PET product. Background Art

[0002] Injection molding machine is also known as injection molding machine or injection machine. It is the main molding equipment that uses plastic molding molds to make plastic products of various shapes from thermoplastics or thermosetting plastics. The injection molding machine can heat the plastic and apply high pressure to the molten plastic to make it ejected and fill the mold cavity. The injection molding machine includes an injection system and a hydraulic transmission system, wherein the injection system is composed of a plasticizing device and a power transmission device, and the plasticizing device of the screw injection molding machine is mainly composed of a feeding device, a barrel, a screw, a glue assembly, and a nozzle. The power transmission device includes an injection cylinder, an injection seat moving cylinder, and a screw drive device (melting motor). The feeding device feeds the plastic particles into the barrel, and the screw rotates in the barrel, driving the plastic particles to continuously move toward the nozzle into the storage chamber. The plastic particles are heated and melted during the movement to complete the hydraulic melting. The rotation of the screw is realized by the melting motor, and the injection of the injection molding machine is realized by the injection cylinder. The injection cylinder drives the screw forward to eject the molten plastic. After the injection is completed, the screw continues to rotate to store the material.

[0003] When a conventional injection molding machine is hydraulically melting glue, the rotation of the motor causes the molten material to continuously flow to the nozzle, and at the same time generates a backward force on the screw, that is, the piston rod of the injection cylinder extends backward. At this time, a reaction force is needed to prevent the screw from retreating, thereby maintaining the material storage pressure. At the same time, the return oil of the motor can enter the barless cavity of the injection cylinder through the injection valve to achieve oil replenishment and prevent vacuum in the cylinder, which will not affect the normal operation of the material storage process.

[0004] In order to save energy, injection molding parts can now use electric glue melting instead of hydraulic glue melting, and the motor drives the screw to rotate. When electric glue melting is used, since there is no return oil from the hydraulic motor to replenish the oil, a separate oil replenishing motor is generally required to replenish the oil, which is more complicated in structure and more costly. Utility Model Content

[0005] In order to complete the oil replenishment of the rodless chamber of the injection cylinder without adding an oil replenishment motor, the present application provides a pre-plasticizing oil replenishment control oil circuit for an electric melt adhesive structure of a PET product.

[0006] The present application provides a pre-plasticizing oil replenishment control oil circuit for an electric melt adhesive structure of a PET product, which adopts the following technical solution:

[0007] A pre-plasticizing oil replenishment control oil circuit for an electric melt adhesive structure of a PET product, comprising an injection cylinder, an oil tank, an oil inlet pipeline and an oil return pipeline connected to the oil tank, and a three-position four-way reversing valve group, wherein an oil pump and a servo motor are arranged on the oil inlet pipeline for pumping the oil in the oil tank into the oil inlet pipeline, an overflow valve is arranged between the oil inlet pipeline and the oil return pipeline and the two are connected through the overflow valve, a pressure-type cartridge valve is arranged on the oil return pipeline, and the pressure-type cartridge valve is located between the overflow valve and the oil tank, the three-position four-way reversing valve group comprises a three-position four-way reversing valve, the three-position four-way reversing valve is provided with an oil inlet port, an oil return port, a first oil output port and a second oil output port, and the three-position four-way reversing valve is located When in the middle position, the first oil output port is connected with the oil return port. When the three-position four-way reversing valve is in the left position, the first oil output port is connected with the oil return port, and the second oil output port is connected with the oil inlet port. When the three-position four-way reversing valve is in the right position, the corresponding connections are opposite to those in the left position. The oil inlet pipeline and the oil return pipeline are respectively connected to the oil inlet and the oil return port of the three-position four-way reversing valve. The second oil output port is connected to the rod chamber of the injection cylinder, and a branch of the oil circuit between the second oil output port and the injection cylinder is connected to the oil return pipeline and is provided with a cartridge valve. The first oil output port is connected to the rodless chamber of the injection cylinder. When the piston rod of the injection cylinder extends, the screw retreats.

[0008] By adopting the above technical scheme, this oil circuit does not need to add an additional power unit. When the injection molding machine performs the material storage action, there is no additional return oil to replenish the barless chamber of the injection cylinder because it is an electric melt adhesive. By setting a pressure-type cartridge valve before the return oil in the return oil pipeline enters the oil tank, a return oil back pressure is provided through the pressure-type cartridge valve. At the same time, the middle position of the three-position four-way reversing valve corresponds to the material storage action. At this time, the return oil can directly enter the barless chamber of the injection cylinder through the three-position four-way reversing valve before overcoming the spring pressure of the pressure-type cartridge valve to achieve oil replenishment, so that it is not easy to pull a vacuum when the injection cylinder moves. At the same time, a branch is separated from the oil circuit between the second output oil port and the injection cylinder to connect the return oil pipeline and set a cartridge valve. When the three-position four-way reversing valve is in the middle position, the rod chamber of the injection cylinder can return oil through the branch to achieve material storage action. At the same time, the cartridge valve provides back pressure for the material storage action.

[0009] Optionally, the three-position four-way reversing valve group is a three-position four-way electro-hydraulic reversing valve, which includes a three-position four-way solenoid reversing valve and a three-position four-way hydraulically controlled reversing valve. The three-position four-way hydraulically controlled reversing valve is provided with an oil inlet, an oil return port, a first oil output port and a second oil output port. When the three-position four-way hydraulically controlled reversing valve is in a middle position, the first oil output port is connected with the oil return port. When the three-position four-way hydraulically controlled reversing valve is in a left position, the first oil output port is connected with the oil return port, and the second oil output port is connected with the oil inlet. When the three-position four-way hydraulically controlled reversing valve is in a right position, the corresponding connections are opposite to those in the left position. The three-position four-way solenoid reversing valve is provided with a control oil inlet, a control oil return port, a first control oil outlet and a second control oil outlet. When the three-position four-way solenoid reversing valve is in the middle position, the first control oil outlet and the second control oil outlet are both connected to the oil return port. When the three-position four-way solenoid reversing valve is in the left position, the first control oil outlet is connected to the oil return port, and the second control oil outlet is connected to the oil inlet. When the three-position four-way solenoid reversing valve is in the right position, the corresponding connections are opposite to those in the left position. The first control oil outlet and the second control oil outlet are respectively connected to the left and right hydraulic control ports of the three-position four-way hydraulically controlled reversing valve.

[0010] By adopting the above technical solution, the three-position four-way directional valve group adopts a three-position four-way electro-hydraulic directional valve, so that a small-capacity three-position four-way electromagnetic directional valve can be used to control a large-diameter three-position four-way hydraulically controlled directional valve, which reduces the difficulty of switching and makes the operation more stable.

[0011] Optionally, it also includes a seat-shifting cylinder and a seat-use three-position four-way solenoid reversing valve, the seat-use three-position four-way solenoid reversing valve being provided with four oil ports and respectively connected to the oil inlet pipeline, the oil return pipeline, the rod chamber and the rodless chamber of the seat-shifting cylinder. When the seat-use three-position four-way solenoid reversing valve is in the middle position, the four oil ports of the seat-use three-position four-way solenoid reversing valve are not connected. When the seat-use three-position four-way solenoid reversing valve is in the left position, the oil inlet pipeline is connected to the rodless chamber of the seat-shifting cylinder, and the oil return pipeline is connected to the rod chamber of the seat-shifting cylinder. When the seat-use three-position four-way solenoid reversing valve is in the right position, the oil ports corresponding to the left position are swapped. A hydraulically controlled one-way valve is provided between the seat-use three-position four-way solenoid reversing valve and the rod chamber of the seat-shifting cylinder to control the unidirectional flow of oil into the seat-shifting cylinder. The hydraulically controlled end of the hydraulically controlled one-way valve is connected to the rodless chamber of the seat-shifting cylinder, and the seat-shifting cylinder pulls the injection seat to abut the nozzle.

[0012] By adopting the above technical scheme, the seat movement process of the injection seat is controlled by the three-position four-way electromagnetic reversing valve for the seat, and then a hydraulically controlled one-way valve is provided between the three-position four-way electromagnetic reversing valve for the seat and the rod chamber of the seat movement cylinder. This will not affect the normal control of the seat movement process of the injection seat by the three-position four-way electromagnetic reversing valve for the seat, and can maintain the abutment between the injection seat and the nozzle. It is not easy to cause glue leakage caused by loose abutment due to oil circuit problems. Compared with setting a complicated hydraulic self-locking nozzle structure at the nozzle, the method is simpler and more effective.

[0013] Optionally, the overflow valve is a two-stage electromagnetic overflow valve.

[0014] Optionally, a cooler is provided in the oil return pipeline between the pressure-type cartridge valve and the oil tank.

[0015] By adopting the above technical solution, the oil temperature is lowered by the cooler to ensure the normal operation of the system. Due to the particularity of the injection molding machine that needs to heat the plastic particles, the oil in the oil circuit is prone to continuous temperature increase. The cooler can well maintain the stability of the oil temperature in the oil circuit.

[0016] Optionally, it also includes a pressure regulating valve and a two-position two-way solenoid reversing valve. The oil inlet circuit of the cartridge valve is divided into two control branches which are respectively connected to the hydraulic control end of the cartridge valve and an oil port of the two-position two-way solenoid reversing valve. The other oil port of the two-position two-way solenoid reversing valve is connected to the return oil pipeline after passing through the pressure regulating valve. The left position of the two-position two-way solenoid reversing valve is directly connected, while the right position is provided with a one-way valve structure and flows into the control branch in one direction.

[0017] Optionally, the return oil of the injection molding machine when opening and closing the mold is connected to the oil return pipeline.

[0018] By adopting the above technical scheme, when the injection molding machine finishes cooling and the mold is opened, the return oil of the mold opening and closing can be used to replenish the rodless cavity of the injection cylinder. The injection cylinder return oil and the mold opening and closing oil return during material storage are combined, so that the mold opening and closing and material storage can be synchronized.

[0019] To sum up, in the case of not adding an additional power unit, when the injection molding machine performs the material storage action, due to the use of electric melt adhesive, there is no additional return oil to replenish the barless chamber of the injection cylinder. By setting a pressure-type cartridge valve before the return oil in the return oil pipeline enters the oil tank, a return oil back pressure is provided through the pressure-type cartridge valve. At the same time, the middle position of the three-position four-way reversing valve corresponds to the material storage action. At this time, the return oil can directly enter the barless chamber of the injection cylinder through the three-position four-way reversing valve before overcoming the spring pressure of the pressure-type cartridge valve to achieve oil replenishment, so that it is not easy to pull a vacuum when the injection cylinder moves. At the same time, a branch is separated from the oil circuit between the second output oil port and the injection cylinder to connect the return oil pipeline and set a cartridge valve. When the three-position four-way reversing valve is in the middle position, the rod chamber of the injection cylinder can return oil through the branch to achieve material storage action. At the same time, the cartridge valve provides back pressure for the material storage action. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 : is the oil circuit diagram of the pre-plasticizing oil replenishment control oil circuit in the embodiment of the present application;

[0021] Figure 2 yes Figure 1 Partial oil circuit diagram in.

[0022] Explanation of the reference numerals: 1, injection cylinder; 2, seat shift cylinder; 3, oil tank; 4, oil inlet pipeline; 5, oil return pipeline; 6, three-position four-way solenoid reversing valve for seat; 61, hydraulically controlled one-way valve; 7, three-position four-way electro-hydraulic reversing valve; 71, three-position four-way solenoid reversing valve; 711, control oil inlet; 712, control oil return port; 713, first control oil outlet; 714, second control oil outlet; 72, three-position four-way hydraulic control Reversing valve; 721, first oil output port; 722, second oil output port; 8, two-stage electromagnetic overflow valve; 81, two-position two-way electromagnetic overflow reversing valve; 82, externally controlled internal and external double-leakage overflow valve; 91, servo motor; 92, oil pump; 93, electric melt motor; 94, pressure-type cartridge valve; 95, cooler; 96, cartridge valve; 97, pressure regulating valve; 98, two-position two-way electromagnetic reversing valve; 10, mold opening and closing oil return pipeline. DETAILED DESCRIPTION

[0023] The following is combined with Figure 1-2 This application is described in further detail.

[0024] The embodiment of the present application discloses a pre-plasticizing oil replenishment control oil circuit for an electric melt adhesive structure of a PET product.

[0025] Reference Figure 1 A pre-plasticizing oil replenishment control oil circuit for an electric melt adhesive structure of a PET product, comprising an injection cylinder 1, a seat moving cylinder 2, an oil tank 3, an oil inlet pipeline 4 and an oil return pipeline 5 connected to the oil tank 3, a seat three-position four-way electromagnetic reversing valve 6 and a three-position four-way reversing valve group, an electric melt adhesive motor 93 for driving the screw to rotate, an oil pump 92 and a servo motor 91 are arranged on the oil inlet pipeline 4, and the oil in the oil tank 3 is pumped into the oil inlet pipeline 4 through the oil pump 92 and the servo motor 91.

[0026] The oil inlet pipeline 4 is first connected to the oil return pipeline 5 through a branch after the servo motor 91 through a relief valve, wherein the overflow valve adopts a two-stage electromagnetic overflow valve 8, and the two-stage electromagnetic overflow valve 8 includes a two-position two-way electromagnetic overflow reversing valve 81 and an externally controlled internal and external double leakage overflow valve 82. When the two-position two-way electromagnetic overflow reversing valve 81 is in the left position, the two oil ports are connected; when the two-position two-way electromagnetic overflow reversing valve 81 is in the right position, the two oil ports are disconnected, and the internal leakage port of the externally controlled internal and external double leakage overflow valve 82 is connected to the oil return pipeline 5, and the external leakage port of the externally controlled internal and external double leakage overflow valve 82 is connected to the oil return pipeline 5 and the spring port of the externally controlled internal and external double leakage overflow valve 82 through the two-position two-way electromagnetic overflow reversing valve 81.

[0027] The hydraulic oil in the oil return line 5 passes through the pressure-type cartridge valve 94 and the cooler 95 in sequence before entering the oil tank 3 .

[0028] The oil in the oil inlet pipeline 4 is respectively sent to the three-position four-way reversing valve group and the three-position four-way solenoid reversing valve 6 for the seat through two branches. The hydraulic oil is sent to the injection cylinder 1 through the three-position four-way reversing valve group, and is sent to the injection seat through the three-position four-way solenoid reversing valve 6 for the seat. The three positions of the three-position four-way reversing valve group correspond to the three processes of ejection, material storage and injection, and the three positions of the three-position four-way solenoid reversing valve 6 for the seat correspond to the moving direction of the injection seat and keeping it in place.

[0029] The three-position four-way reversing valve group is a three-position four-way electro-hydraulic reversing valve 7, which includes a three-position four-way solenoid reversing valve 71 and a three-position four-way hydraulically controlled reversing valve 72. The three-position four-way hydraulically controlled reversing valve 72 is provided with an oil inlet, an oil return port, a first oil output port 721 and a second oil output port 722. When the three-position four-way hydraulically controlled reversing valve 72 is in the middle position, only the first oil output port 721 is connected to the oil return port. When the three-position four-way hydraulically controlled reversing valve 72 is in the left position, the first oil output port 721 is connected to the oil return port, and the second oil output port 722 is connected to the oil inlet. When the three-position four-way hydraulically controlled reversing valve 72 is in the right position, the second oil output port 722 is connected to the oil return port, and the first oil output port 721 is connected to the oil inlet. The three-position four-way solenoid reversing valve 71 is provided with a control oil inlet 711, a control oil return port 712, a first control oil outlet 713 and a second control oil outlet 714. When the three-position four-way solenoid reversing valve 71 is in the middle position, the first control oil outlet 713 and the second control oil outlet 714 are both connected to the oil return port. When the three-position four-way solenoid reversing valve 71 is in the left position, the first control oil outlet 713 is connected to the oil return port, and the second control oil outlet 714 is connected to the oil inlet port. When the three-position four-way solenoid reversing valve 71 is in the right position, the second control oil outlet 714 is connected to the oil return port, and the first control oil outlet 713 is connected to the oil inlet port. The first control oil outlet 713 and the second control oil outlet 714 are connected to the left and right hydraulic control ports of the three-position four-way hydraulically controlled reversing valve 72 respectively. The oil inlet pipeline 4 and the oil return pipeline 5 are connected to the oil inlet and the oil return port of the three-position four-way hydraulically controlled reversing valve 72 respectively. The second output oil port 722 is connected to the rod chamber of the injection cylinder 1, and the first output oil port 721 is connected to the rodless chamber of the injection cylinder 1. When the piston rod of the injection cylinder 1 extends, the screw retreats.

[0030] Among them, the oil circuit between the second output oil port 722 and the injection cylinder 1 branches off and is connected to the return oil pipeline 5 after passing through a valve group composed of a cartridge valve 96, a pressure regulating valve 97 and a two-position two-way solenoid reversing valve 98. The oil inlet circuit of the cartridge valve 96 is divided into two control branches, which are respectively connected to the hydraulic control end of the cartridge valve 96 and an oil port of the two-position two-way solenoid reversing valve 98, and a non-adjustable flow valve is provided. The other oil port of the two-position two-way solenoid reversing valve 98 is connected to the return oil pipeline 5 after passing through the pressure regulating valve 97, and the left position of the two-position two-way solenoid reversing valve 98 is directly connected, while the right position is provided with a one-way valve structure and flows into the cartridge valve 96 and the second output oil port 722 in a one-way manner.

[0031] The seat-use three-position four-way solenoid reversing valve 6 is provided with four oil ports and are respectively connected to the oil inlet pipeline 4, the oil return pipeline 5, the rod chamber and the rodless chamber of the seat shifting cylinder 2. When the seat-use three-position four-way solenoid reversing valve 6 is in the middle position, the four oil ports of the seat-use three-position four-way solenoid reversing valve 6 are not connected. When the seat-use three-position four-way solenoid reversing valve 6 is in the left position, the oil inlet pipeline 4 is connected to the rodless chamber of the seat shifting cylinder 2, and the oil return pipeline 5 is connected to the rod chamber of the seat shifting cylinder 2. When the four-way solenoid reversing valve 6 is in the right position, the oil inlet pipeline 4 is connected to the rod chamber of the seat shifting cylinder 2, and the oil return pipeline 5 is connected to the rodless chamber of the seat shifting cylinder 2. A hydraulically controlled one-way valve 61 is arranged on the oil circuit between the three-position four-way solenoid reversing valve 6 and the rod chamber of the seat shifting cylinder 2. The hydraulically controlled one-way valve 61 controls the one-way flow of oil into the seat shifting cylinder 2. The hydraulically controlled end of the hydraulically controlled one-way valve 61 is connected to the rodless chamber of the seat shifting cylinder 2, and the seat shifting cylinder 2 pulls the injection seat to abut the nozzle.

[0032] At the same time, the return oil circuit of the oil circuit for opening and closing the mold of the injection molding machine is set as the return oil circuit 10 for opening and closing the mold. The return oil circuit 10 for opening and closing the mold is connected to the return oil pipeline 5. The position of connecting to the return oil pipeline 5 is between the three-position four-way electro-hydraulic reversing valve 7 and the pressure-type cartridge valve 94, so that the opening and closing of the mold and the storage of materials can be realized at the same time. The return oil for opening and closing the mold is the oil replenishment of the rodless chamber of the injection cylinder 1.

[0033] The implementation principle of the pre-plasticizing oil replenishment control oil circuit for the electric melt adhesive structure of the PET product in the embodiment of the present application is as follows: when the injection molding machine performs material storage without adding an additional power unit, due to the electric melt adhesive motor 93, there is no additional return oil to replenish the barless chamber of the injection cylinder 1. At this time, the oil pump 92 outputs, and due to the use of a two-stage electromagnetic overflow valve 8, the pressure is adjusted to 5-10bar during material storage, and the motor overflows. Since a pressure-type cartridge valve 94 is installed in front of the cooler 95 for the return oil of the motor, the valve core opening pressure is about 1bar. At this time, the return oil can be opened before overcoming the spring pressure of the pressure-type cartridge valve 94. First, directly enter the leverless chamber of the injection cylinder 1 through the three-position four-way electro-hydraulic reversing valve 7 to replenish oil and prevent vacuum from being pulled when the cylinder moves. In addition, when storing materials, the injection table is pushed to the bottom. When a hydraulic self-locking nozzle is not added, glue leakage will usually occur. This oil circuit is superimposed with a hydraulically controlled one-way valve 61 under the three-position four-way electromagnetic reversing valve 71 for seat shifting to prevent leakage. In addition, since the oil pump 92 has a low pressure of 5-10 bar, a certain low pressure can be established to enable the seat shifting cylinder 2 to have a forward force. In addition, if the mold is opened after cooling, the return oil of the opening and closing mold can be used to replenish the injection cylinder 1. The injection return oil and the opening and closing mold return oil are combined to realize the synchronization of mold opening and closing and material storage.

[0034] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A pre-plasticizing oil supply control oil circuit for PET product electromelt adhesive structure, characterized by: The invention comprises an injection cylinder (1), an oil tank (3), an oil inlet pipeline (4) and an oil return pipeline (5) connected to the oil tank (3), and a three-position four-way reversing valve group. The oil inlet pipeline (4) is provided with an oil pump (92) and a servo motor (91) for pumping oil in the oil tank (3) into the oil inlet pipeline (4). An overflow valve is provided between the oil inlet pipeline (4) and the oil return pipeline (5) and the two pipelines are connected through the overflow valve. A pressure-type cartridge valve (94) is provided on the oil return pipeline (5). The pressure-type cartridge valve (94) is located between the overflow valve and the oil tank (3). The three-position four-way reversing valve group comprises a three-position four-way reversing valve. The three-position four-way reversing valve is provided with an oil inlet port, an oil return port, a first oil output port (721) and a second oil output port (722). When the three-position four-way reversing valve is in a middle position, the first oil output port (721) is in a middle position. The oil outlet (721) is connected to the oil return port. When the three-position four-way reversing valve is in the left position, the first oil outlet (721) is connected to the oil return port, and the second oil outlet (722) is connected to the oil inlet. When the three-position four-way reversing valve is in the right position, the corresponding connection is opposite to that in the left position. The oil inlet pipeline (4) and the oil return pipeline (5) are respectively connected to the oil inlet and the oil return port of the three-position four-way reversing valve. The second oil outlet (722) is connected to the rod chamber of the injection cylinder (1), and the oil circuit between the second oil outlet (722) and the injection cylinder (1) is connected to the oil return pipeline (5) and is provided with a cartridge valve (96). The first oil outlet (721) is connected to the rodless chamber of the injection cylinder (1). When the piston rod of the injection cylinder (1) extends, the screw moves backward.

2. The pre-plasticizing oil supply control circuit for the electromelt adhesive structure of PET products according to claim 1, characterized in that: The three-position four-way reversing valve group is a three-position four-way electro-hydraulic reversing valve (7), the three-position four-way electro-hydraulic reversing valve (7) comprising a three-position four-way solenoid reversing valve (71) and a three-position four-way hydraulically controlled reversing valve (72), the three-position four-way hydraulically controlled reversing valve (72) being provided with an oil inlet, an oil return port, a first oil output port (721) and a second oil output port (722), when the three-position four-way hydraulically controlled reversing valve (72) is in a middle position, the first oil output port (721) is in communication with the oil return port, when the three-position four-way hydraulically controlled reversing valve (72) is in a left position, the first oil output port (721) is in communication with the oil return port, and the second oil output port (722) is in communication with the oil inlet, when the three-position four-way hydraulically controlled reversing valve (72) is in a right position, the corresponding communication is opposite to that when it is in a left position, and the three-position four-way solenoid reversing valve (72) is in communication with the oil inlet. (71) is provided with a control oil inlet (711), a control oil return port (712), a first control oil outlet (713) and a second control oil outlet (714). When the three-position four-way solenoid reversing valve (71) is in the middle position, the first control oil outlet (713) and the second control oil outlet (714) are both connected to the oil return port. When the three-position four-way solenoid reversing valve (71) is in the left position, the first control oil outlet (713) is connected to the oil return port, and the second control oil outlet (714) is connected to the oil inlet. When the three-position four-way solenoid reversing valve (71) is in the right position, the corresponding connections are opposite to those when it is in the left position. The first control oil outlet (713) and the second control oil outlet (714) are respectively connected to the left and right hydraulic control ports of the three-position four-way hydraulic control reversing valve (72).

3. A pre-plasticizing oil supply control oil circuit for an electric melt adhesive structure of a PET product according to claim 1 or 2, characterized in that: It also includes a seat oil cylinder (2) and a three-position four-way electromagnetic reversing valve (6) for the seat. The three-position four-way electromagnetic reversing valve (6) for the seat is provided with four oil ports and respectively connected to the oil inlet pipeline (4), the oil return pipeline (5), the rod chamber and the rodless chamber of the seat oil cylinder (2). When the three-position four-way electromagnetic reversing valve (6) for the seat is in the middle position, the four oil ports of the three-position four-way electromagnetic reversing valve (6) for the seat are not connected. When the three-position four-way electromagnetic reversing valve (6) for the seat is in the left position, the oil inlet pipeline (4) is connected to the seat oil cylinder. (2), the return oil pipeline (5) is connected to the rod-bearing chamber of the seat-moving oil cylinder (2), and when the three-position four-way electromagnetic reversing valve (6) for the seat is in the right position, the oil port corresponding to the left position is swapped, and a hydraulically controlled one-way valve (61) is arranged between the three-position four-way electromagnetic reversing valve (6) for the seat and the rod-bearing chamber of the seat-moving oil cylinder (2) to control the one-way flow of oil into the seat-moving oil cylinder (2), and the hydraulically controlled end of the hydraulically controlled one-way valve (61) is connected to the rod-bearing chamber of the seat-moving oil cylinder (2), and the seat-moving oil cylinder (2) pulls the injection seat to abut the nozzle.

4. The pre-plasticizing oil supply control oil circuit for the electromelt adhesive structure of PET products according to claim 1, characterized in that: The overflow valve is a two-stage electromagnetic overflow valve (8).

5. The pre-plasticizing oil supply control oil circuit for the electric melt adhesive structure of PET products according to claim 1, characterized in that: The oil return pipeline (5) is provided with a cooler (95) between the pressure-type cartridge valve (94) and the oil tank (3).

6. The pre-plasticizing oil supply control oil circuit for the electromelt adhesive structure of PET products according to claim 1, characterized in that: It also includes a pressure regulating valve (97) and a two-position two-way electromagnetic reversing valve (98). The oil inlet circuit of the cartridge valve (96) is divided into two control branches, which are respectively connected to the hydraulic control end of the cartridge valve (96) and an oil port of the two-position two-way electromagnetic reversing valve (98). The other oil port of the two-position two-way electromagnetic reversing valve (98) is connected to the return oil pipeline (5) after passing through the pressure regulating valve (97). The left position of the two-position two-way electromagnetic reversing valve (98) is directly connected, while the right position is provided with a one-way valve structure and flows into the control branch in one direction.

7. The pre-plasticizing oil supply control circuit for the electromelt adhesive structure of PET products according to claim 1, characterized in that: The return oil of the injection molding machine when opening and closing the mold is connected to the return oil pipeline (5).

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