Stable glue supply system and method for glue dispensing valve

Abstract

The invention discloses a stable glue supply system and method for a dispensing valve. The system comprises a first PLC, a second PLC, a first PLC input, a second PLC input, a glue barrel, a glue supply pump, a galvanometer, an overflow valve, a belt feedback pressure gauge, a fixed differential pressure reducing valve, an adjustable throttling valve, the dispensing valve, a dispensing valve glue outlet, a two-position four-way electromagnetic valve, a glue valve fluid cavity, a piston, a valve rod and a valve nozzle. The output pressure of the glue supply pump is represented as PO, the set pressure of the overflow valve is represented as P00, the pressure detected by the belt feedback pressure gauge and the input pressure of the fixed differential pressure reducing valve are represented as P1, the pressure of the fixed differential pressure reducing valve after the P1 is reduced is represented as Pm, and the pressure of the rear end of the adjustable throttle valve is represented as Pn, the stable glue supply system and method for the glue dispensing valve are suitable for the glue dispensing industry, and the pain point of unstable glue supply flow in the glue dispensing industry is solved; the dispensing flow stability is good, the structure is simple, PLC logic is simple, and debugging is easy.

Description

Technical Field

[0001] The invention belongs to the technical field of glue dispensing valves, and in particular relates to a system and method for stably supplying glue to a glue dispensing valve. Background Art

[0002] In current industrial production, dispensing technology is widely used in various fields, such as electronics, automobiles, and medical treatment. As the core component of dispensing equipment, the glue supply stability of the glue valve has an important impact on the dispensing quality, because the glue supply pressure will directly affect the flow rate of the glue. When the flow rate changes during the operation of the valve, the dispensing effect will be greatly affected. Using a pump to supply glue to the dispensing valve is a common way of supplying glue. Since there is a certain distance between the pump and the valve, and the pressure of the glue output by the pump is often unstable, the existing solutions are:

[0003] Solution 1: Add a voltage stabilizer between the pump and the dispensing valve, which is often called a constant-value pressure reducing valve ( Figure 1 ), this method can effectively reduce the glue supply pressure of the dispensing valve, but when the glue supply pressure P1 of the dispensing valve is reduced, the glue flow rate of the dispensing valve will be reduced, and the pressure reducing valve cannot provide the flow rate required by the dispensing valve, which will cause unstable dispensing;

[0004] Solution 2: Figure 1 The pressure reducing valve in the dispensing system is replaced with an electric proportional flow valve. Although it can control a stable flow, the proportional valve has requirements for response speed and is often suitable for low-viscosity liquids. It is often not effective for medium- and high-viscosity liquids. Therefore, this solution is less useful in the dispensing industry.

[0005] Solution 3: Figure 1 The middle voltage stabilizer is replaced by a metering pump. The metering pump with stable flow and no pulsation is a plunger pump, so the plunger pump is often used as the glue supply pump of the dispensing valve (of course, the glue of the metering pump comes from the previous glue supply pump). However, since the metering pump is like a syringe for injection, there is a sequence of suction first and then discharge, and the glue supply flow of the dispensing valve is controlled by controlling the change in volume in the plunger. The disadvantage of this solution is that the dispensing valve cannot discharge glue continuously for a long time, and the cost of the plunger pump is high, so it is only used in fewer working conditions.

[0006] There are still many application occasions where the problem of unstable glue supply flow rate of glue dispensing valve has not been solved. For this reason, the present invention provides a system and method for stable glue supply to glue dispensing valve. Summary of the invention

[0007] The present invention aims to provide a system and method for stably supplying glue to a glue dispensing valve, so as to solve the technical problems raised in the background technology.

[0008] To achieve the above-mentioned purpose, the specific technical scheme of the present invention is as follows: a stable glue supply system for a dispensing valve, including a first PLC control, a second PLC control, a first PLC input, a second PLC input, a glue barrel, a glue supply pump, a current meter, an overflow valve, a pressure gauge with feedback, a differential pressure reducing valve, an adjustable flow valve, a dispensing valve, a dispensing valve glue outlet, a two-position four-way solenoid valve, a glue valve fluid chamber, a piston, a valve stem and a valve nozzle.

[0009] Preferably, the output pressure of the glue supply pump is represented as PO, the pressure set by the overflow valve is represented as P00, the pressure detected by the feedback pressure gauge and the input pressure of the differential pressure reducing valve are both represented by P1, the pressure after the differential pressure reducing valve reduces the pressure of P1 is represented as Pm, and the pressure at the rear end of the adjustable flow valve is represented as Pn.

[0010] Preferably, when the valve stem contacts the valve nozzle, the dispensing valve is closed and no glue is discharged from the dispensing valve outlet;

[0011] When the valve stem is separated from the valve nozzle, the dispensing valve is opened, and the dispensing valve dispensing glue to the product through the dispensing outlet.

[0012] Preferably, the valve stem and the valve nozzle form a throttle valve for glue, the pressure at the front end of the switch is P2, the pressure at the rear end of the switch is P3, the atmospheric pressure is P4, and the pressure of glue in the atmosphere is 0, that is, P4=0.

[0013] A method for stably supplying glue to a dispensing valve, comprising the following steps:

[0014] Step 1: First, the state of dispensing is that the first PLC controls the power off, the two-position four-way solenoid valve is in the spring position, the dispensing valve is closed, and the second PLC controls the glue supply pump to start working and supplying glue;

[0015] Step 2: When the first PLC input has a signal, that is, when fluid passes through the galvanometer, it means that the overflow valve begins to overflow, and glue begins to flow through the differential pressure reducing valve and the adjustable flow valve. The first PLC controls power on, so that the dispensing valve is in the open state. After discharging the front glue for a period of time, the first PLC controls power off, and the dispensing valve is in the closed state; when the first PLC input has a signal, the second PLC controls the glue supply pump to stop working;

[0016] Step 3: The second PLC input feeds back the pressure P1 detected by the feedback pressure gauge to the PLC, and the PLC compares P1 with the manually set Ps;

[0017] Step 4: When the PLC determines that P1>1.1Ps, the first PLC controls the two-position four-way solenoid valve to be energized at the corresponding time according to the setting of the production programmer, that is, the dispensing valve opens the glue to dispense the product. At the same time, the second PLC controls the glue supply pump to supply glue and controls the pump to work at the set flow rate Q; until the product dispensing is completed, then the first PLC controls to be closed, the second PLC controls to be closed, and step 3 is repeated;

[0018] Step 5: When the PLC determines that P1 is less than 1.1Ps, the second PLC controls the glue supply pump to supply glue. When the PLC determines that P1 is greater than 1.1Ps, the second PLC controls the glue supply pump to stop working and proceed to step 3. When the PLC determines that P1 is less than 1.1Ps and the first PLC input has a signal, it means that the pressure setting P00 of the overflow valve is too low and the overflow pressure needs to be increased.

[0019] Step 6: When the product dispensing is completed, the first PLC control and the second PLC control can be turned off. Before the next product arrives, the equipment program enters step 3;

[0020] Step 7: When the equipment is working, the PLC will perform timed glue discharge to prevent the glue from solidifying according to whether it is in working state. The timed glue discharge is when the first PLC control and the second PLC control are turned on at the same time.

[0021] Preferably, the specific method of setting the parameters Ps and Q is as follows: the general flow formula for throttling is Q=Kq*A*ΔP^m, where m=0.5 for thin-walled holes and m=1 for elongated holes, and Kq is affected by factors such as density or viscosity, pipe shape and length, and is a constant under this working condition;

[0022] The general flow formula for pipeline circulation is Q = μ*A*(2*ΔP / ρ)^0.5, where the flow coefficient μ, area A, and fluid density ρ are all constants.

[0023] Preferably, the flow rate of the adjustable flow valve is Q1, m = 0.5, and the formula is: Q1 = Kq1*A1*ΔP^0.5 = K1*A1, where K1 = Kq1*C^0.5 is a constant;

[0024] The flow rate from the end of the adjustable flow valve to the front end of the switch composed of the valve stem and the valve nozzle is Q2, and the selection formula is: Q2 = μ2*A2*(2*(Pn-P2) / ρ)^0.5 = K2*(Pn-P2)^0.5, where K2 = μ2*A2*(2 / ρ)^0.5 is a constant;

[0025] The flow rate of the switch composed of the valve stem and the valve nozzle is Q3, A3 is unchanged, close to the thin-walled hole m = 0.5, Q3 = Kq3 * A3 * ΔP^m = K3 * (P2-P3)^0.5, where K3 = Kq3 * A3 is a constant,

[0026] The flow rate from the switch composed of the valve stem and the valve nozzle to the dispensing valve outlet is Q4, and the formula is: Q4 = μ4*A4*(2*P3 / ρ)^0.5 = K4*P3^0.5, where K4 = μ4*A4*(2 / ρ)^0.5 is a constant;

[0027] Refining the above four flows, that is, the formula:

[0028] Q1=K1*A1

[0029] Q2=K2*(Pn-P2)^0.5

[0030] Q3=K3*(P2-P3)^0.5

[0031] Q4=K4*P3^0.5

[0032] Among them, Q4 is the flow rate of the final dispensing valve outlet.

[0033] There is also the flow continuity theorem: Q1 = Q2 = Q3 = Q4 = K1*A1, K1 is a constant, A1 is controlled by the throttling area of ​​the adjustable flow valve. The size of A1 can be adjusted according to demand to obtain the desired steady-state flow K1*A1, that is, the flow of Q4;

[0034] In the stable dispensing process, A1 is constant, that is, Q4 is constant. The value of Q4 can be calculated through simulation or on-site glue measurement. There is also a differential pressure reducing valve, and we can get: Pm-Pn=C. Combining the expressions of Q1, Q2, Q3 and Q4, we can get the conclusion.

[0035] Preferably, where Pm = (Q4 / K4)^2*((K4 / K2)^2+(K4 / K3)^2+1)+C, is a constant,

[0036] P4=0,

[0037] P3=(Q4 / K4)^2, which is a constant

[0038] P2=(Q4 / K4)^2*((K4 / K3)^2+1), which is a constant

[0039] Pn=(Q4 / K4)^2*((K4 / K2)^2+(K4 / K3)^2+1), which is a constant.

[0040] Preferably, when the dispensing valve is closed: P0>P00=P1=Pm=Pn=P2>P3=P4=0, since the pipelines of Pm-Pn-P2-P3 are rigidly connected, the fluid is incompressible and continuous, then at the moment of opening the valve, the pressure at each point will suddenly change to the steady-state pressure, and the system flow change at this time can be judged according to Q1; since Q1=Kq1*A1*ΔP^(1 / 2), where Kq1 is a constant, A1 is a constant, ΔP=Pm-Pn is an instantaneous change, from 0 to C, then at this moment, Q1 changes from 0 to Kq1*A1*C^0.5=K1*A1=Q4;

[0041] That is to say, the moment after the valve is opened, the flow rate Q4 at the glue outlet of the dispensing valve changes from 0 to the desired steady-state flow rate K1*A1. That is to say, the moment after the valve is opened, the flow rate Q4 at the glue outlet of the dispensing valve is uneven, and changes from 0 to the desired steady-state flow rate K1*A1.

[0042] The present invention provides a stable glue supply system and method for a glue dispensing valve, which has the following advantages: it is suitable for the glue dispensing industry and solves the pain point of unstable glue supply flow in the glue dispensing industry; the glue dispensing flow has good stability, simple structure, simple PLC logic, and simple debugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 It is a principle diagram of a fixed value pressure reducing valve in the prior art of the present invention;

[0045] Figure 2 This is a schematic diagram of the glue supply principle of the present invention;

[0046] Figure 3 This is a schematic diagram of the glue valve of the present invention;

[0047] Figure 4 It is a schematic diagram of the glue valve of the present invention.

[0048] Explanation of the marks in the figure: 1. First PLC control; 2. Second PLC control; 3. First PLC input; 4. Second PLC input; 11. Glue barrel; 12. Glue supply pump; 13. Ammeter; 14. Overflow valve; 15. Pressure gauge with feedback; 21. Differential pressure reducing valve; 22. Adjustable flow valve; 31. Glue dispensing valve; 32. Glue dispensing valve outlet; 33. Two-position four-way solenoid valve; 311. Glue valve fluid chamber; 312. Piston; 313. Valve stem; 314. Valve nozzle. DETAILED DESCRIPTION

[0049] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0050] In the description of the embodiments of the present invention, it should be understood that the terms "length", "vertical", "horizontal", "top", "bottom", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0052] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0053] The disclosure below provides many different embodiments or examples to implement different structures of the embodiments of the present invention. In order to simplify the disclosure of the embodiments of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the embodiments of the present invention. In addition, the embodiments of the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0054] In order to better understand the purpose, structure and function of the present invention, the following further describes in detail a system and method for stably supplying glue to a dispensing valve of the present invention in conjunction with the accompanying drawings.

[0055] like Figure 2-4 As shown, a stable glue supply system for a glue dispensing valve of the present invention comprises a first PLC control 1, a second PLC control 2, a first PLC input 3, a second PLC input 4, a glue barrel 11, a glue supply pump 12, a galvanometer 13, an overflow valve 14, a pressure gauge with feedback 15, a differential pressure reducing valve 21, an adjustable flow valve 22, a glue dispensing valve 31, a glue dispensing valve outlet 32, a two-position four-way solenoid valve 33, a glue valve fluid chamber 311, a piston 312, a valve stem 313 and a valve nozzle 314. The output pressure of the glue supply pump 12 is represented as PO, the pressure set by the overflow valve 14 is represented as P00, the pressure detected by the pressure gauge with feedback 15 and the input pressure of the differential pressure reducing valve 21 are both represented by P1, the pressure after the differential pressure reducing valve 21 reduces the pressure by P1 is represented as Pm, and the pressure at the rear end of the adjustable flow valve 22 is represented as Pn. When the valve stem 313 contacts the valve nozzle 314, the dispensing valve is closed and the dispensing valve outlet 32 ​​does not dispense glue; when the valve stem 313 separates from the valve nozzle 314, the dispensing valve is opened and the dispensing valve outlet 32 ​​dispenses glue to the product. The valve stem 313 and the valve nozzle 314 form a throttle valve for glue, the pressure at the front end of the switch is P2, the pressure at the rear end of the switch is P3, the atmospheric pressure is P4, and the pressure of glue in the atmosphere is 0, that is, P4=0.

[0056] The present invention also discloses a method for stably supplying glue to a glue dispensing valve, which specifically comprises the following steps:

[0057] Step 1: First, the state of glue dispensing is that the first PLC control 1 is powered off, the two-position four-way solenoid valve 33 is in the spring position, the glue dispensing valve 31 is closed, and the second PLC control 2 controls the glue supply pump 12 to start working and supplying glue;

[0058] Step 2: When the first PLC input 3 has a signal, that is, when fluid passes through the galvanometer 13, it means that the overflow valve 14 begins to overflow, and glue begins to flow through the differential pressure reducing valve 21 and the adjustable flow valve 22. The first PLC control 1 is powered on, so that the dispensing valve 31 is in Figure 4The purpose of this is to discharge the front glue in the entire pipeline. The front glue often has more bubbles, etc. The front glue is not discharged as waste glue. If the glue is dispensed on the product, it will affect the quality of the dispensing. After discharging the front glue for a period of time, the first PLC control 1 is powered off, and the dispensing valve 31 is in Figure 3 When the first PLC input 3 has a signal, the second PLC controls 2 to stop the glue supply pump 12, which can save energy and reduce the friction between the glue and the pipeline loop;

[0059] Step 3: The second PLC input 4 feeds back the pressure P1 detected by the feedback pressure gauge 15 to the PLC, and the PLC compares P1 with the manually set Ps;

[0060] Step 4: When the PLC determines that P1>1.1Ps, the first PLC controls 1 to energize the two-position four-way solenoid valve 33 at the corresponding time according to the setting of the production programmer, that is, the dispensing valve 31 opens the glue to dispense the product. At the same time, the second PLC controls 2 to control the glue supply pump 12 to work and supply glue, and controls the pump to work at the set flow rate Q; until the product dispensing is completed, then the first PLC controls 1 to close, the second PLC controls 2 to close, and repeat step 3;

[0061] Step 5: When the PLC determines that P1 is less than 1.1Ps, the second PLC controls 2 to control the glue supply pump 12 to work and supply glue. When the PLC determines that P1 is greater than 1.1Ps, the second PLC controls 2 to control the glue supply pump 12 to stop working, and proceeds to step 3. When the PLC determines that P1 is less than 1.1Ps, and the first PLC input 3 has a signal, it means that the pressure setting P00 of the overflow valve 14 is too low, and the overflow pressure needs to be increased.

[0062] Step 6: When the product dispensing is completed, the first PLC control 1 and the second PLC control 2 are closed, and before the next product arrives, the equipment program enters step 3;

[0063] Step 7: When the equipment is working, the PLC performs timed glue discharge to prevent the glue from solidifying according to whether it is in working state. The timed glue discharge is when the first PLC control 1 and the second PLC control 2 are turned on simultaneously.

[0064] The specific method of setting the parameters Ps and Q is as follows: The general flow formula for throttling is Q = Kq*A*ΔP^m, where m = 0.5 for thin-walled holes and m = 1 for slender holes. Kq is affected by factors such as density or viscosity, pipe shape and length, and is a constant under this working condition.

[0065] The general flow formula for pipeline circulation is Q = μ*A*(2*ΔP / ρ)^0.5, where the flow coefficient μ, area A, and fluid density ρ are all constants.

[0066] The flow rate of the adjustable flow valve 22 is Q1, m = 0.5, and the formula used is: Q1 = Kq1*A1*ΔP^0.5 = K1*A1, where K1 = Kq1*C^0.5 is a constant;

[0067] The flow rate from the end of the adjustable flow valve 22 to the front end of the switch composed of the valve stem 313 and the valve nozzle 314 is Q2, and the formula used is: Q2 = μ2*A2*(2*(Pn-P2) / ρ)^0.5 = K2*(Pn-P2)^0.5, where K2 = μ2*A2*(2 / ρ)^0.5 is a constant;

[0068] The flow rate of the switch composed of the valve stem 313 and the valve nozzle 314 is Q3, A3 is constant, close to the thin-walled hole m=0.5, Q3=Kq3*A3*ΔP^m=K3*(P2-P3)^0.5, where K3=Kq3*A3 is a constant,

[0069] The flow rate from the switch composed of the valve stem 313 and the valve nozzle 314 to the dispensing valve outlet 32 ​​is Q4, and the formula used is: Q4 = μ4*A4*(2*P3 / ρ)^0.5 = K4*P3^0.5, where K4 = μ4*A4*(2 / ρ)^0.5 is a constant;

[0070] Refining the above four flows, that is, the formula:

[0071] Q1=K1*A1

[0072] Q2=K2*(Pn-P2)^0.5

[0073] Q3=K3*(P2-P3)^0.5

[0074] Q4=K4*P3^0.5

[0075] Q4 is the flow rate of the final dispensing valve outlet 32.

[0076] There is also the flow continuity theorem: Q1 = Q2 = Q3 = Q4 = K1*A1, K1 is a constant, A1 is controlled by the throttling area of ​​the adjustable flow valve. The size of A1 can be adjusted according to demand to obtain the desired steady-state flow K1*A1, that is, the flow of Q4;

[0077] In the stable dispensing process, A1 is constant, that is, Q4 is constant. The value of Q4 can be calculated through simulation or on-site glue measurement. There is also a differential pressure reducing valve, and we can get: Pm-Pn=C. Combining the expressions of Q1, Q2, Q3 and Q4, we can get the conclusion.

[0078] Where Pm = (Q4 / K4)^2*((K4 / K2)^2+(K4 / K3)^2+1)+C, is a constant,

[0079] P4=0,

[0080] P3=(Q4 / K4)^2, which is a constant

[0081] P2=(Q4 / K4)^2*((K4 / K3)^2+1), which is a constant

[0082] Pn=(Q4 / K4)^2*((K4 / K2)^2+(K4 / K3)^2+1), which is a constant.

[0083] When the dispensing valve (31) is closed: P0>P00=P1=Pm=Pn=P2>P3=P4=0, since the pipelines of Pm-Pn-P2-P3 are rigidly connected, the fluid is incompressible and continuous, then at the moment of opening the valve, the pressure at each point will suddenly change to the steady-state pressure, and the system flow change at this time can be judged according to Q1; since Q1=Kq1*A1*ΔP^(1 / 2), where Kq1 is a constant, A1 is a constant, ΔP=Pm-Pn is an instantaneous change, from 0 to C, then at this moment, Q1 changes from 0 to Kq1*A1*C^0.5=K1*A1=Q4;

[0084] That is to say, the moment after the valve is opened, the flow rate Q4 of the glue outlet 32 ​​of the glue dispensing valve changes from 0 to the desired steady-state flow rate K1*A1. That is to say, the moment after the valve is opened, the flow rate Q4 of the glue outlet 32 ​​of the glue dispensing valve is uneven, and changes from 0 to the desired steady-state flow rate K1*A1.

[0085] Finally, how to set the parameters Ps and Q:

[0086] From the transient and steady-state analysis above, we can know that the steady-state parameter setting determines the dispensing flow rate. Q4 = K1*A1, K1 is constant, which means that only the parameters of A1 determine the size of Q4, and A1 corresponds to Q4 one by one.

[0087] In actual production, Q4 is obtained by continuously adjusting A1 on the adjustable flow valve 22, or the desired Q4 is simulated in advance by software to obtain the size of A1.

[0088] The general setting Q=1.2*Q4 is to reduce the overflow and thus reduce the friction between the glue and the pipe.

[0089] The general setting is Ps=Pm=(Q4 / K4)^2*((K4 / K2)^2+(K4 / K3)^2+1)+C.

[0090] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A stable glue supply system for a glue dispensing valve, characterized by: The invention comprises a first PLC control (1), a second PLC control (2), a first PLC input (3), a second PLC input (4), a glue barrel (11), a glue supply pump (12), a galvanometer (13), a relief valve (14), a pressure gauge with feedback (15), a differential pressure reducing valve (21), an adjustable flow valve (22), a glue dispensing valve (31), a glue dispensing valve glue outlet (32), a two-position four-way solenoid valve (33), a glue valve fluid chamber (311), a piston (312), a valve stem (313) and a valve nozzle (314).

2. A stable glue supply system for a glue dispensing valve according to claim 1, characterized in that: The output pressure of the glue supply pump (12) is represented by PO, the pressure set by the overflow valve (14) is represented by P00, the pressure detected by the feedback pressure gauge (15) and the input pressure of the differential pressure reducing valve (21) are both represented by P1, the pressure after the differential pressure reducing valve (21) reduces the pressure of P1 is represented by Pm, and the pressure at the rear end of the adjustable flow valve (22) is represented by Pn.

3. A stable glue supply system for a glue dispensing valve according to claim 1, characterized in that: When the valve stem (313) contacts the valve nozzle (314), the dispensing valve is closed and the dispensing valve outlet (32) does not dispense glue; When the valve stem (313) is separated from the valve nozzle (314), the dispensing valve is opened, and the dispensing valve outlet (32) dispenses glue to the product.

4. The stable glue supply system for glue dispensing valve according to claim 1, characterized in that: The valve stem (313) and the valve nozzle (314) form a throttle valve for glue. The pressure at the front end of the switch is P2, the pressure at the rear end of the switch is P3, the atmospheric pressure is P4, and the pressure of glue in the atmosphere is 0, that is, P4=0.

5. A method for stably supplying glue to a dispensing valve, characterized in that: The specific steps include: Step 1: First, the state of glue dispensing is that the first PLC control (1) is powered off, the two-position four-way solenoid valve (33) is in the spring position, the glue dispensing valve (31) is closed, and the second PLC control (2) controls the glue supply pump (12) to start working and supplying glue; Step 2: When the first PLC input (3) has a signal, that is, when fluid passes through the galvanometer (13), it means that the overflow valve (14) begins to overflow, and glue begins to flow through the differential pressure reducing valve (21) and the adjustable flow valve (22). The first PLC control (1) is powered on, so that the glue dispensing valve (31) is in an open state. After a period of time of discharging the front glue, the first PLC control (1) is powered off, and the glue dispensing valve (31) is in a closed state. When the first PLC input (3) has a signal, the second PLC control (2) stops the glue supply pump (12). Step 3: The second PLC input (4) feeds back the pressure P1 detected by the feedback pressure gauge (15) to the PLC, and the PLC compares P1 with the manually set Ps; Step 4: When the PLC determines that P1>1.1Ps, the first PLC control (1) controls the two-position four-way solenoid valve (33) to be energized at a corresponding time according to the setting of the production programmer, that is, the dispensing valve (31) opens the glue to dispense the product. At the same time, the second PLC control (2) controls the glue supply pump (12) to work and supply glue, and controls the pump to work at the set flow rate Q; until the product dispensing is completed, then the first PLC control (1) is closed, the second PLC control (2) is closed, and step 3 is repeated; Step 5: When the PLC determines that P1 is less than 1.1Ps, the second PLC control (2) controls the glue supply pump (12) to start supplying glue. When the PLC determines that P1 is greater than 1.1Ps, the second PLC control (2) controls the glue supply pump (12) to stop working and proceed to step 3. When the PLC determines that P1 is less than 1.1Ps and the first PLC input (3) has a signal, it means that the pressure setting P00 of the overflow valve (14) is too low and the overflow pressure needs to be increased. Step 6: When the product dispensing is completed, the first PLC control (1) and the second PLC control (2) are both closed, and before the next product arrives, the equipment program enters step 3; Step 7: When the equipment is working, the PLC performs timed glue discharge to prevent the glue from solidifying according to whether it is in working state. The timed glue discharge is when the first PLC control (1) and the second PLC control (2) are turned on simultaneously.

6. A method for stably supplying glue to a dispensing valve according to claim 5, characterized in that: The specific method of setting the parameters Ps and Q is as follows: The general flow formula for throttling is Q = Kq*A*ΔP^m, where m = 0.5 for thin-walled holes and m = 1 for slender holes. Kq is affected by factors such as density or viscosity, pipe shape and length, and is a constant under this working condition. The general flow formula for pipeline circulation is Q=μ*A*(2*ΔP / ρ)^0.5, where the flow coefficient μ, area A, and fluid density ρ are all constants.

7. A method for stably supplying glue to a dispensing valve according to claim 6, characterized in that: The flow rate of the adjustable flow valve (22) is Q1, m = 0.5, and the formula used is: Q1 = Kq1*A1*ΔP^0.5 = K1*A1, where K1 = Kq1*C^0.5 is a constant; The flow rate from the end of the adjustable flow valve (22) to the front end of the switch composed of the valve stem (313) and the valve nozzle (314) is Q2, and the formula used is: Q2 = μ2*A2*(2*(Pn-P2) / ρ)^0.5 = K2*(Pn-P2)^0.5, where K2 = μ2*A2*(2 / ρ)^0.5 is a constant; The flow rate of the switch composed of the valve stem (313) and the valve nozzle (314) is Q3, A3 is constant, close to the thin-walled hole m=0.5, Q3=Kq3*A3*ΔP^m=K3*(P2-P3)^0.5, where K3=Kq3*A3 is a constant. The flow rate from the switch composed of the valve stem (313) and the valve nozzle (314) to the dispensing valve outlet (32) is Q4, and the formula used is: Q4 = μ4*A4*(2*P3 / ρ)^0.5 = K4*P3^0.5, where K4 = μ4*A4*(2 / ρ)^0.5 is a constant; Refining the above four flows, that is, the formula: Q1=K1*A1 Q2=K2*(Pn-P2)^0.5 Q3=K3*(P2-P3)^0.5 Q4=K4*P3^0.5 Where Q4 is the flow rate of the final dispensing valve outlet (32). There is also the flow continuity theorem: Q1 = Q2 = Q3 = Q4 = K1*A1, K1 is a constant, A1 is controlled by the throttling area of ​​the adjustable flow valve. The size of A1 can be adjusted according to demand to obtain the desired steady-state flow K1*A1, that is, the flow of Q4; In the stable dispensing process, A1 is constant, that is, Q4 is constant. The value of Q4 can be calculated through simulation or on-site glue measurement. There is also a differential pressure reducing valve, and we can get: Pm-Pn=C. Combining the expressions of Q1, Q2, Q3 and Q4, we can get the conclusion.

8. A method for stably supplying glue to a dispensing valve according to claim 7, characterized in that: Where Pm = (Q4 / K4)^2*((K4 / K2)^2+(K4 / K3)^2+1)+C, is a constant, P4＝0， P3=(Q4 / K4)^2, which is a constant P2=(Q4 / K4)^2*((K4 / K3)^2+1), which is a constant Pn=(Q4 / K4)^2*((K4 / K2)^2+(K4 / K3)^2+1), which is a constant.

9. The method for stably supplying glue to a dispensing valve according to claim 7, characterized in that: When the dispensing valve (31) is closed: P0>P00=P1=Pm=Pn=P2>P3=P4=0, since the pipelines of Pm-Pn-P2-P3 are rigidly connected, the fluid is incompressible and continuous, then at the moment of opening the valve, the pressure at each point will suddenly change to the steady-state pressure, and the system flow change at this time can be judged according to Q1; since Q1=Kq1*A1*ΔP^(1 / 2), where Kq1 is a constant, A1 is a constant, ΔP=Pm-Pn is an instantaneous change, from 0 to C, then at this moment, Q1 changes from 0 to Kq1*A1*C^0.5=K1*A1=Q4; That is to say, the moment after the valve is opened, the flow rate Q4 of the glue outlet (32) of the glue dispensing valve changes from 0 to the desired steady-state flow rate K1*A1. That is to say, the moment after the valve is opened, the flow rate Q4 of the glue outlet (32) of the glue dispensing valve is uneven, and changes from 0 to the desired steady-state flow rate K1*A1.

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