阅读说明：本技术 一种金属切削加工冷却气体射流场的制冷参数调控方法 (Refrigeration parameter regulation and control method for metal cutting processing cooling gas jet flow field ) 是由 黄海鸿 刘帅帅 朱利斌 王英 刘志峰 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种金属切削加工冷却气体射流场的制冷参数调控方法,是应用于由气源、闸阀、增压泵、高压容器、热交换器、高压电磁阀、渐缩喷嘴、控制器以及温度传感器、压力传感器和输送管路、进气管路、出气管路所组成的调控系统中,通过控制器控制热交换器和增压泵改变高压容器内气体的温度、压强以改变渐缩喷嘴入口前端气体的温度、压强；在环境以及出气管路损耗等因素的影响下,结合建立的系统的流体热力学模型,通过控制器进行实际的渐缩喷嘴出口处的气体温度和射流场每秒流出气体的焓与理论的数值比较后调控,实现稳定准确地控制渐缩喷嘴出口处的气体温度和射流场每秒流出气体的焓。(The invention discloses a refrigeration parameter regulating method for a metal cutting processing cooling gas jet flow field, which is applied to a regulating system consisting of a gas source, a gate valve, a booster pump, a high-pressure container, a heat exchanger, a high-pressure electromagnetic valve, a convergent nozzle, a controller, a temperature sensor, a pressure sensor, a conveying pipeline, an air inlet pipeline and an air outlet pipeline, wherein the controller controls the heat exchanger and the booster pump to change the temperature and the pressure of the gas in the high-pressure container so as to change the temperature and the pressure of the gas at the front end of an inlet of the convergent nozzle; under the influence of factors such as environment and gas outlet pipeline loss, the fluid thermodynamic model of the established system is combined, the actual gas temperature at the outlet of the convergent nozzle and the enthalpy of gas flowing out of the jet flow field per second are compared with theoretical values through the controller and then regulated, and the stable and accurate control of the gas temperature at the outlet of the convergent nozzle and the enthalpy of gas flowing out of the jet flow field per second is realized.)

1. A refrigeration parameter regulation and control method for a metal cutting machining cooling gas jet flow field is applied to a regulation and control system consisting of a gas cylinder (1), a gate valve (2), a booster pump (3), a first temperature sensor (4), a first pressure sensor (5), a high-pressure container (6), a heat exchanger (7), a controller (8), a high-pressure electromagnetic valve (9), a second temperature sensor (10), a second pressure sensor (11) and a convergent nozzle (12), wherein the gas cylinder (1) is connected with the booster pump (3) through a conveying pipeline, and the conveying pipeline is provided with the gate valve (2); the booster pump (3) is connected with the high-pressure container (6) through an air inlet pipeline, a first temperature sensor (4) and a first pressure sensor (5) are arranged in the high-pressure container (6), and a heat exchanger (7) is arranged on the outer wall of the high-pressure container (6); the high-pressure container (6) is connected with the convergent nozzle (12) through an air outlet pipeline, a high-pressure electromagnetic valve (9) is arranged on the air outlet pipeline, and a second temperature sensor (10) and a second pressure sensor (11) are arranged at an inlet at the front end of the convergent nozzle (12); the method is characterized by comprising the following steps of:

step 1, according to the gas temperature T at the outlet of the convergent nozzle (12) required by metal cutting_jf,0Enthalpy of gas flowing out per second of jet field theoryCalculating the temperature demand T of the gas at the inlet of the front end of the convergent nozzle (12) by combining a gas thermodynamic model at the convergent nozzle (12)_nozzle,iAnd a pressure requirement value P_nozzle,i；

Step 2, opening the gate valve (2), and enabling gas to flow to the booster pump (3) through the delivery pipe from the gas cylinder (1);

step 3, the controller (8) sets the initial value T of the temperature of the gas in the high-pressure container (6)_gt,0Initial value of pressure P_gt,0Respectively the temperature requirement values T of the gas at the inlet of the front end of the convergent nozzle (12)_nozzle,0And a pressure requirement value P_nozzle,0Controlling the booster pump (3) to be started, and enabling gas to flow to the high-pressure container (6) through the air inlet pipe by the booster pump (3);

step 4, the controller (8) controls the heat exchanger (7) and the booster pump (3) to operate, and the temperature and the pressure of the gas in the high-pressure container (6) are measured on line by using the first temperature sensor (4) and the first pressure sensor (5); when the received temperature and pressure signal values reach the set initial values, the controller (8) controls the high-pressure electromagnetic valve (9) to be opened, and the gas enters the convergent nozzle (12) from the high-pressure container (6) through a gas outlet pipeline and then is sprayed out;

step 5, defining variables and initializing i to 1;

and 6, measuring the temperature T of the gas at the inlet of the front end of the convergent nozzle (12) at the ith moment by using the second temperature sensor (10) and the second pressure sensor (11) through the controller (8) in the current period T_nozzle,iAnd pressure P at time i_nozzle,i(ii) a And the temperature T at the ith moment_nozzle,iAnd pressure P at time i_nozzle,iSubstituting the temperature into a gas thermodynamic model to obtain the gas temperature T at the outlet of the convergent nozzle (12) at the ith moment_jf,iAnd actual enthalpy per second

7, the controller (8) actually measures the gas temperature T at the outlet of the convergent nozzle (12) at the ith moment_jf,iWith the desired gas temperature T at the outlet of the convergent nozzle (12)_jf,0Comparing the two to calculate the relative error delta T of the two at the i-th time_jf,iAnd relative error Δ T 'from the set value'_jfComparing; at the same time, the controller (8) will calculate the actual enthalpy per second at the i-th momentEnthalpy per second in relation to the jet field theoryComparing the two to calculate the relative error of the two at the i-th timeRelative error with respect to the setComparing; if Δ T_jf,i|≤ΔT_jf' andassigning the period T +1 to the period T, and returning to the step 6 to execute the sequenceThe cutting process is finished; otherwise, executing step 8;

step 8, the controller (8) is used for controlling the temperature T according to the ith moment of the gas in the high-pressure container (6)_gt,iAnd pressure P at time i_gt,i(ii) a Calculating the temperature demand value T at the i +1 th moment_gt,i+1＝2T_gt,i-T_nozzlet,iAnd a pressure requirement value P_gt,i+1＝2P_gt,i-P_nozzlet,i；

Step 9, assigning i +1 to i;

step 10, the controller (8) controls the heat exchanger (7) and the booster pump (3) to operate, and regulates and controls the temperature and the pressure of the gas in the high-pressure container (6) to respectively reach T_gt,iAnd P_gt,iAnd then, returning to the step 6 to execute the sequence.

2. A method as claimed in claim 1, wherein the gas thermodynamic model of the system in step 1 is established by using equation (1):

in the formula (1), T_jfIs the gas temperature at the exit of the convergent nozzle;enthalpy of gas flowing out per second of the jet field; p_nozzleThe pressure of the gas at the inlet of the front end of the convergent nozzle; t is_nozzleThe temperature of the gas at the inlet of the front end of the convergent nozzle; eta_noIs the efficiency of the convergent nozzle; k is the gas specific heat ratio; r is a gas constant; c. C_pIs the constant pressure specific heat capacity of the gas; a. the_nozzleIs the cross-sectional area at the outlet of the convergent nozzle.

Technical Field

The invention relates to the field of gas cooling metal cutting processing, in particular to a refrigeration parameter regulation and control method for a cooling gas jet field in metal cutting processing.

Background

The gas cooling metal cutting technology is a green cutting technology using gas for cutting. The technology is characterized in that high-pressure gas expands at the outlet of a convergent nozzle, and a low-temperature jet flow field is generated by utilizing the Joule-Thomson effect, so that cutting heat generated by cutting is taken away, and the effect of heat absorption and refrigeration is achieved. The enthalpy, temperature and other parameters of the jet flow field affect the refrigerating capacity during cutting processing, and are difficult to directly measure, and a parametric regulation method is lacked, so that the refrigerating capacity of the gas is difficult to carry out parametric regulation during cutting processing of gas-cooled metal.

Disclosure of Invention

The invention aims to solve the defects of the prior art, and provides a method for regulating and controlling the refrigeration parameters of a cooling gas jet field for metal cutting processing aiming at the gas cooling metal cutting processing technology so as to stably and accurately control the gas temperature at the outlet of a convergent nozzle and the enthalpy of gas flowing out of the jet field per second, thereby improving the stability and accuracy of the jet field and realizing the feedback regulation of the refrigeration capacity.

In order to solve the technical problem, the invention is realized as follows:

the invention relates to a method for regulating and controlling refrigeration parameters of a metal cutting cooling gas jet field, which is applied to a regulation and control system consisting of a gas cylinder, a gate valve, a booster pump, a first temperature sensor, a first pressure sensor, a high-pressure container, a heat exchanger, a controller, a high-pressure electromagnetic valve, a second temperature sensor, a second pressure sensor and a convergent nozzle, wherein the gas cylinder is connected with the booster pump through a conveying pipeline, and the conveying pipeline is provided with the gate valve; the booster pump is connected with the high-pressure container through an air inlet pipeline, a first temperature sensor and a first pressure sensor are arranged in the high-pressure container, and a heat exchanger is arranged on the outer wall of the high-pressure container; the high-pressure container is connected with the convergent nozzle through an air outlet pipeline, a high-pressure electromagnetic valve is arranged on the air outlet pipeline, and a second temperature sensor and a second pressure sensor are arranged at an inlet at the front end of the convergent nozzle; the method is characterized by comprising the following steps of:

step 1, according to the gas temperature T at the outlet of the convergent nozzle required by metal cutting_jf,0Enthalpy of gas flowing out per second of jet field theoryCalculating the temperature demand value T of the gas at the inlet of the front end of the convergent nozzle by combining a gas thermodynamic model at the convergent nozzle_nozzle,iAnd a pressure requirement value P_nozzle,i；

Step 2, opening the gate valve, and enabling gas to flow to the booster pump through the delivery pipe from the gas cylinder;

step 3, the controller sets the initial value T of the temperature of the gas in the high-pressure container_gt,0Initial value of pressure P_gt,0Respectively the temperature demand values T of the gas at the inlet of the front end of the convergent nozzle_nozzle,0And a pressure requirement value P_nozzle,0Controlling the booster pump to be started, and enabling gas to flow to the high-pressure container through the gas inlet pipe by the booster pump;

step 4, the controller controls the heat exchanger and the booster pump to operate, and the temperature and the pressure of the gas in the high-pressure container are measured on line by using the first temperature sensor and the first pressure sensor; when the received temperature and pressure signal values reach the set initial values, the controller controls the high-pressure electromagnetic valve to be opened, and the gas enters the convergent nozzle from the high-pressure container through the gas outlet pipeline and is sprayed out;

step 5, defining variables and initializing i to 1;

and 6, measuring the temperature T of the gas at the inlet at the front end of the convergent nozzle at the ith moment by the controller by utilizing the second temperature sensor and the second pressure sensor in the current period T_nozzle,iAnd pressure P at time i_nozzle,i(ii) a And the temperature T at the ith moment_nozzle,iAnd pressure P at time i_nozzle,iSubstituting into a gas thermodynamic model to obtain the gas temperature T at the outlet of the convergent nozzle at the ith moment_jf,iAnd actual enthalpy per second

Step 7, the controller actually measures the gas temperature T at the outlet of the convergent nozzle at the ith moment_jf,iWith the desired gas temperature T at the outlet of the convergent nozzle_jf,0Comparing the two to calculate the relative error delta T of the two at the i-th time_jf,iRelative error Δ T from the set_j′_fComparing; at the same time, the controller will real enthalpy per second at the ith momentEnthalpy per second in relation to the jet field theoryComparing the two to calculate the relative error of the two at the i-th timeRelative error with respect to the setComparing; if Δ T_jf，i|≤ΔT_jf′And isAssigning the period T +1 to the period T, and then returning to the step 6 to execute the steps sequentially until the cutting process is finished; otherwise, executing step 8;

step 8, the controller is used for controlling the temperature T according to the ith moment of the gas in the high-pressure container_gt,iAnd pressure P at time i_gt,i(ii) a Calculating the temperature demand value T at the i +1 th moment_gt,i+1＝2T_gt,i-T_nozzlet,iAnd a pressure requirement value P_gt,i+1＝2P_gt,i-P_nozzlet,i；

Step 9, assigning i +1 to i;

step 10, the controller controls the heat exchanger and the booster pump to operate, and regulates and controls the temperature and the pressure of the gas in the high-pressure container to respectively reach T_gt,iAnd P_gt,iAnd then, returning to the step 6 to execute the sequence.

The method for regulating and controlling the refrigeration parameters is also characterized in that the gas thermodynamic model of the system in the step 1 is established by using the formula (1):

in the formula (1), T_jfIs the gas temperature at the exit of the convergent nozzle;enthalpy of gas flowing out per second of the jet field; p_nozzleThe pressure of the gas at the inlet of the front end of the convergent nozzle; t is_nozzleThe temperature of the gas at the inlet of the front end of the convergent nozzle; eta_noIs the efficiency of the convergent nozzle; k is the gas specific heat ratio; r is a gas constant; c. C_pIs the constant pressure specific heat capacity of the gas; a. the_nozzleIs the cross-sectional area at the outlet of the convergent nozzle.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, through establishing the convergent nozzle and a thermodynamic model at the jet flow field, a calculation relation can be established between the gas at the inlet at the front end of the convergent nozzle and the gas in the jet flow field. And calculating the gas temperature at the outlet of the convergent nozzle and the enthalpy of the gas flowing out of the jet flow field per second according to the temperature and the pressure of the gas at the inlet of the front end of the convergent nozzle and by combining the thermodynamic model. The invention reflects the refrigeration capacity through enthalpy, quantifies the refrigeration capacity in a parameterization way, and carries out parameterization regulation and control on the temperature and the pressure of the gas at the inlet at the front end of the convergent nozzle. Therefore, the fluctuation caused by the influence of environment, gas outlet pipeline loss and the like is reduced, the stability and accuracy of the jet flow field are improved, and the feedback regulation of the refrigerating capacity is realized.

2. The invention realizes on-line measurement data through the high-pressure container and the temperature sensor and the pressure sensor at the front end inlet of the convergent nozzle, realizes feedback control on the gas temperature at the outlet of the convergent nozzle and the enthalpy of the gas flowing out per second of the jet flow field theory by combining a feedback control system, realizes that the gas temperature at the outlet of the convergent nozzle and the enthalpy of the gas flowing out per second of the jet flow field theory are stabilized near expected values, reduces the fluctuation of the temperature and the enthalpy of the jet flow field caused by the influence of environment, gas outlet pipeline loss and the like, improves the stability of the jet flow field, and realizes the feedback regulation of the refrigerating capacity.

Drawings

FIG. 1 is a schematic diagram of the operation of a method for controlling the refrigeration parameters of a cooling gas jet field in metal cutting;

fig. 2 is an operation step diagram of a refrigeration parameter control method for a metal cutting cooling gas jet flow field according to the present invention.

Detailed Description

In this embodiment, as shown in fig. 1, a method for regulating and controlling refrigeration parameters of a metal cutting cooling gas jet field is applied to a regulation and control system composed of a gas cylinder 1, a gate valve 2, a booster pump 3, a first temperature sensor 4, a first pressure sensor 5, a high-pressure container 6, a heat exchanger 7, a controller 8, a high-pressure solenoid valve 9, a second temperature sensor 10, a second pressure sensor 11, and a convergent nozzle 12;

the gas cylinder 1 is an initial gas source of the system and is used for providing gas for cooling a jet flow field in metal cutting. The gas cylinder 1 is connected with a booster pump 3 through a conveying pipeline, a gate valve 2 is arranged on the conveying pipeline, and the gate valve 2 is used for controlling the on-off of the conveying pipeline; the booster pump 3 is connected with the high-pressure container 6 through an air inlet pipeline, and a switch of the booster pump is used for controlling the on-off of the air inlet pipeline; a first temperature sensor 4 and a first pressure sensor 5 are arranged in the high-pressure container 6, the first temperature sensor 4 is used for measuring the temperature of the gas in the high-pressure container 6, and the first pressure sensor 5 is used for measuring the pressure of the gas in the high-pressure container 6; the heat exchanger 7 is arranged on the outer wall of the high-pressure container 6, and the heat exchanger 7 is used for heating and cooling the gas in the high-pressure container 6; the high-pressure container 6 is connected with the convergent nozzle 12 through an air outlet pipeline; the gas outlet pipeline is provided with a high-pressure electromagnetic valve 9, and the high-pressure electromagnetic valve 9 is used for controlling the on-off of the gas outlet pipeline; a second temperature sensor 10 and a second pressure sensor 11 are arranged at the inlet of the front end of the convergent nozzle 12, the second temperature sensor 10 is used for measuring the temperature of the gas at the inlet of the front end of the convergent nozzle 12, and the second pressure sensor 11 is used for measuring the pressure of the gas at the inlet of the front end of the convergent nozzle 12;

the controller 8 is respectively connected with the booster pump 3, the heat exchanger 7, the first temperature sensor 4, the second temperature sensor 10, the first pressure sensor 5, the second pressure sensor 11 and the high-pressure electromagnetic valve 9 through data transmission lines to form a feedback control system, so that feedback control of the gas temperature at the outlet of the convergent nozzle and the enthalpy of the gas flowing out per second in the jet flow field theory is realized.

As shown in fig. 2, the parameterized refrigeration regulation and control method is performed according to the following steps:

step 1, constructing a gas thermodynamic model of the system in the controller, specifically, the gas thermodynamic model at the convergent nozzle 12 is established by using the formula (1):

in the formula (1), T_jfIs the gas temperature at the exit of the convergent nozzle in K;is the enthalpy of the gas flowing out of the jet field per second, with the unit being kJ/s; p_nozzleThe pressure of the gas at the inlet of the front end of the convergent nozzle is kpa; t is_nozzleThe temperature of the gas at the inlet of the front end of the convergent nozzle is K; eta_noIs the efficiency of the convergent nozzle; k is the gas specific heat ratio; r is a gas constant, and the unit is kJ/(kg. K); c. C_pThe specific heat capacity at constant pressure of the gas is expressed in kJ/(kg. K); a. the_nozzleIs the cross-sectional area at the outlet of the convergent nozzle, and the unit is m². Wherein, the nozzle refers to the inlet of the front end of the convergent nozzle; jf refers to the jetflow jet field.

Gas at the outlet of the convergent nozzle 12 according to the need of metal cuttingBody temperature T_jf,0Enthalpy of gas flowing out per second of jet field theoryCalculating the temperature requirement T of the gas at the inlet of the front end of the convergent nozzle 12 by combining a gas thermodynamic model at the convergent nozzle 12_nozzle,iAnd a pressure requirement value P_nozzle,i

Step 2, opening a gate valve 2, and enabling gas to flow to a booster pump (3) through a delivery pipeline from a gas cylinder 1;

step 3, the controller 8 sets the initial value T of the temperature of the gas in the high-pressure container 6_gt,0Initial value of pressure P_gt,0Respectively, the temperature demand values T of the gas at the inlet of the front end of the convergent nozzle 12_nozzle,0And a pressure requirement value P_nozzle,0Controlling the booster pump 3 to be started, and enabling the gas to flow to the high-pressure container 6 through the gas inlet pipe by the booster pump 3; wherein gt refers to gas tank;

step 4, the controller 8 controls the heat exchanger 7 and the booster pump 3 to operate, and the temperature and the pressure of the gas in the high-pressure container 6 are measured on line by using the first temperature sensor 4 and the first pressure sensor 5; when the received temperature and pressure signal values reach the set initial values, the controller 8 controls the high-pressure electromagnetic valve 9 to be opened, and the gas enters the convergent nozzle 12 from the high-pressure container 6 through the gas outlet pipeline and is then sprayed out;

step 5, defining variables and initializing i to 1;

and 6, setting the value of the feedback regulation and control period T according to the operating characteristics of the booster pump and the heat exchanger on the outer wall of the high-pressure container.

The controller 8 measures the temperature T of the gas at the inlet of the front end of the convergent nozzle 12 at the ith moment by using the second temperature sensor 10 and the second pressure sensor 11 under the current period T_nozzle,iAnd pressure P at time i_nozzle,i(ii) a And the temperature T at the ith moment_nozzle,iAnd pressure P at time i_nozzle,iSubstituting into a gas thermodynamic model to obtain the gas temperature T at the outlet of the convergent nozzle 12 at the ith moment_jf,iAnd actual enthalpy per second

Step 7, the controller 8 calculates the gas temperature T at the outlet of the actual convergent nozzle 12 at the ith moment_jf,iWith the desired gas temperature T at the outlet of the convergent nozzle 12_jf,0Comparing the two to calculate the relative error delta T of the two at the i-th time_jf,iRelative error Δ T from the set_j′_fComparing; while the controller 8 will adjust the actual enthalpy per second at time iEnthalpy per second in relation to the jet field theoryComparing the two to calculate the relative error of the two at the i-th timeRelative error with respect to the setComparing; if Δ T_jf，i|≤ΔT_jf′Assigning the period T +1 to the period T, and then returning to the step 6 to execute the steps sequentially until the cutting process is finished; otherwise, executing step 8;

step 8, the controller 8 controls the temperature T according to the ith time of the gas in the high-pressure container 6_gt,iAnd pressure P at time i_gt,i(ii) a Calculating the temperature demand value T at the i +1 th moment_gt,i+1＝2T_gt,i-T_nozzlet,iAnd a pressure requirement value P_gt,i+1＝2P_gt,i-P_nozzlet,i；

Step 9, assigning i +1 to i;

step 10, the controller 8 controls the heat exchanger 7 and the booster pump 3 to operate, and adjusts the temperature and the pressure of the gas in the high-pressure container 6 to respectively reach T_gt,iAnd P_gt,iAnd then, returning to the step 6 to execute the sequence.

If the metal is cut in the machining process,due to the variation of the process parameters, the desired gas temperature T at the outlet of the convergent nozzle can be adjusted_jf,0Enthalpy of gas flowing out per second of jet field theoryAnd inputting into a regulation and control system, and repeating the steps for operation.

In conclusion, the method aims to realize that the temperature of the gas at the outlet of the convergent nozzle and the enthalpy of the gas flowing out of the jet flow field per second are stabilized near expected values, and parameterize and quantify the refrigerating capacity. And establishing a calculation relation between the gas at the inlet at the front end of the convergent nozzle and the parameters of the gas in the jet flow field by establishing a thermodynamic model at the convergent nozzle and the jet flow field. The controller respectively compares the actual gas temperature at the outlet of the convergent nozzle and the enthalpy of gas flowing out of the jet flow field per second with theoretical values, and then controls the heat exchanger and the booster pump to regulate and control the temperature and pressure of the gas in the high-pressure container, so as to regulate and control the temperature and pressure of the gas at the inlet at the front end of the convergent nozzle and stabilize the temperature of the gas at the outlet of the convergent nozzle and the enthalpy of gas flowing out of the jet flow field per second near expected values; the enthalpy reflects the refrigerating capacity, quantifies the refrigerating capacity in a parameterization mode, realizes the feedback control of the gas temperature at the outlet of the convergent nozzle and the enthalpy of gas flowing out of the jet flow field per second by combining a feedback control system, reduces the fluctuation caused by the influence of the environment, the loss of a gas outlet pipeline and the like, improves the stability and the accuracy of the jet flow field, and realizes the feedback regulation of the refrigerating capacity.