阅读说明：本技术 一种基于体系热平衡技术的模具温度控制方法 (Mold temperature control method based on system heat balance technology ) 是由 王开 王琳锐 胡盛情 何乃军 邱孝祥 于 2021-08-03 设计创作，主要内容包括：本发明公开了一种基于体系热平衡技术的模具温度控制方法,运用体系热平衡原理,结合数值计算、在线测控方法调控模具温度场,实现对铸件冷却条件的准确调控。其特征包括如下步骤：首先,分析铸件冷却条件,获得铸件的温度场；然后,结合界面换热条件和体系传热,获得模具温度场；其次,结合铸造过程的温度场演变规律,获得模具的温度场演变规律；再次,明确模具测试温度点的温度演变函数；最后,运用模温控制手段,调控模具温度场分布,实现对铸件冷却条件的调控。采用本发明能够更准备的控制铸件冷却条件,减少凝固收缩类缺陷,达到提高铸件性能的目的。(The invention discloses a mold temperature control method based on a system heat balance technology, which is used for accurately regulating and controlling the cooling condition of a casting by using a system heat balance principle and combining numerical calculation and an online measurement and control method to regulate and control a mold temperature field. The method is characterized by comprising the following steps: firstly, analyzing the cooling condition of the casting to obtain the temperature field of the casting; then, combining the interface heat exchange condition and system heat transfer to obtain a mold temperature field; secondly, combining a temperature field evolution law in the casting process to obtain a temperature field evolution law of the mold; thirdly, defining a temperature evolution function of the mold testing temperature point; and finally, regulating and controlling the temperature field distribution of the die by using a die temperature control means to realize the regulation and control of the cooling condition of the casting. The invention can control the cooling condition of the casting, reduce the defects of solidification shrinkage and achieve the aim of improving the performance of the casting.)

1. A mold temperature control method based on a system heat balance technology is characterized by comprising the following steps:

firstly, obtaining the cooling behavior of the die cavity casting under the optimized process condition by adopting a numerical simulation method, and analyzing the temperature field change of the die cavity casting in the forming process;

then, measuring the heat exchange of the casting interface and the variable of the die material by combining an experiment, calculating to obtain the temperature distribution of the die, and verifying the temperature field of the die by combining the experiment;

secondly, based on the mold opening and closing process of production, the change condition of the mold heat in the whole process cycle process is calculated through numerical simulation, the change rule of the temperature of the test point in the thickness direction of the mold along with time is determined, and the mold temperature field evolution rule in the casting process is predicted;

thirdly, determining a characteristic temperature testing position in the thickness direction of the mold according to the structural characteristics and the solidification behavior of the mold cavity, extracting the temperature change rule of the characteristic point along with time, and taking the temperature change rule as a temperature change function of the mold temperature testing point;

and finally, controlling the temperature and heat distribution of the die in the process circulation process by adopting a die temperature cooling system and taking the temperature control of the characteristic temperature test position in the thickness direction of the die as a target to realize the regulation and control of the cooling condition of the casting.

The technical field is as follows:

the invention belongs to the technical field of casting, and particularly provides a mold temperature control method based on a system heat balance technology.

Background art:

the casting refers to a production method that liquid alloy is poured into a cavity with a shape and a size suitable for a part, and a blank or the part is obtained after the liquid alloy is cooled and solidified. The casting has the characteristics of high production efficiency, flexible process, low cost and the like, and is widely applied in the industrial field. However, the level of process control in the casting process directly affects the product quality. In the process of alloy solidification, the isolated melt area will finally form shrinkage cavity and shrinkage porosity defects, which seriously affect the compactness and mechanical properties of the product.

In the casting production process, the heat transmitted by cooling, solidifying and transmitting the alloy liquid is absorbed and emitted by the die, so that the cooling and solidifying of the alloy liquid or the final casting product is realized. Differences in the cooling conditions of the alloy liquid, including cooling rate, temperature gradient, etc., seriously affect the solidification structure and casting performance characteristics of the casting. In order to improve the stability and consistency of the quality of the castings, the stability and consistency of the raw materials and the overall manufacturing process are improved. The regulation and control of the internal shrinkage defects of the casting requires strict control of the temperature of a mold cavity system, and particularly, the mold temperature of the casting periodically changes corresponding to the production cycle in the continuous production process. In the actual production process, a mold temperature heating system, a mold temperature cooling system and the like are often adopted to regulate and control the heat distribution of a mold cavity system, and the cooling condition of the casting is controlled to achieve the purpose of controlling the internal quality of the casting. In a mold temperature control system and a mold temperature control method (application number: CN201310268425.6), a mold temperature control method is introduced, which realizes rapid and uniform temperature rise of a mold by comparing the average temperature of a heating pipe with a calibration temperature and the single-point temperature of a mold cavity with the calibration temperature. Although the temperature distribution of the die can be improved by regulating and controlling the temperature, the periodic stable change of the die temperature can be realized only after the die cavity system works for a long time to reach the heat balance, and finally the consistency of the quality of the casting product is realized. Obviously, the temperature is only one measurement parameter which indirectly reflects the heat change, and the simple temperature point detection technology is difficult to stably regulate and control the heat dissipation behavior of the mold cavity.

Based on the above, a better mold temperature measurement and control means is urgently needed to be developed so as to obtain reasonable mold temperature field distribution and heat dissipation conditions, and further meet the mold temperature control requirement of high-stability casting product production.

The invention content is as follows:

the invention aims to provide a mold temperature control method based on a system heat balance technology, which can be used for controlling the temperature and heat distribution of a casting mold more conveniently, stably regulating and controlling the cooling condition of a casting and realizing the stability and consistency of the production quality of the casting.

The technical scheme of the invention is as follows:

a temperature control method of a die based on a system heat balance technology comprises the following steps of firstly, obtaining a cooling condition of a casting in a die cavity under an optimized process condition according to a numerical simulation method; secondly, combining the experiment to measure the heat exchange variable of the casting interface to obtain the temperature distribution of the die cavity system, and combining the experiment to verify the prediction result of the temperature field distribution of the casting; then, based on the mold opening and closing process of casting production, the change condition of the mold heat in the whole process cycle process is calculated through numerical simulation, the change condition of the mold temperature distribution is determined, and a predicted temperature curve is obtained; thirdly, determining a characteristic temperature testing position in the thickness direction of the mold according to the structural characteristics of the mold cavity, extracting the temperature change rule of the characteristic point, and using the temperature change rule as a temperature testing point of the mold; and finally, controlling the temperature of the mold in the casting process circulation process by combining a mold cooling system and taking the temperature control of a plurality of characteristic points in the thickness direction of the mold as a target parameter.

The invention has the beneficial effects that:

1. based on the heat conservation principle, the temperature distribution of the die system is obtained by adopting a heat transmission calculation method, the die heat transfer cooling conditions in the casting process are ensured, and the consistency of the casting cooling conditions is ensured.

2. The method is characterized in that a change function relation of the temperature field of the die along with time in the production cycle process is established, and the purpose of controlling the distribution of the temperature field of the die is achieved by utilizing a regulation and control method of the integral heat of the die, so that the method has higher reliability.

Description of the drawings:

fig. 1 is a flow chart of a method for controlling and regulating a mold temperature field, and fig. 2 is a graph showing a change of temperature of a characteristic point close to the inner surface of a mold with time in a single forming cycle period.

The specific implementation mode is as follows:

the present invention will be described in further detail with reference to examples.

Referring to fig. 1 and fig. 2, the method for controlling the temperature of the mold based on the system thermal equilibrium technology provided by the invention comprises the following working steps:

analyzing the temperature field of the casting. Obtaining the cooling condition of the die cavity casting under the optimized process condition according to a numerical simulation method;

and calculating and verifying the temperature field of the mold. Obtaining the temperature distribution of the die by combining the heat exchange variable of the interface of the casting measured by the experiment, and verifying the temperature field distribution of the casting by combining the experiment;

and thirdly, predicting the temperature evolution of the die in the casting process. Based on the mold opening and closing process of production, the change condition of the mold heat in the whole process cycle process is calculated through numerical simulation, the change condition of the mold temperature distribution along with time is determined, and the mold temperature evolution law in the process is predicted;

and fourthly, testing a temperature change function of the mold temperature. Determining a characteristic temperature testing position according to the structural characteristics and the solidification behavior of the cavity, extracting the temperature change rule of the characteristic point in the thickness direction of the mold, and obtaining the temperature-time function of the temperature testing point of the mold;

and (6) dynamically regulating and controlling the temperature of the die. And controlling the temperature of the die in the process circulation by taking the temperature-time function of the plurality of characteristic points as a control target parameter in combination with a die temperature cooling system.

Example 1

Taking the low-pressure casting of the aluminum alloy oil bottom shell as an example, firstly, adopting Anycasting casting simulation software to carry out optimization design on the casting process of the casting, and investigating the relationship between the heat distribution and the temperature change along with time in the cooling and solidification process of alloy melt filled in a cavity; secondly, obtaining temperature distribution of different positions of a casting and a die in the low-pressure casting process and a change relation of the temperature distribution and the change relation with time in the production process by adopting an experimental method, obtaining an interface heat exchange coefficient variable in the casting process, obtaining a change rule of a die temperature field according to a heat balance calculation method, and optimizing a boundary heat exchange model according to an experimental result; then, based on the production links of die sinking, spraying, die assembly, pouring, cooling and the like in the low-pressure casting process, the change condition of the die heat in the whole process is obtained by using a simulation calculation tool, the change condition of the die temperature distribution is clarified, and a predicted temperature-time curve is obtained and verified; thirdly, according to the structural characteristics of the casting and the temperature distribution near the thermal node, determining and selecting a temperature testing characteristic position, extracting a temperature-time function of the characteristic point, and using the temperature-time function as a mold temperature testing point to detect temperature change; finally, thermocouples are arranged on the plurality of temperature test points in the thickness direction of the mold, the change of the temperature along with the time is detected in real time and is compared with the predicted temperature values of the test points, and the temperature-time function of the plurality of test points is taken as a control target parameter by combining a mold cooling system to regulate and control the temperature distribution of the mold in the process circulation process. By controlling the distribution of the temperature field of the die by the method, the production stability of the casting product is improved by 20 percent.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.