1. Introduction
As is well known, the cost of die casting is concentrated in the cost of mold manufacturing, which is an explicit cost. However, for a company's profitability, the cost of molds has already been invested, and the profitability is more focused on the output of qualified products produced by die casting. Especially now, with the rise of technology and new energy vehicles, the demand for high-pressure die casting large tonnage machines is increasing.
Previously, the tonnage of press machines was generally between a few hundred to over a thousand tons, and over two thousand tons was considered a large machine. With the initial enthusiasm for 5G in the field of communication, communication products have rapidly increased in size from ordinary 200-300mm to 600-700mm or even 1000mm, and the requirements for the tonnage of die-casting machines have increased from 2000T to 3000T and then to 4500T. At the same time, stimulated by the "Tesla integrated frame" in the new energy field, considering the requirements for cost reduction and efficiency improvement of new energy structural components, more car companies have invested funds in integrated die-casting, and the die-casting tonnage has exceeded 4500T and entered 6000T, even 8800T and even larger tonnage.
For large tonnage presses, the output rate directly affects the profitability of the product. In addition to conventional mold casting design, mold temperature also has a significant impact on die-casting production and product qualification rate. How to effectively control and utilize mold temperature to improve product qualification rate is a crucial aspect of enterprise profitability. To effectively control the mold temperature, the first step is to focus on mold design. Next, we will analyze the control of mold temperature in design from the perspective of mold design.
2. How to consider mold temperature in mold design
2.1 Design considerations for mold companies
With the integration of die-casting, more die-casting enterprises are starting to have their own mold companies or long-term cooperative mold companies, which is conducive to controlling the mold production cycle and mold maintenance. Moreover, one's own mold company or long-term cooperative mold company is more familiar with the actual production situation of their own enterprise, and can better match the actual usage situation in mold design, thereby making the mold more suitable for die-casting production in the enterprise.
The core of a mold design company is still people, and the experience of designers has a great impact on mold design. Fortunately, for mold design, in addition to direct design by personnel, enterprises have also introduced internal reviews of mold design units, which work together with production enterprises to review the plan. At the same time, combined with the simulation effect of mold flow, the plan can be adjusted in a timely manner. It is equivalent to closely combining software simulation conclusions, design think tank experience, and actual production think tank experience and lessons learned.
2.2 Considerations for mold temperature control
The current mold temperature design is mainly used as a supplement to the pouring scheme, and personnel's experience is more at the macro level of the pouring channel. However, for factors such as mold temperature that cannot be directly judged and adjusted with the naked eye, it is still relatively "empty". Instead, it is more important to use simulation results from software such as mold flow analysis as a reference.
The simulation of software should only be used as a reference, and the mold temperature is not always at a fixed value during the actual production process. Our design is to make the range of this value in software simulation wider and more conducive to our production. The temperature control factors in actual production need to be adjusted according to different usage sites and situations, and mold designers should consider a range that we can effectively control in actual production, so as to simulate the effect through software. Adjusting the pouring arrangement and other factors is beneficial for mold design in production.
2.3 Mold design considerations for mold temperature on mold temperature machines
Nowadays, water temperature machines or oil temperature machines are commonly used for heating molds. However, for the requirements of heating molds, process personnel tend to choose oil temperature machines. Designers should evaluate whether conventional oil temperature machines can be used based on the needs of process personnel, as well as the brand and specifications of the oil temperature machines actually used in the production workshop (to facilitate replacement and replacement on the production site). At the same time, the evaluation of the oil temperature machine should take into account factors such as the specifications and heating rate of the oil temperature machine.
2.4 Layout considerations for mold temperature pipelines in mold design
The management layout of mold temperature initially comes from the experience of designers and the characteristics of product structure, combined with simulation results to make relevant adjustments. This is a product, and different molds will consider different matters. This analysis is not within the scope of our discussion today. This article mainly discusses how to control the mold temperature. In most cases, the mold area is different, and the heat absorption is different. By adjusting different flow rates, rates, and temperatures, the mold temperature can be balanced.
When we actually make molds, we often use a universal mold temperature channel. For example, they are all designed φ The 10mm channel has the same channels everywhere on the mold. We all know that in actual production, the temperature in the inlet area will be higher, and the temperature above the mold will be lower. If it involves the slider, the temperature will also be different for different positions of the slider, and the temperature of the slider and the mold will also be different for the same position. If that's the case, how could we still use the same channel? At this point, we need to consider the difference in heat to determine the arrangement of different sizes of mold temperature pipes, design them as a series of one or one, two or more, and choose different mold temperature machine specifications to quickly achieve balance in the production process.
2.5 considerations for actual pipeline conditions in mold design
The actual layout of the press, unless it is a specialized machine, is generally fixed in position. Even for specialized machines, it is difficult to directly place the mold temperature machine next to the mold, especially for large tonnage presses, where the mold temperature machine is generally more than five meters away from the mold. But this will face a practical problem. When the displayed oil temperature value of the mold temperature machine actually reaches the mold, there is a cooling effect, while the return oil temperature value is actually lower than the temperature on the mold. Therefore, for actual control of mold temperature, there is already a range value.
When we control this interval value, we actually increase the actual temperature control interval value. And we found during the production of large tonnage molds that due to the weight of the molds themselves being 50-60 tons, the temperature rise of the mold temperature machine is very slow, and it takes several hours for the temperature to improve. At this time, we must consider the supply capacity of the mold temperature machine. For example, our set of mold temperature machines can accommodate 10L of oil, while the pipeline designed for the mold needs to accommodate 5L. The outlet and return pipes of the mold temperature machine need to occupy 3L of oil, so in reality, only 2L of oil can be used for heat exchange in the mold temperature machine; The other set of mold temperature machines can accommodate 10L of oil, while the pipeline designed for the mold needs to accommodate 3L. The outlet and return pipes of the mold temperature machine need to occupy 3L of oil. In fact, 4L of oil can be used for heat exchange in the mold temperature machine. The heat exchange between the two sets is unequal, which affects the control of mold temperature. Therefore, these factors must be taken into consideration in the initial design.
3. Conclusion
Based on the above analysis, in the early stage of mold temperature design, the influence of mold temperature flow rate and the distance between the inlet and return pipelines on the dissipation of mold temperature, as well as the occupation of oil quantity by pipelines, were considered. These situations should be considered in the mold design according to the actual situation of use, in order to design suitable mold temperature pipelines and configuration requirements, simplify mold temperature control in subsequent actual production, and improve the stability of internal product quality. These are very important for corporate profitability.
Text: Zhang Jie from Chongqing Meilixin Technology Co., Ltd
