The Improvement Plan for Forged Copper Valves

Forged copper valves are a popular choice in various industries due to their durability, strength, and resistance to corrosion. These forged copper valves are manufactured using a forging process that involves shaping the copper into the desired form through intense heat and pressure. In contrast, traditional valves are typically made from cast iron or steel. One key advantage of forged copper valves is their superior strength. The forging process aligns the grain structure of the metal, making it denser and stronger compared to cast valves. This enhanced strength allows forged copper valves to withstand high-pressure applications without deformation or failure. Furthermore, forged copper valves exhibit excellent corrosion resistance. Copper has natural anti-corrosive properties, making these valves ideal for use in environments where exposure to moisture or chemicals is common. Cast iron or steel valves, on the other hand, may require additional coatings or treatments to protect against corrosion.
 
Part of the copper valve body is relatively complex and cannot be formed using ordinary Half molds or upper and lower flat molds. This may cause cold insulation or folding inside the valve body, especially for materials with poor fluidity. If forging is used, half mold or flat mold should be adopted to achieve a forging die without inherent quality risks. The new red punch die mentioned in this article can meet the requirements for forging for this type of valve body.
 
3. Preliminary improvement plans
In view of the difficult molding of arsenic brass or silicon brass due to poor flow, appropriately control the contents of copper elements, arsenic elements and silicon elements within a certain range, and minimize the impurity content. At the same time, control the hardness of the raw material copper to 100 to 105HB, not exceeding 120HB, or it will aggravate the risk of cracking at the end of the valve body. When heating the red punch, appropriately set a red punch temperature of 650°C to 680°C, which is beneficial to forging. The pass rate of the forged valve body can be higher by taking these modification measures, but it cannot fundamentally eliminate serious inherent cold isolation.
 
Taking advantage of the different flow properties of the material, the restrictions on the material flow caused by the up-and-down core-pulling of Half mold were analyzed, and the structure of the closed up-and-down flat mold was improved, as shown in Figure 3. If you need to forge a more complex Y-shaped valve body as shown in Figure 1, place the copper rod directly in the middle or upper part of the mold cavity. During stamping, the pressure will squeeze the material to all sides. This method will reduce the impact of small sizes of the middle part of the Y-valve on the raw material copper rod. Extruding the material through pressure on the entire shape requires continuous testing, analysis and adjustment of the diameter and amount of raw material until the most reasonable copper rod size is achieved to control the thickness and length of flash, thereby avoiding defects such as folding caused by excess material flanging to the outer surface of the valve body in the extrusion process.
 
This upper and lower flat mold is also called a semi-open flat mold, and the materials used need to be strictly controlled to avoid folding caused by excessive flash. Judging from the current test results, the semi-open flat mold can only be used for brass with relatively low copper content (57.0%  to 59.0%) and good fluidity, such as HPb59-1, HPb58-2, HPb59-3 , C37700 or CW617N. Otherwise, defects such as cold insulation or folding may occur from time to time as shown in Figure 2.
 
For more complex Y-shaped valve bodies made of special arsenic brass or silicon brass, the space of the mold cavity is improved based on the semi-open flat mold, and a certain area outside the valve body roughness is milled. Leave more space for flash and remaining materials, as shown in Figure 4 and Figure 5. This type of mold structure is also called a fully open flat mold. In the forging or red punching process, the remaining material can be directly discharged into this space to avoid the raw material remaining in the mold cavity being flanged and folded on the surface or end face of the valve body due to insufficient space for material running, the hidden quality hazards of the cold insulation that cannot be discovered after processing or destruction testing, and ensure the forging time cycle of the valve body.
 
4. Effective improvement plans
 
 
Figure 4 Open upper and lower flat molds
 
 
Figure 5 The fully open upper and lower flat mold
 
5. Conclusion
The commonly used Half mold can meet the requirements for the forging of valve bodies and valve bonnets with simple shapes. The semi-open flat mold can be used for the forging of brass valve bodies and valve bonnets with more complex shapes that require good material fluidity. However, the fully open flat mold can be used for forging special brass with a complex appearance and structure and poor investment fluidity. Although the raw material investment is great and the internal processing allowance is great, it can fundamentally solve the problems of serious defects of other forging methods like cold insulation. The is also a significant improvement from casting to forging. It is a leap in the upgrading of current forging molds.
 

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