Abstract
The overall cold forging process of the umbrella gear shaft provided by the present invention relates to the field of metal mechanical processing and metal stamping with basically no cutting, especially the overall plastic precision forming method of the umbrella gear shaft. The process steps are as follows: first, circular steel bars are sawed and then spheroidized and annealed, followed by machining and processing of the billet, followed by phosphorus saponification treatment. Then, the shaft part is extruded, and the rough tooth part is pre upset into a spherical shape, followed by spheroidized annealing and phosphorus saponification treatment. Finally, the teeth are extruded into shape, and the square is extruded into shape. By using the method provided by the present invention, the metal streamline of the product is continuously distributed in its shape, and the internal structure is dense, making the tooth surface of the bevel gear more wear-resistant and durable. The strength of the shaft is more than twice that of the original production process. Meanwhile, due to the absence of material loss during the cold forging process from billet to finished product, it saves materials and reduces energy consumption compared to machining processes. Due to the use of advanced 3D modeling software for cold forging during the development of new products, a significant amount of mold development and debugging time has been saved, reducing development costs.
Description
Cold forging process for umbrella gear shaft as a whole
technical field
The present invention relates to the field of metal mechanical processing and metal stamping with minimal cutting, particularly to a method for integral plastic precision forming of bevel gear shafts.
Background technology
There are two methods for processing existing bevel gear shafts: the first method is to assemble the processed bevel gear onto the processed shaft. The assembly methods can include interference fit, spline fit, flat key with snap spring, etc. The main defects of the bevel gear shaft processed by this method are low transmission strength, and the process method also has the disadvantages of high consumables and energy consumption; The second type is the processing technology of integral casting of umbrella gear shafts. The main defects of umbrella gear shafts processed by this method are reduced accuracy, low yield, and lower strength of castings compared to machined parts. In addition, the above two processing methods also have defects such as long product development time and high development costs.
Summary of the invention
The purpose of the present invention is to overcome the above-mentioned defects and provide a cold forging process for umbrella gear shafts with good wear resistance and high transmission strength.
The technical solution of the present invention is the overall cold forging process of the umbrella gear shaft, which involves the following steps: first cutting, then spheroidizing and annealing, followed by machining and processing of the billet, followed by phosphorus saponification treatment, then normal extrusion of the shaft part, pre upsetting of the coarse tooth part, spheroidizing annealing and phosphorus saponification treatment, followed by tooth extrusion forming, and finally square extrusion forming.
Using the above technical solution, the metal material is pressurized in the mold cavity at room temperature to flow and form. The metal streamline is continuously distributed according to its shape, and the internal structure is dense, making the tooth surface of the bevel gear more wear-resistant and durable. The strength of the shaft is more than twice that of the original production process. At the same time, due to the minimal loss during the cold forging process from billet to finished product, it saves materials and reduces energy consumption compared to machining processes. Due to the use of advanced 3D simulation molding software to simulate cold forging during new product development, a significant amount of mold development and trial production time has been saved, reducing development costs.
Attached image description
Figure 1 shows the shape change of the product during the processing of the present invention.
Figure 2 shows the process flowchart of the present invention.
The present invention will be described in detail with reference to the accompanying drawings.
Specific implementation method
Based on product performance: hardness HRC36-47.5
Tensile strength 1150-1540 Newtons per square millimeter
The product technical parameters are: umbrella gear module 4
Number of teeth 12
Pressure angle 20 °
Axis angle 90 °
Taking the overall cold forging process of umbrella gear shaft with precision level (GB11365-89/8) as an example.
Firstly, based on the 3D simulation forming software, the cold forging process is simulated, and the mold making and material preparation are designed. The raw material for the umbrella gear shaft in this embodiment is 20CrMnTi round steel bar material. The process steps are:
1. Cut 20CrMnTi round steel bars and ensure that the weight of the raw material is 8-12% greater than the weight of the finished product after cutting;
2. Perform spheroidization annealing on the raw material blank, control the heating temperature to 720 ℃ -740 ℃, hold for 3-4 hours, cool it in the furnace to ≤ 500 ℃, and then air cool it out of the furnace. Control the annealing hardness to 70-85HRB;
3. Machining of raw materials to remove surface oxide skin and ensure that the weight of the raw material is consistent with the weight of the finished product;
4. The specific method for phosphorus saponification treatment is as follows: acid washing at liquid temperature of 50-60 ℃ for 5-10 minutes, rinsing with water for 1-2 minutes; Liquid temperature phosphating at 70-80 ℃ for 10-15 minutes, rinse with clean water for 1-2 minutes; Liquid temperature saponification at 80-95 ℃ for 8-10 minutes;
5. The positive extrusion shaft is used to form the shaft head of the umbrella gear shaft, and the diameter and length dimensions of the shaft head are controlled. The diameter is 0.2-0.5mm smaller than the finished product diameter, and the length is 1-2mm shorter than the finished product length;
6. Pre upsetting the gear teeth into a spherical shape, controlling the diameter and length dimensions of the shaft head, as well as the weight of the upsetting ball part, to ensure that the diameter of the shaft head meets the finished product size, reserving the length for the next process of square extrusion elongation, and ensuring that the weight of the upsetting ball part is 5-10% heavier than that of the finished gear teeth;
7. Spheroidization annealing, controlled heating temperature of 720 ℃ -740 ℃, holding for 3-4 hours, cooled in the furnace to ≤ 500 ℃ and then air cooled out of the furnace, controlled annealing hardness of 70-85HRB;
8. The specific method for phosphorus saponification treatment is as follows: acid washing at liquid temperature of 50-60 ℃ for 5-10 minutes, rinsing with water for 1-2 minutes; Liquid temperature phosphating at 70-80 ℃ for 10-15 minutes, rinse with clean water for 1-2 minutes; Liquid temperature saponification at 80-95 ℃ for 8-10 minutes;
9. Regularly check the roughness and adequacy of the gear tooth surface after the positive extrusion of the bevel gear tooth profile. If there is gear pulling or excess material on the tooth bottom surface, the mold needs to be repaired or replaced in a timely manner;
10. The square head at the top of the umbrella gear is processed using the reducing extrusion method, and the diameter and length of the square are controlled to meet the requirements of the finished product size.
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