How to solve the problems in the processing of sprocket shaft parts

AgainstSprocketFor the problems in the processing of shaft parts, the processing plan is improved, and the combined processing method is adopted, which reduces the processing difficulty and processing cost, meets the size and accuracy requirements of the parts, and improves the processing efficiency.

  The main function of the shaft is to support the transmission parts (gear,SprocketThe main structural feature is that the length is greater than the diameter, and it is generally composed of a concentric outer circle, a cone, an inner hole, a thread and a keyway.

 1. Analysis of part structure and processing difficulties

  SprocketThe shaft is a slender shaft of the drying furnace sprocket transmission mechanism in the SPL-1200 printing system of our equipment, made of 45 steel, quenched and tempered (T215).The diameter of the part is 30mm, the length is 1 171mm, and the aspect ratio is 39. It is a slender shaft with poor rigidity.The processing requires the dimensional accuracy of both ends to be φ 30 0-0.009mm, the coaxiality of the outer circle of both ends of φ 3 0 mm to be 0.02mm, and the surface roughness Ra=1.6μm.

  From the structure of the sprocket shaft, it can be seen that its biggest feature is poor rigidity. During the processing, factors such as cutting force, cutting heat and vibration will affect the dimensional accuracy and shape and position accuracy of the processing, and the processing is difficult.This part needs 18 pieces for a single product. If the conventional processing method is used, the processing cycle is long, and it is difficult to meet the processing requirements, which will easily lead to the scrapping of the parts, and affect the product delivery cycle and increase the processing cost.

  2. Problems in processing

  During the trial production of the sprocket shaft, the conventional processing method is adopted, and the processing process is as follows: (45) Blanking. 35 steel, blank size φ 1mm×180 30mm. ② heat treatment.Material conditioning treatment.Restricted by the heat treatment process, the quenching and tempering treatment is done externally. ③ car.Except for the outer circle wear amount of φ 30mm at both ends, the rest of the parts are adjusted to the size. ④ Milling.Mill keyways at both ends. ⑤ car.Repair the center hole at both ends. ⑥ Cylindrical grinding.The outer circle of φ XNUMXmm at both ends of the top grinding meets the requirements of the pattern size. ⑦Surface treatment.Black oxidation treatment.

  Because the sprocket shaft is a slender shaft, the rigidity of the parts is poor, and the structural manufacturability is not good. During turning, it is affected by factors such as cutting force, clamping force, self-gravity, cutting heat and vibration, and the following problems will occur during processing:

  (1) The resultant force of the radial cutting force generated during cutting and the radial component force of the clamping will bend the workpiece and cause vibration when the workpiece rotates, thereby affecting the machining accuracy and surface quality.

  (2) When the workpiece rotates at high speed, the bending and vibration of the workpiece are aggravated due to the centrifugal force.

  (3) Due to the self-weight deformation of the workpiece, the natural vibration of the workpiece is aggravated, which affects the machining accuracy and surface quality.

  (4) The quenching and tempering treatment of the steel causes the bending deformation of the blank, which seriously affects the subsequent turning processing, and needs to be straightened, which increases the processing cost.

  If optical shaft processing is selected, the processing process of the sprocket shaft becomes: ①Order the grinding optical rod to ensure the dimensional tolerance. ②Empty knives and chamfers around the car. ③ Mill the keyway at both ends. ④Surface oxidation treatment.This method is not ideal because the dimensional tolerance of the optical axis cannot reach the requirement of 0.009mm, and the surface hardness of the chrome-plated optical axis can reach 45HRC, which makes the subsequent keyway processing difficult.

  3. Solutions

  In view of the problems in the processing of the sprocket shaft, according to the structural characteristics and use requirements of the parts, a combined welding processing plan is considered.

  根据零件的结构特点把零件拆分为3部分,如图2、图3所示。图2为组合焊接图,图3为拆分件。将链轮轴拆分成3部分组焊而成。中间部分选用45钢光轴,该部分加工工艺过程为: 定购φ 30mm光棒→车两端面,车两端焊接工艺沉孔并倒焊接坡口。

  The outer circle of φ 3mm at both ends has precision requirements, and some parts are made of 0 steel blanks. The processing process is as follows: ① Blanking.Material 45 4 steel, blank size φ 5mm×35mm. ② heat treatment.

  Material conditioning treatment. ③ car.The two ends of the car meet the size requirements; the center hole is drilled, and the outer circle of the top car is φ 30mm to retain the wear amount; the car ring groove is sized; the car is out of the welding positioning process handle, and the welding groove is reversed. ④ Mill keyway. ⑤ car.Repair the center hole at both ends. ⑥ Cylindrical grinding.Double top, grinding the outer circle of φ 30mm to meet the requirements of the pattern size.

  After the disassembled parts are processed according to the pattern, assemble the middle part and the two end parts together, take the center hole at both ends as the positioning reference, and use argon arc welding according to the pattern in the double top clamping state. ).

1. Fixed support 2. Front top 3. Sprocket shaft 4. Rear top 5. Adjusting support 6. Welding platform

  In order to reduce welding deformation, the method of preheating and layered welding can be used, the workpiece is evenly rotated on the positioning tool, and the welding is evenly welded along the welding port. .Before welding, it is required to straighten the light rod, and use argon arc welding to continuously weld firmly and reliably. After welding, ensure that the coaxiality of φ 30mm at both ends is not greater than 0.04mm, and smooth the weld to protect the surface of the parts.