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Machining technology of shaft parts.

1. The function, structural characteristics and technical requirements of shaft parts.

Shaft parts are one of the typical parts that are often encountered in machines. It is mainly used to support transmission parts, transmit torque and bear loads. Shaft parts are rotating body parts, the length of which is greater than the diameter, and are generally composed of the outer cylindrical surface, conical surface, inner hole and thread of the concentric shaft and the corresponding end face.

According to the different structural shapes, shaft parts can be divided into optical shafts, stepped shafts, hollow shafts and crankshafts.

Shafts with an aspect ratio of less than 5 are called minor shafts, and those with more than 20 are called slender shafts, and most shafts fall in between. The shaft is supported by a bearing, and the shaft segment that fits with the bearing is called the journal. The journal is the assembly benchmark of the shaft, their accuracy and surface quality are generally high, and its technical requirements are generally formulated according to the main function and working conditions of the shaft, usually with the following items:

a) Dimensional accuracy.

In order to determine the position of the shaft, the supporting journal usually requires a high degree of dimensional accuracy (IT5, IT7). The dimensional accuracy of the journal for assembling transmission parts is generally low (IT6, IT9).

2) Geometric accuracy.

The geometric accuracy of shaft parts mainly refers to the roundness and cylindricity of the journal, outer cone, Morse taper, etc., and its tolerance should generally be limited to the dimensional tolerance. For the inner and outer circular surfaces with high precision requirements, the allowable deviation should be marked on the drawing.

3) Mutual position accuracy.

The position accuracy requirements of shaft parts are mainly determined by the position and function of the shaft in the machine. Generally, the coaxiality requirements of the journal of the assembly transmission parts should be ensured to support the journal, otherwise the transmission accuracy of the transmission parts (gears, etc.) will be affected and noise will be generated. For shafts of ordinary precision, the radial runout of the supporting journal by the matching shaft segment is general, and the high-precision shaft (such as the main shaft) is usually.

4) Surface roughness.

Generally, the surface roughness of the shaft diameter matched with the transmission part is, and the surface roughness of the supporting shaft diameter matched with the bearing is.

The box is mainly composed of planes and holes, which are also its main faces. Processing the plane first, and then processing the hole, is the general law of box processing. Because the main plane is the assembly datum of the box to the machine, the main plane is processed first, and then the support hole is processed, so that the positioning datum coincides with the design datum and the assembly datum, so that the error caused by the datum does not coincide is eliminated.

In addition, the hole is used as the rough datum to process the plane, and then the plane is used as the fine datum to process the hole. In this way, it can provide a stable and reliable positioning reference for the machining of the hole, and the hard skin and uneven part of the casting are removed when machining the plane, which is conducive to the processing of the subsequent hole, can reduce the deviation of the drill bit and the chipping, and is more convenient for tool adjustment.

2) Rough and finishing in stages.

The principle of separation of roughing and finishing: for boxes with poor rigidity, large batches and high precision, general roughing and finishing are carried out separately, that is, the main plane and the support hole are roughed first, and then the main plane and the support hole are finished. In this way, the influence of internal stress, cutting force, cutting heat and clamping force caused by roughing on machining accuracy can be eliminated, which is conducive to the reasonable selection of equipment.

Separating roughing and finishing increases the number of machines and fixtures, increases the number of workpieces installed, and thus increases costs. Therefore, for single-piece, small batch, and boxes with low precision requirements, roughing and finishing are often combined into one, but corresponding measures must be taken to reduce the deformation in the processing process. For example, after roughing, the workpiece is loosened to allow the workpiece to cool sufficiently, and then finished with a small clamping force and a small amount of cutting.

3) Reasonable arrangement of heat treatment process.

In order to eliminate the internal stresses in the casting, after the blank casting, and sometimes even after the semi-finishing process, artificial aging treatment is carried out to eliminate the residual casting internal stresses and the internal stresses generated during the cutting process. For particularly delicate housings, a long natural aging time should be arranged during the machining process (e.g. coordinate boring machine headstock). In addition to heating and insulation, the artificial aging method of the box can also use vibration aging.

In addition to the parts drawing, there is also an important condition for the development of the process is the production batch, you did not give, so you have to take a single piece, a small batch as an example;

1. Since there is no requirement for heat treatment and hardness, the blank is made of seamless steel pipe, 260*760mm, 2, clamp one end, rough turning the other end face and outer circle 220, (grinding amount), expanding the inner hole to 150, rough turning bearing hole 165*40, (grinding amount).Chamfering.

3, turn around, the other end of the clamp stretch length is less than 250, the end face of the car to the total length of 758, rough car outer circle 258 and 195 * 40, rough car inner hole 165 * 120 (grinding amount), chamfer, 4, clamp 220 * 70, the other end of the tailstock top, car outer circle 216, car outside the garden 222 * 124 (grinding amount), 5, drill 8 holes 9

6. Heat treatment, quenching and tempering treatment, for process stability, 7, clamp 222*124 end, grinding inner hole 165JS6*40, grinding outer garden 220h6

8, U-turn, with 165JS6 as the benchmark, fine turning 258*20,9, still based on 165JS6, grinding inner garden 165JS6*120 and outer garden 222H6*124,

The card is not necessary, say probably, the cutting 765Punch car from 150, length 758

All the dimensions of the outer circle of the top clamp car are completed at one time, 195 U-turn car four-jaw chuck, center frame, table alignment, all the inner holes of the car, (U-turn) The basic meaning should be clear, and the details will be considered again.

Haha, I just finished a craft card for a part. What other processing requirements do you have for this part, I haven't given it, I can't do it, besides, it takes a lot of time to do that, but it is estimated that no one has time to do it.