Discussion on the processing method of the hottest

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Discussion on processing methods of parts with special shapes

for parts with the shape of parts or similar shapes as shown in Figure 1, the two ends are in the shape of stepped cylinders or domes, the middle is a regular hexagonal prism, and the center is a stepped hollow cylinder, and the diameter of the cylinders at both ends of the hexagon is close to the distance between the opposite sides of the hexagon. Preliminary analysis of its processing methods mainly include the following:

(1) mechanical cutting: that is, turning and drilling

(2) cold extrusion processing: no cutting processing

(3) extrusion plus cutting: that is, extrude to a certain shape before cutting, which can reduce the difficulty of extrusion die design and manufacturing, especially the difficulty of section a

Figure 1 special shape parts

the following describes the process and characteristics of each processing method as follows:

1 mechanical cutting

using the method of mechanical cutting, first select the raw materials (such as hexagonal steel), and then process according to the following process:

turning the large diameter outer circle f; Minor diameter outer circle E; Drill hole D; Cut off; Re clamp the U-turn car a; Center hole drilling; Pre drilling; Drill and ream hole B; Drill and ream hole C

the above processing technology is applicable to processing on an ordinary lathe. Each part requires about 15 minutes of processing time. If you use a six axis automatic lathe for processing, you can process one piece in 20 ~ 30 seconds. The process of each station is as follows:

(1) rough turning the outer circle F and a to the size; Drill hole B exceeds 1/2 of the hole depth

(2) rough turning path E; Drill hole B to the specified size

(3) finish turning outer circle f to size; Drill hole C exceeds 1/3 of the hole depth

(4) knurled (model) drill hole C exceeds 2/3 of the hole depth

(5) fine turning small diameter e, undercut; Drill hole C to size

(6) cut off

2 cold extrusion processing

cold extrusion is one of the advanced processes in metal pressure processing. It has the following advantages in recent years:

(1) saving raw materials. Cold extrusion is a plastic processing technology, which makes the metal volume plastic transfer without destroying the properties of the metal, so as to form the metal with less cutting and no cutting. In this way, a large number of metal scraps formed during cutting are avoided, and a large amount of steel and various metal materials are saved

(2) improve labor productivity. Cold extrusion is produced on the press, which is easy to operate, easy to master and high productivity

(3) parts with complex shapes can be machined

(4) cold extruded parts have high strength and rigidity

(5) ideal surface finish and dimensional accuracy can be obtained for cold extruded parts

as shown in Figure 1, the cold extrusion process of parts is:

blanking and upsetting; Annealing; Pre punching; Squeeze six sides; Positive and negative extrusion, large hole forming; Backward extrusion; Small hole punching

if there is a 500 ton press, the above second to sixth processes can be completed continuously on the same equipment. If there is no 500 ton press, it can also be completed by using a 30 to 100 ton punch

process deformation diagram is as follows:

Figure 2 process deformation diagram

3 process comparison

3.1 the total demand for plastic pipes will continue to increase, and the material utilization rate of mechanical processing is 26.48% (hexagonal steel)

the material utilization rate of cold extrusion is 98.25%

the material utilization rate of cold extrusion is 3.71 times that of mechanical processing

3.2 processing time

machining: if the belt of six axle automatic lathe is too deformed, the processing time of the bed is 30 seconds; 15 minutes for a single ordinary lathe

stamping: 2 ~ 3 seconds for 500 ton press with automatic feeding; The total processing time of a single punch is 18 seconds

4 analysis of key processes

from the previous cold extrusion processes, it seems that it is not too difficult, but once you start to do it, you will find that the hexagonal extrusion process is relatively difficult. The main problem is that the opposite edge distance between a and hexagonal is too close to s, only about 1mm. This structure will inevitably lead to the die jacket wall thickness is too thin, which is easy to cause die cracking. Facts have proved that the same is true. In the trial production stage, it is found that the pressing sleeve cracks when punching several workpieces. So how can we solve this contradiction? After careful analysis, research and testing, the solutions are as follows:

First: use better materials to make the pressure sleeve. First, better spring steel can be used. In addition, some relatively new materials, such as 65Nb, can be used to improve the service life of the mold

second: solve from the mold manufacturing process. As shown in Figure 3, during the processing of the movable pressing sleeve, molybdenum wire is used to cut it in advance, so that the cracking problem of the pressing sleeve can be well solved

Figure 3 mold manufacturing process diagram

third: when designing the hexagonal process, extrude the front a into hexagonal, and then process a on the lathe after extrusion. In this way, the mold design is much simpler, the structural strength of the mold is greatly improved, and the service life of the mold is greatly extended

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