Black oxide DIN 1.7734 5 Chromium Molybdenum Steel CNC machined auto part

Black oxide DIN 1.7734 5 Chromium Molybdenum Steel CNC machined auto parts

What is DIN 1.7734 5 Chromium Molybdenum Steel?

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Chrome-molybdenum steel, also known as medium temperature hydrogen resistant steel, is an alloy of chromium (Cr), molybdenum (Mo) and iron (Fe), carbon (C). Good quenching, can be deep quenching, rather than the surface quenching of anti-saw lock on the market, because of its special high quality performance, is often used to manufacture some high temperature and high pressure resistant valves and pressure vessels, such as chromium molybdenum steel safety valve, chromium molybdenum steel gate valve, screwdriver tool head, bicycle, etc.

Advantages of DIN 1.7734 5 Chromium Molybdenum Steel

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1. Good to machining
2. Good absorption of impact
3. Easy welding

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custom automotive parts for British partner

black oxide DIN 1.7734 5 Chromium Molybdenum Steel auto part

tolerance +/-0.012 mm

A new process to solve the problem of eccentric hole processing

1.7734 5 Chromium Molybdenum Steel auto part

low volume steel parts
For conventional turning processing, when the workpiece has eccentric hole or eccentric structure, it is necessary to design special fixture, multiple clamping to complete the turning process. If the precision of the workpiece is high, this method will cause a high rejection rate, and even make the turning process is not feasible. If the multi-axis turning center processing, through programming, scientific use of different rotating center axis and each power seat, the workpiece machining accuracy can be guaranteed reliably.

The eccentric workpiece is the part of the outer circle and the outer circle or the outer circle and the axis of the inner hole parallel but not coincide, partial a distance of the workpiece. The distance between these two parallel axes is called the eccentricity. The eccentric parts of the outer circle and the outer circle are called eccentric shaft or eccentric disc; The outer circle and inner hole eccentric parts called eccentric sleeve. As shown in the picture.

eccentric hole processing
In mechanical transmission, rotary motion becomes reciprocating linear motion or reciprocating linear motion becomes rotary motion, which is generally accomplished by using eccentric parts. For example, the lubricating pump driven by the eccentric workpiece in the headstock of the lathe, the crankshaft in the automobile engine, etc.

Eccentric shafts and eccentric sleeves are generally processed on lathes. Their processing principles are basically the same; the main thing is to take measures in clamping, that is, to find the axis of the eccentric part to be processed to coincide with the rotation axis of the main shaft of the lathe. Generally, there are five methods for turning eccentric workpieces, namely, eccentric workpieces are turned on a three-jaw chuck, eccentric workpieces are turned on a four-jaw chuck, eccentric workpieces are turned between two centers, eccentric workpieces are turned on eccentric chucks, and eccentric workpieces are turned on an eccentric chuck. Eccentric workpiece on the fixture.

Process analysis of traditional car eccentric parts

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1. Clamping with three-jaw chuck

(1) Turning method

Eccentric workpieces with short lengths can be turned on a three-jaw chuck. First turn the outer circle of the non-eccentric part of the eccentric workpiece, then place a gasket with a pre-selected thickness between any jaw of the chuck and the joint surface of the workpiece, calibrate the busbar and eccentric distance, and put Once the workpiece is clamped, it can be turned.


The thickness of the gasket can be calculated by an approximate formula; the thickness of the gasket is X=1.5e (eccentricity). If the calculation is more accurate, the eccentricity correction value k needs to be brought into the approximate formula to calculate and adjust the thickness of the gasket, then the approximate formula is: gasket thickness x=1.5e+k


△e=e-e measurement

In the formula: e—eccentricity of workpiece;

k—correction value of eccentricity, positive and negative are determined according to the actual measurement results;

△e—Measured eccentricity error after trial cutting;

e test—After the test cut, measure the eccentric distance.

(2) Measurement and inspection of eccentric workpieces

1.7734 5 Chromium Molybdenum Steel auto prototypes


When adjusting the side busbar and eccentricity of the workpiece, it is mainly carried out on the lathe with a dial indicator with a magnetic gauge seat (as shown in the right figure (c) below), and turning can be carried out until the requirements are met. After the workpiece is turned, in order to determine whether the eccentricity meets the requirements, a final inspection is required. The method is to put the workpiece into the V-type iron, measure it at the eccentric circle with a dial indicator, slowly rotate the workpiece, and observe its runout.

eccentric hole processing prototype

2. Use four-jaw single-action chuck for clamping

The correct steps are:

①. Install the marked workpiece on the four-jaw chuck. When clamping, first adjust the two claws of the chuck to make them in an asymmetrical position, the other two claws are in a symmetrical position, and the eccentric circle line of the workpiece is in the center of the chuck (see the right in the above picture)

②. Put a small flat plate and a scribing plate on the bed, and align the needle tip with the eccentric circle line to correct the eccentric circle. Then align the needle tip with the horizontal line of the outer circle, as shown on the left of the following figure, check whether the horizontal line is level from left to right. Rotate the workpiece 90°, check the other horizontal line in the same way, then tighten the clamp and recheck the workpiece clamping.

③ After the workpiece is calibrated, tighten the four claws again to start cutting. In the initial cutting, the feed rate should be small, the cutting depth should be shallow, and the cutting amount can be appropriately increased after the workpiece is rounded, otherwise the turning tool will be damaged or the workpiece will be displaced. As shown below (c) left:

eccentric hole processing steel part
The above two methods are relatively common processing methods, but both have disadvantages. Clamping is more troublesome, not easy to align, and prone to errors. And not suitable for mass production. In view of the above shortcomings, I designed an eccentric jig specially designed for mass production. And put into production, to achieve a certain effect.

3. Design of New Special Eccentric Fixture

The eccentric wheel fixture is mainly used for mass production of eccentric parts, and the parts diagram of the fixture is attached below (as shown in Figure 1).

When clamping, calibrate the inner hole of Ф60 to ensure the tolerance of the shape and position of the part. The clamping method is to clamp the workpiece at the left end of the fixture, which is corrected by the dial indicator, and the right end is clamped on the three-jaw self-centering chuck.


4.Use the eccentric wheel fixture to process the eccentric wheel, the following is the part drawing and processing technology card of the eccentric wheel.

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