Brief Introduction of Engine Crankshaft Machining Technology

Starting from this article, the author combined his own work experience to open the topic "Common Parts and Their Processing Technology" to introduce common parts and their processing technology one after another.

The first part, the automotive powertrain product line, will include engine crankshafts, cylinder blocks and cylinder heads, as well as housing and valve body parts for its transmissions.

In the first chapter, the author introduces the most familiar engine crankshaft parts.

The function of the crankshaft

The crankshaft is the most important part in the engine. It bears the force from the connecting rod and converts it into torque, which is output through the crankshaft and drives other accessories on the engine to work.

 For example, the following picture shows the crankshaft and its "surrounding partners" in a four-stroke engine:

Type of crankshaft

 [Divided by material]

[Divided by the number of cylinders]

[According to the arrangement of cylinders]

crankshaft structure

First, let's look at the composition of the common crankshaft assembly, as shown in the following figure:

The common components of the crankshaft and their names are shown in the following figure:

Process design of crankshaft

The list of processes required for crankshafts of different materials is shown in the following figure:

The basic principle of crankshaft machining datum selection: select the machining datum according to the design basis.

Usually, the main journal at both ends is used as the radial reference, the thrust surface is used as the axial reference, and the P1 connecting rod journal is used as the angular reference.

Here, please note the codes of the crankshaft main journal and connecting rod journal. The main journal is MAIN JOURNAL, choose M as the code, and the connecting rod journal PIN JOURNAL, choose P as the code.

At the same time, taking the crankshaft of a four-stroke engine as an example, there are 5 main journals and 4 connecting rod journals on the crankshaft. We name the main journals and connecting rod journals closest to the mandrel end as M1 and P1, and the other main journals and connecting rod journals are respectively are M2\M3\M4\M5 and P2\P3\P4.

The principle of crankshaft processing technology: first roughing and then fine, first datum and then other, first face and then hole, first main surface and then secondary surface.

Process of steel crankshaft

Below, we select the crankshaft of a steel, in-line four-cylinder engine as an example to introduce the crankshaft processing technology.

First, let's take a look at the process description:

In the next article, the author will follow the above list to introduce common equipment, processing tools and common problems for you one by one. Welcome to subscribe and pay attention.