Technical Column

5 new technologies for CNC machining of engine metal parts

5 new technologies for CNC machining of engine metal parts5 new technologies for CNC machining of engine metal parts

The engine is the heart of the car. 4C parts such as cylinder blocks, cylinder heads, crankshafts are core components. Their quality directly affects the performance of the engine. In the manufacture of 4C parts, the cost of chip accumulation in the chamber, machining deformation and post-treatment of cutting fluid has always been the most difficult problem in the manufacture of key engine parts. It limits the improvement of product delivery quality and the reduction of product manufacturing costs. Through the implementation of the project, we have researched and applied new technologies such as grinding technology, flexible cleaning technology, simulated cylinder head technology, MQL technology, cluster layout, etc. to effectively solve these problems.

Reverse grinding technology

That is, the grindstone spindle is perpendicular to the bottom surface, the workpiece is placed vertically in the machine tool, and the two grindstone spindles drive two CBN grindstones to grind vertically from both sides of the workpiece. conduct.

Inverted grinding technology has three advantages in machining shafts:

  • 1. The workpiece is in the vertical state during machining. The gravity of the work that hinders machining in horizontal machining is converted into a useful top tightening force, avoiding deformation of the product due to the gravity of the work, and improving the ability to guarantee the accuracy of camshaft grinding.
  • 2. Double grinding spindles are symmetrically distributed along the axis of the workpiece. In the double grinding spindle method, the radial force of the workpiece is balanced by canceling the directional force, and the vertical grinding force is balanced by the central frame, thus the force of the cam shaft during grinding. Balance is achieved. Eliminates product deformation due to grinding force during camshaft machining.
  • 3. CBN’s efficient grinding technology doubles efficiency. A high-strength, long-life CBN grindstone is used for grinding, and two CBN grindstones operate simultaneously during grinding, greatly improving grinding efficiency.

Flexible cleaning process

The flexible cleaning process expands the application of machining centers and revolutionizes the perfect combination of high pressure cleaning and machining. This process takes full advantage of the flexibility of the machining center and the high pressure characteristics of the machining center’s internal cooling system. By optimizing the structure of the tool’s internal cooling holes in the machining center, high-pressure internal cooling cutting fluid for cooling the spindle and tool is sprayed from the machine tool spindle. High-pressure internal cold water of up to 5MPa collides with the treatment part, which exerts a good auxiliary tip breaking effect. After cnc machining, use a special tool for fixed-point high-pressure cleaning to perform high-pressure deburring again. The linkage characteristics of the machining center are used to flexibly clean parts that cannot be effectively cleaned with a cleaner.

There are four main advantages to the flexible cleaning process for machine tools.

High cleaning pressure.

The injection force of pressure washer is proportional to the nozzle outlet pressure. The cold pressure inside a machine tool is 5 MPa, and that of a traditional pressure vacuum cleaner is 1.5 MPa. Under the same other conditions, the water injection force of the cold hole of the tool is 2.12 times greater than that of the washing machine. Cleaning the inserts with a stream of water in the cold holes of the machine tool improves cleaning quality.

Good orientation.

The diameter of the cold hole of the tool is Φ1.5mm and the diameter of the hole is small, which is advantageous for improving the cleaning speed and the direction of the water column, and it is not easy to scatter.

High flexibility.

Machining centers can achieve 5-axis linkage, can achieve multi-angle, dead-angle cleaning, and can effectively solve the problem of specially shaped surface debris.

low cost

The cleaning time and processing time are the same, which greatly improves the utilization of the equipment.

Simulated cylinder head technology

In the engine assembly, after the assembly of the cylinder block and the cylinder head is completed, the cylinder bore is deformed by receiving the pressing force from the cylinder head, and the friction between the cylinder bore and the piston increases. It affects the performance and life of the engine. Before the cylinder is completed, the cured simulated cylinder head can be assembled and then the cylinder holes can be finished and superfinished, thereby reducing the deformation of the cylinder bore after assembly of the entire machine. This technique for assembling a simulated cylinder head is an analog cylinder head technique. The cylinder assembly is simulated after the cylinder head is completed, the deformation caused by the assembly of the cylinder block and the cylinder head is considered in advance, and the quality of the assembled product is effectively guaranteed. Tables 1 and 2 show the analysis results of deformation data when assembling the simulated cylinder head and the product cylinder head.

The deformation tendency after assembling the simulated cylinder head through the analysis and comparison of the deformation after assembling the actual cylinder head and the simulated cylinder head is the same as that when assembling the actual cylinder head, and the difference in deformation is the same. You can see that it is small. Pseudo-cylinder heads can be used in place of actual cylinder heads for finishing and super-finishing cylinder holes.

When assembling the simulated cylinder head, the cylinder bore is machined to the parameter requirements required for product performance, and the cylinder bore is deformed after the simulated cylinder head is removed. However, after the assembly line is assembled to the actual cylinder head, the cylinder hole returns to the stressed state when the cylinder head is tightened, so that the accuracy after assembly is ensured.

MQL technology

MQL technology, or gas-liquid mixing micro-lubrication technology, is a new type of cutting lubrication technology. Mix the appropriate amount of MQL oil with compressed air and spray it through the cold holes in the tool onto the machined surface to cool, lubricate, and clean the insert. Currently, this technology is fully applied in the field of crankshaft machining and has been validated and applied to the machining of cylinders and cylinder heads.
As an environmentally friendly semi-dry processing technology, MQL technology has three advantages:

  • 1. MQL oil does not need to be changed during processing, it only needs to be added regularly, no wastewater is discharged and oil mist is discharged directly after refining by the device. Effectively avoid environmental pollution caused by industrial production.
  • 2. Improve tool cutting conditions, reduce and reduce cutting heat generated during machining, and improve tool life.
  • 3. A small amount of MQL oil replaces the cutting fluid, reducing excipient consumption and cutting fluid post-treatment costs.