The metal grinding process is a process that relies on cutting and plastic deformation of the material surface to remove the convex parts on the surface of the workpiece to obtain a smooth surface. Grinding is widely used and is one of the main methods for precision processing of machine parts. For the plane process with high precision requirements and the plane process of quenched parts, grinding method is generally used. When flat grinding, for simple ferromagnetic materials, electromagnetic chucks can be used to clamp the workpiece; for complex-shaped or non-ferromagnetic materials, precision flat-mouth vise or special clamps can be used to clamp the workpiece first, and then electromagnetic chucks or vacuum chucks can be used to secure the workpiece. Workpiece stability.

Common problems and solutions in metal grinding process:

1. Common problems in grinding process

(1) Grinding process accuracy problem

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Accuracy is mainly formed by the combination of machine tool accuracy, fixture accuracy and the above-mentioned grinding process parameters. The accuracy and stability of the grinding wheel's swing range when grinding the seat surface will affect the straightness of the seat surface busbar. Therefore, the reasonable determination of the CNC machine tool grinding coordinates and the position of the grinding wheel correction coordinates are also important parameters for improving the quality of the workpiece.

(2) Grinding process burn problem

Grinding burn will occur when the process parameters are unreasonable or the dimensional accuracy of the blank is not well controlled during the grinding process. This kind of grinding The main factors causing burns include low linear speed of the grinding wheel, low cutting force, and large normal force on the surface of the grinding wheel and workpiece.

(3) Grinding process crack problem

When the selection of grinding parameters is unreasonable, the grinding wheel is not in good correction status, single-point grinding occurs, or there is residual stress after heat treatment of the part. After grinding, the grinding surface of the middle hole seat surface will produce cracks or fine cracks. Cracks and fine cracks, especially in the seat pressure chamber, will cause cavitation on the edge of the seat surface, which will reduce the fatigue strength of the workpiece. When working for a period of time, It will expire early after a certain period of time.

(4) Grinding process lubrication issues

Grinding oil mainly plays the functions of lubrication, cooling, cleaning, etc. Sometimes, because the performance of the grinding oil used does not meet the process requirements, At high speeds, the process surface cannot be covered, and oxide films and hardened layers will be produced, making the workpiece hardness uneven. This is especially the case when grinding the seat surface of the fuel injection nozzle. As a result, the wear resistance, corrosion resistance and fatigue strength of the workpiece are greatly reduced, and the service life of the oil nozzle is shortened.

2. Technical scheme of the grinding process

(1) Clamping method of the grinding process

When grinding, the large outer circle after correcting the accuracy is used And process angle positioning, the single film chuck clamps the large outer circle, so that the positioning and clamping method can avoid the axial grinding of the middle hole seat surface.

(2) Cutting allowance in the grinding process

Cutting allowance is an important parameter to ensure efficient and high-precision compound grinding. Usually the fine grinding allowance is controlled at the micron level , taking into account factors such as runout during clamping.

(3) Selection method of grinding wheel

Modern grinding technology all adopts high-speed grinding, the selection of grinding wheel and abrasive, the proportion of binder, and the sintering pores of the grinding wheel Repeated tests are required to ensure that the grinding chips will not stick to the grinding wheel during the grinding process and maintain good self-sharpening properties.

(4) The rotation speed of the grinding workpiece

The rotation speed of the workpiece is related to the diameter of the grinding surface. The rotation speed of the workpiece will have a greater impact on the grinding marks and surface roughness. The impact is that too low a rotational speed will cause ripples on the grinding surface and increase surface residual stress, and too high a rotational speed will cause burns on the grinding surface.

(5) Power speed of the grinding spindle

The linear speed of the grinding wheel is a very important factor in the grinding process. The current direction of grinding development is that the linear speed of the grinding wheel continues to increase. . High-speed grinding mainly has the advantages of small deformation of the workpiece, long life of the grinding wheel, and high quality.

(6) Feed speed of the grinding spindle

The transverse feed swing speed and longitudinal cutting speed should be coordinated with the test. If the transverse swing speed is too fast, the grinding wheel cutting rate requirement is high and it is easy to cause Squeeze the grinding wheel to ensure the taper of the grinding hole.

3. Development of special grinding oil

(1) Extreme pressure performance of grinding oil

Special grinding oil contains sulfide extreme pressure anti-wear properties Additive components can effectively protect the grinding tools and improve process accuracy.

(2) Chemical properties of grinding oil

Compared with rapeseed oil, machine oil and recycled oil, special grinding oil has good chemical stability and will not Harmful to equipment, human body, and environment.

(3) Other properties of grinding oil

Special grinding oil has passed strict tests in terms of viscosity, flash point, pour point, thermal conductivity, etc. to meet the needs of various industries. process requirements.