Creep feed grinding process how to grind creep feed

Creep feed grinding is a kind of strong grinding, also known as deep creep feed grinding or creep grinding. The grinding workpiece can be ground to the required size and shape accuracy after one or several strokes. Creep feed grinding is suitable for grinding the surfaces and grooves of high hardness and high toughness materials, such as heat-resistant alloy steel, stainless steel, high-speed steel, etc. Now let's introduce the creep feed grinding process in detail.

Creep feed grinding process
1. The grinding depth is large. The contact arc length between the grinding wheel and the workpiece is long, and the metal removal rate is high. Rough grinding and fine grinding are completed in one process, and the production efficiency is 3-5 times higher than that of ordinary grinding.
2. The wear of grinding wheel is small. Because the feed speed is very low, the thickness of debris is thin, and the grinding force borne by a single abrasive is small, the abrasive is not easy to wear, break and fall off; Secondly, the number of reciprocating strokes of the workbench is less, the feed is slow, and the number of collisions between the grinding wheel and the workpiece is less, which reduces the impact between the grinding wheel and the edge of the workpiece, so that the grinding wheel can maintain accuracy for a long time.
3. Due to the small grinding force borne by a single abrasive, the grinding accuracy is high and the surface roughness is low. At the same time, due to the good shape retention of the grinding wheel, the machining accuracy is relatively stable. In addition, the contact arc length can attenuate the grinding vibration, reduce the chatter, reduce the surface waviness and surface stress of the workpiece, and it is not easy to produce grinding cracks.

4. Good economic benefits. Because of the large cutting depth, the grinding is hardly affected by the defects on the workpiece surface, such as oxide skin, white layer of castings, etc. the blanks of precision casting or precision forging can be directly ground to form, reducing machining procedures, reducing blank machining allowance and man hours, shortening production cycle and reducing production costs.
5. The equipment cost is high. The creep feed grinder must increase the power and rigidity of the grinder, and has a creep feed and speed change system, automatic grinding wheel dressing and automatic compensation devices, as well as a strong cooling system. Therefore, the grinder has complex structure, high accuracy requirements, and the equipment cost is much higher than that of ordinary grinders.
6. The large contact surface increases the grinding heat, and the contact arc length makes it difficult for the grinding fluid to enter the grinding area, and the workpiece surface is easy to burn, so a strong cooling system should be equipped.

2、 Requirements of creep feed grinding for machine tools
1. Grinding power: creep feed grinding is efficient grinding, which is mostly used for form grinding. Therefore, the power of the wheel drive motor is required to be large enough, generally more than 18kw.
2. Feeding movement of workbench: when the workbench is slowly fed, it is required to be stable without crawling at the feeding speed of 20mm/min. Generally, hydraulic transmission is not adopted, but mechanical transmission is adopted. At present, screw pairs or ball screw pairs are mostly used to ensure that the machine tool has high transmission stiffness. There should also be stepless speed regulation and quick return mechanism.
3. Rigidity of machine tool: the rigidity of process system is one of the reasons for workpiece processing error. Creep feed grinding requires high dynamic and static stiffness of machine tools. In order to improve the static stiffness of the system, the double-layer reinforced wall structure can be used on the main components such as the front and rear bed, column and carriage; Increase the diameter of the main shaft; The side guide surface of the grinding head vertical movement guide rail and the column carriage horizontal movement adopts the preloaded roller guide rail structure to eliminate the guide rail gap and improve the contact stiffness.
4. Spindle system accuracy: due to the high power of creep feed grinding spindle and form grinding, the spindle is required to be rigid, and axial or radial movement is not allowed.

5. Cooling and flushing: there are two special problems in creep feed grinding: one is that the grinding debris is thin and long, which is easy to block and adhere to the surface of the grinding wheel; Second, the grinding force borne by a single abrasive grain is small, and the self sharpening of the grinding wheel is poor, which is easy to burn the surface of the workpiece. Therefore, it is required to strengthen the cooling and flushing effect of grinding fluid.
In order to ensure the cooling and flushing effect, the grinding fluid should be kept clean, and the grinding fluid tank must have a reliable filtration system.
The cooling effect is also related to the grinding direction. The cooling condition is good during the forward grinding, the grinding fluid can be brought into the grinding area smoothly, and the cooling effect is good; During reverse grinding, the grinding fluid is not easy to enter the grinding area, and the cooling effect is poor. In addition, during forward grinding, the threshing of the grinding wheel can only fall on the ground surface, which will not scratch the machined surface when washed away by the grinding fluid.