1. Grinding the outer circle

The outer circle of a workpiece is generally ground on a regular or universal cylindrical grinder. There are generally three types of cylindrical grinding: longitudinal grinding, transverse grinding, and deep grinding.

1.1 Longitudinal grinding method

When using the longitudinal grinding method to grind an outer circle, the high-speed rotation of the grinding wheel is the main motion, and the workpiece undergoes circular feed motion while also reciprocating longitudinally with the worktable, achieving axial feed along the workpiece. At the end of each single stroke or reciprocating stroke, the grinding wheel undergoes periodic lateral movement to achieve radial feed along the workpiece, gradually removing all remaining grinding allowance in the radial direction of the workpiece. After grinding to the size, perform a smooth grinding process without cross feed until the spark disappears. Due to the small radial feed amount, small grinding force, and good heat dissipation conditions of the longitudinal grinding method, the grinding accuracy and surface quality of the workpiece are fully improved, which can meet higher machining quality requirements, but the grinding efficiency is relatively low. The longitudinal grinding method is suitable for grinding larger workpieces and is a commonly used method for single piece and small batch production.

1.2 Horizontal grinding method

When using the transverse grinding method to grind the outer circle, the width of the grinding wheel is larger than the grinding width of the workpiece, and the workpiece does not need to undergo longitudinal (axial) feed motion. The grinding wheel continuously or intermittently moves along the transverse feed at a slow speed, achieving radial feed to the workpiece until the grinding meets the size requirements. Its characteristics are: fully utilizing the cutting ability of the grinding wheel, high grinding efficiency, and also suitable for forming grinding. However, during the grinding process, the contact area between the grinding wheel and the workpiece is large, which increases the grinding force and makes the workpiece prone to deformation and burns. In addition, the shape error of the grinding wheel directly affects the geometric accuracy of the workpiece, resulting in lower grinding accuracy and larger surface roughness values. Therefore, it is necessary to use a high-power and rigid grinding machine, and at the same time, sufficient cutting fluid must be provided to achieve the purpose of cooling during grinding. When using the transverse grinding method, it is required that the process system has good rigidity and the workpiece should be short rather than long. The precision grinding process of the short stepped shaft neck usually adopts this grinding method.

1.3 Deep grinding method

Deep grinding method is a relatively advanced method with high productivity, and the grinding allowance is generally 0.1-0.35mm. This method can grind the entire allowance in one go. When grinding, the feed rate is relatively small, usually taking a longitudinal feed rate of 1-2 mm/r, which is about 15% of the longitudinal grinding method, and the processing time is about 30-75% of the longitudinal grinding method.

2. Grinding end face

On a universal cylindrical grinder, the end face of the grinding wheel can be used to grind the shoulder surface and end plane of the workpiece. Before starting grinding, the end face of the grinding wheel should slowly approach the end face of the workpiece to be ground. During the grinding process, the axial feed of the workpiece should also be very small. This is because the rigidity of the grinding wheel end face is very poor, and it can basically not withstand large axial forces. Therefore, a good solution is to use the outer conical surface of the grinding wheel to grind the end face of the workpiece. At this time, the workbench should be pulled at a larger angle.

3. Grinding inner circle

The inner grinding tool of an external cylindrical grinder can grind the inner circle of a workpiece. When grinding the inner circle, most workpieces use the outer circle or end face as the positioning reference and are clamped on the chuck for grinding. When grinding the inner conical surface, only the inner circle grinding tool needs to be deflected by one circumferential angle.

Unlike outer circle grinding, the diameter of the grinding wheel in inner circle grinding is limited by the aperture of the workpiece and is generally smaller, so the grinding wheel wears quickly and needs to be repaired and replaced regularly. The grinding wheel used in inner circle grinding is softer than that used in outer circle grinding because the contact area between the grinding wheel and the workpiece is larger during inner circle grinding. In addition, the diameter of the grinding wheel shaft is relatively small, the overhanging length is large, and the rigidity is poor, so the grinding depth cannot be large, which reduces productivity.

Two processing tips for cylindrical grinding

The cylindrical grinder can demonstrate its advantages when traditional turning is not possible or difficult to perform. The processing of difficult to turn materials (such as hard metals) and workpieces with extremely high surface and size requirements belongs to the traditional application scope of grinding. If the workpiece needs to be clamped in one device to complete processing, the equipment needs to have good flexibility; The cylindrical grinder achieves internal and external grinding of medium-sized workpieces in one clamping process according to the usual division, which can simultaneously meet two types of grinding. At the same time, due to the wide range of processed products, good flexibility and many technical tricks are required.

The hydraulic system of the cylindrical grinder belongs to a closed loop pipeline, with hidden faults and difficult diagnosis as its main characteristics. The workbench is driven by hydraulic pressure oil to move the piston rod of the hydraulic cylinder longitudinally back and forth. When the workbench changes direction, any impact or significant retention is found, which will directly affect the dressing of the grinding wheel.

The external grinding machine can be adjusted by adjusting the screws on both sides of the control box. Generally, when there is an impact phenomenon, the screws can be screwed in. However, when there is a stagnation phenomenon, the opposite is true. When adjusting, it is necessary to pay attention to whether the adjusting screw is the end of the control phase adjustment, otherwise it will have the opposite effect and cause new problems. After the adjustment is ready, the screw should be re locked.

When there is still stagnation and impact after adjusting the cylindrical grinder, it is necessary to scrape and grind whether the contact surface between the workbench and the guide rail is vertical and parallel, and heat it with mechanical oil and stearic acid at about 150 ℃. After cooling, add the workbench guide rail.

2024 July 1st Week JFZ Product Recommendation:

Tapered Roller Bearing:

The inner and outer ring raceways are segments of cones and the rollers are tapered so that the conical surfaces of the raceways, and the roller axes, if projected, would all meet at a common point on the main axis of the bearing. This geometry makes the motion of the cones remain coaxial, with no sliding motion between the raceways and the outside diameter of the rollers.

This conical geometry creates a linear contact patch which permits greater loads to be carried than with spherical (ball) bearings, which have point contact. The geometry means that the tangential speeds of the surfaces of each of the rollers are the same as their raceways along the whole length of the contact patch and no differential scrubbing occurs.

The rollers are stabilized and restrained by a flange on the inner ring, against which their large end slides, which stops the rollers from popping out due to the "pumpkin seed effect" of their conical shape.

The larger the half angles of these cones the larger the axial force that the bearing can sustain.

Tapered roller bearings are separable into a cone assembly and a cup. The non-separable cone assembly consists of the inner ring, the rollers, and a cage that retains and evenly spaces the rollers. The cup is simply the outer ring. Internal clearance is established during mounting by the axial position of the cone relative to the cup, although preloaded installations without clearance are common.

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