Grinding shafts or, in principle, grinding operation is a workpiece processing procedure, which consists in the use of a cutting tool made of abrasive material. The surface after this treatment is a collection of micro-traces. They are left abrasive grains available on the tool. The surface of the finished product is characterized by minimal roughness.
Description of grinding device
Shafts are ground using a grinding wheel. This circle is a porous body, consisting of a large number of abrasive grains. These grains are held together by a bunch. In addition, pores are located between these grains and ligaments. Grains themselves are made of very durable material, and their number reaches tens or even hundreds of thousands.
As for the working profile of the wheel for grinding shafts, it consists of cutting edges of grains of abrasive type. They are located at different distances from the surface. In addition, the grinding process is a procedure during which chips are removed. Due to the fact that large quantities of chips are removed, this leads not only to grinding of the material, but also to significant heat generation in the contact zone. For this reason, this operation is carried out only in the presence of a constant supply of a large number of cutting lubricants.
General types of grinding
To date, there are three main types of grinding of shafts - it is thin, preliminary, fair. When using the preliminary type of grinding, it is possible to achieve an accuracy of 8-9 in terms of quality. As for the second important factor - roughness, it is from 0.4 to 6.3 microns. Grinding of finishing shafts is possible only after the workpiece has undergone heat treatment. This procedure allows you to increase the accuracy to 6-7 in terms of quality and reduce the roughness to 0.2-3.2 microns. The most accurate method is fine grinding, which allows you to achieve a roughness of 0.025-0.1 microns. The process is also divided into two types - it is round and centerless.
Grinding round type
The machine for grinding the necks of the crankshaft or for any other products of round and cylindrical type is performed on circular grinding machines. In this case, the workpiece will be mounted in the center, in the chuck or collet of the device. To date, there are two main types of circular grinding - a longitudinal feed and a plunge method.
As for the first type, this is a procedure that is performed using reciprocating movements. In this case, the part moves relative to the grinding wheel.
Grinding by cutting is carried out by a circle, the width of which should be greater than the length of the area that needs to be processed. In this case, the circle will have a feed only of the transverse type. If you use a shaped wheel, you can process several parts at the same time. Since this method is more productive than with longitudinal feed, it is used much more often in large-scale and mass production.
Centerless grinding
This operation is carried out on centerless grinding machines . In this case, longitudinal feed and plunge methods are also used.
As for the operation with longitudinal feed, it is used for processing smooth shafts. The insertion procedure is used for machining shafts having a shoulder. In this way, you can process parts that are characterized by a conical surface. For this, a leading circle tucked onto a cone is usually used.
It is worth adding that when using the cutting method, the circle gradually loses its shape and cutting ability. Quite often, this is called greasing the circle. In order to return the circle to its original state and thereby return its operational characteristics to the previous level, the editing procedure is used. This procedure is carried out with diamonds in frames, diamond pencils, etc. The editing process itself does not affect grinding, but if it is carried out poorly, the characteristics of the wheel will deteriorate, which means that it will be worse to carry out the operation.
Machine tools for crankshaft
Today, a good solution would be to use the AMC-SCHOU crankshaft grinding machine.
This equipment is made of heavy-duty castings. The device has a hydraulic circle feed, as well as locking pins. A distinctive feature of the device is a fairly quick regulation of the feed circle, which is carried out without a reverse reaction.
The main procedure that is required when repairing the crankshaft is grinding. This operation allows you to fix the geometry of the device, fix chips, increase engine life, and also reduce the risk of new problems.
Grinding the crankshaft journals now eliminates scuffing and wear. By itself, the grinding process of this device is an option that requires the presence of special machine equipment, as well as high specialist skills.
Steering wheel grinding
Grinding the steering shaft is also a fairly common operation. Experts recommend using it only if rust is on the surface type fixture. In addition, the maximum diameter reduction is allowed no more than 0.1 mm. In the event that the corrosion is deemed to be deep, grinding of the part by 0.5 mm is allowed, no more. If grinding is done independently, it is very important that the working area of the shaft is perfectly sanded. Most often, with manual processing, sandpaper is used for this . Typically, processing begins when using very coarse P80 paper. Further, the graininess decreases, and for the final processing the smallest sandpaper is used at all.
Factory work
As for grinding the steering rack shaft in the workshop or in production, a special machine is used for this, which must be controlled by an experienced turner. It is important to know that during operation it is necessary to constantly control the deviation of the form. It should go in accordance with regulatory documents. Before starting repairs, it is necessary to conduct a visual inspection of the part to conclude the advisability of grinding the shaft.
To date, a fairly important aspect of the procedure has become its cost. It depends on factors such as the type of stock, the amount of work, and the thickness of the corroded layer. The main advantage of grinding the power shafts of rails in the workshops was that they have stands for checking the performance of the product. If there are any shortcomings, then there is the possibility of their immediate elimination.