Surface grinding are special machines used to clean the surface of products from unnecessary layers. Most often, this type of equipment is used to process wooden workpieces. However, a surface grinding machine for metal is also a fairly common type of aggregate. They are used to process parts made of steel, aluminum, copper, etc.
A bit of history
The surface grinding machine was invented in 1874 in America. Initially, it used circles cut from whole pieces of various kinds of abrasive rocks as a working tool. Since they had to be changed frequently, such units at that time did not receive much distribution. However, already in 1893, after the invention of artificial abrasives, surface grinding machines became very popular and popular.
What are they used for?
This type of equipment is used for:
The main feature of these machines is that they are designed specifically for the finishing of parts with a flat surface. To fine-tune the shape of the workpiece they are not used.
Operating principle
The operation of this type of equipment is based on a very simple principle. The turning of the workpiece is carried out by means of an abrasive wheel rotating at a high speed . The latter is driven by an electric motor. In this case, processing can be carried out both by the surface of the circle and by its end face. Today on sale there are also machines of this type with two circles, characterized by very high productivity.
In most cases, a surface grinding machine operates as follows:
An electric motor rotates a gear pump, which pumps oil into the channels of the hydraulic system.
The latter, once in the gearbox, approaches the starting crane.
When the crane is turned on, oil flows into the cylinder for supplying the part and moves the piston, and at the same time the table fastened with it.
At the end of its stroke, the table turns the switch tap, which is responsible for directing oil to one side or another of the spool of the feed cylinder.
The direction of the oil current in this case reverses and the table begins to move after it.
Design features
Grinding machines of this type are usually characterized by increased strength, since the parts processed on them in most cases have significant weight. The maximum allowable weight of the workpiece is 600 kg, and the height is 280 mm.
The column of this type of machine is mounted on a pedestal cast integrally with the bed. In its middle part, it has a recess, on both sides of which there are guides. The carriage moves along the latter. Horizontal guides designed for a spindle head are fixed on it.
The workpiece in such machines is mounted either directly on the table, or using special magnetic clamps. Sometimes, mechanical devices are also used to fix the part.
The table surface grinding machine can be round or rectangular. Depending on this, the method of supplying the part is selected: longitudinal or circular. Sometimes equipment of this type is used to process parts of a very large area. In this case, a transverse feed technique is used. The surface of the table surface grinding machine is equipped with a special fluoroplastic coating. This ensures a smooth movement and wear resistance.
The spindle of a surface grinding machine can be positioned in different ways. On this basis, the equipment is divided into vertical and horizontal. Each of these groups has both its advantages and disadvantages.
Like any other, surface grinding machines are indicated by conventional serial numbers. It is impossible to determine the functionality of the equipment by such an inscription. To do this, you need to study the passport of a surface grinding machine.
End grinding
There are several types of similar processing of parts:
Multipass In this case, the workpiece is installed on the work surface and moves at a speed of the order of 45 m / s. In this case, the part moves several times under the circle, and the latter is gradually fed to a depth until a layer of metal or wood of the required thickness is removed.
Single pass. This technique is used on round table machines. In this case, the tool is fed to the entire depth vertically in one pass.
Double sided. On such equipment, both ends of the workpiece are simultaneously processed simultaneously.
Peripheral grinding
This method is used to process parts made of not too hard materials. Peripheral grinding is:
Deep. In this case, a very large layer of material is removed for each treatment cycle.
With mortise feed. This technique is used to process those workpieces for which the height is greater than the width.
With intermittent feed. This technology allows for the highest quality grinding of even very large workpieces.
Grinding wheels
These tools can be made in the form of a washer or cylinder. They consist of grains of various kinds of abrasive materials of high stiffness, bonded together by a ceramic, volcanic or bakelite binder. Grinding wheels can have different sizes and profiles. They are selected depending on the brand of the machine and the type of parts processed on it.
Optional equipment
Very often, equipment such as a cooling unit is connected to a surface grinding machine. It is necessary in order to reduce the temperature of the working bodies of the machine during the processing of parts. This can significantly extend their service life.
Also, in machines of this type, such additional equipment as the feeding and receiving roller table, speed inverters, various kinds of units for cleaning the coolant, etc. can be used.
Specifications
Machines of this type can vary in power, productivity and functionality. Schemes of surface grinding machines are presented on this page. Technical characteristics of this type of equipment may be different. Next, we will see what parameters such machines can have on the example of the very popular 3G71 model. This unit is intended only for peripheral grinding of workpieces. Its design includes a bed, a column with a headstock, a desktop and a hydraulic system.
From the table below you can find out what kind of surface grinding this machine has technical characteristics.
Parameter | Value |
Minimum workpiece height / width / length | 320/200/630 mm |
Maximum weight of the workpiece | 100 kg |
Maximum distance from spindle axis to table | 80 mm |
Table sizes | 630x200 mm |
Table movement longitudinal / transverse | 70-710 / 235 mm |
Range of speeds of longitudinal movement | 5-20 m / min |
Automatic cross feed speed | 0.7 m / min |
Grinding wheel dimensions | 250x25x75 mm |
Circle speed | 3740 rpm |
Machine Dimensions | 1870x1550x1980 mm |
Machine weight | 1900 kg |
Despite the fact that the 3G71 surface grinding machine was developed back in the USSR, it is still used in production and is considered quite productive and reliable. On its basis, more advanced and expensive 3G71M machines were designed.