grinders and abrasive machining.

by:Gewinn     2020-06-06
Anatomy of the machine tool editor notes: the first part of this series, published on February 1993, has a covered machining center.
The second part, machine control, appears in June 1993.
The third part, published in May 1994, examined the lathe and lathe.
Grinding, as a method of shaping hard materials, is likely to be one of the most basic technologies in all technologies, and is likely to be a plunder of the metal processing itself.
There is evidence that a number of neo-globalists, together with the Egyptians and the builders of Stonehenge, for example, use sand as an abrasive to smooth the stone tools and building blocks they use.
We are still doing basically the same thing today, but on a more controllable and complex basis, when we finish hardened steel workpieces on CNC grinding machines.
Grinding is a chip.
When manufacturing a metal cutting process, each bit is as much as machining or milling, except that it is done at the \"micro\" level where the chip is too small to be easy
Another basic difference between grinding and It
Scale cousins is a grinding \"tool\" which is a grinding particle and is not a uniform shape and guide carrier whether it is a wheel, stone or other equipment.
While this discussion will focus on grinding deliberately with wheels --
Built-in metal processing machine tools, it is important to pay attention to, from grinding to cutting
Grinding on the platform, even grinding knives are basic grinding operations.
Grinding is also used in many places outside the industry for a variety of applications, from plastic telescope mirrors, to precision dimensional measurements and finishing of quartz crystals used for computer and communication equipment oscillators.
From the point of view of metal cutting, grinding is the product of the combination of turning and milling.
Just like milling, the grinding tool is also moving, just like turning, and the workpiece is almost always moving, although no rotation is required.
The difference between rotating the workpiece and the workpiece moving in a linear or oscillating way under the grinding tool, but in theory it is fixed, which defines the most basic division in the grinding application.
The former is usually described as \"cylindrical\" grinding, and the latter as \"surface\" grinding, although both types can produce precision surfaces on the workpiece that are not necessarily round or flat
In fact, tools and workpieces are usually moving, which makes the analysis and control of grinding operations much more complicated than turning or milling.
That\'s part of why grinding is one of the last major metal processing processes to transition from \"black art\" to science, by the way, many grinding machine manufacturers still tend to design and manufacture one of the main reasons for their own CNC controls.
Design basically many cylindrical grinding machines are placed on a pattern similar to the alathe.
Instead of having a tool holder, they have a mechanism for feeding the grinding wheel and its related machinery, but all the other elements, the main pin, the tail frame, the way, for those familiar with turning the machine, the bed is usually easy to identify.
However, the main difference is that the whole workpiece holding system is usually installed on a set of roads, so it can pass through the wheel during the grinding operation.
The cylindrical grinder is also designed as a \"Chuck\", which is very common in ID grinding applications.
In these machines, the wheels and their associated machinery are installed in the position where the tailstock is normally located, and the wheels feed along the axis of the rotation of the workpiece.
The ID grinder usually uses wheels with a smaller diameter and runs at a higher spindle speed than the OD machine.
Generally, in the OD cylindrical grinding machine, the shaft head is fed to the workpiece in the radial direction, and the workpiece can be kept stationary or reciprocating through the workpiece.
When the workpiece moves back and forth, the feed movement is usually only done at the end of each stroke.
Cut-in grinding is closer to the traditional single
The point turns conceptually because the wheel can go in and out to produce specific features on the workpiece, such as the shoulder.
The third major type of cylindrical grinding machine is the \"no center\" design with no direct simulation in the turning field.
In a centerless grinder, the workpiece is not supported by a center or Chuck, but is supported on the \"Blade\" between the grinding wheel and the \"adjusting\" wheel that controls its rotation.
\"Adjust\" the wheel to control the rotation speed of the workpiece as a driving mechanism, and as a brake if the workpiece speeds up from the grinding wheel.
The \"Blade\" keeps the work in place between the two wheels.
There are also several basic designs for Surface Grinding Machines.
The most common possibility is the wheel mounted on the machining table and its related machinery or other linear movement devices that hold the workpiece.
When the workpiece moves back and forth under it, the wheel passes through the reciprocating axis line.
Conceptually, this type of grinder is similar to a planing machine in which the tool holder is replaced by a grinding wheel and its associated machinery.
On this type of machine, grinding is usually done with the perimeter of the wheel.
The workpiece can also be attached to the rotating workbench, which rotates on the periphery or under the surface of the wheel for Surface Grinding.
When using a wheel face, this process is often called a disc Mill and can be either horizontal or vertical depending on the direction of rotation. Double-
A disc grinder, usually called a double
Disc grinder is the most effective machine to feed the workpiece between wheels on linear, rotating or oscillating fixing devices, which can produce flat parallel surfaces at high productivity.
The change in theme grinding is a process with such a wide range of applications that many changes have been developed over the years about these basic design topics and will not attempt to detail all of them here.
Ultra-precision grinding machine
The entire series of precision bearing ball mills and other professional grinding machines can easily be the subject of a longer article than this series.
However, these principles are basically universal and should apply to almost any grinding application you may have.
A professional grinding machine worth mentioning is a tool and tool grinding machine, as the name implies, it is designed for sharp and re-grinding
Sharp knives.
These machines are basically mixed and contain the features of the cylindrical and planar grinding machines that are necessary for the special tasks they need to perform. A sub-
The specialty of tool grinder is a series of machines specially designed for redesign
Sharpened twist drill.
They are naturally called drill grinding machines.
The selection criteria for tool grinding machines depend on the limited application value of the general guide, which is not discussed here.
Regardless of the type of grinder, the most important attribute it must have is rigidity and stability.
This is especially true in creepfeed applications, which is a special form of grinding, which is carried out in one channel, with very high cutting depth and low working speed.
Properly applied, creep feed grinding can reduce the overall processing time by 50% without loss of size or geometric accuracy or surface finish.
However, to achieve these results, a grinder must be specifically designed for creep feed applications, since the technology is particularly sensitive to the static and dynamic stability of the machine, and the requirement is three times higher than the spindle power of the conventional grinding process.
Creep feed also requires special trimming capability, careful attention to wheel \"hardness\", good coolant control, and extensive experience
Based on process knowledge.
As with all other metal processing techniques, creep feed provides a significant advantage for specific applications when applied correctly.
It\'s not universal medicine, and it\'s not the answer to every grinding question.
Given its rather professional nature, you are advised to deal with the process with a healthy and prudent attitude before investing in your money to make sure it is the right answer to your needs.
Just like turning the machine, there is really no secret about the structural design of the grinder.
It\'s easier for you to see stability-
Damping properties such as polymer or concrete
The filling base in the grinder is much more than the filling base in the lathe or machining center, however, in general, the structural selection you will see will be familiar and relatively easy to sort out.
In fact, for the hardness, on the grinding side of the equation, you may have more options than on the structure.
In addition to choosing granularity, keys, and shapes as you always have, you will soon make more basic choices between traditional materials such as sic, alumina, and cubic bn (CBN)
It has rapidly expanded its application in the grinding of black metal materials.
Although CBN has been used for grinding hardened steel for some time, recent developments in bonding and other manufacturing techniques have greatly broadened the use of this very hard wear material.
Coincidentally, as a material for turn-milling tools, CBN also promotes so-
Called \"hard turn\" operation.
Therefore, with the grinding application of the CBNturning and milling tools to take away the \"hard\" end of the spectrum, the CBN wheels are adding them on the \"soft\" end.
For example, the CBN wheels are rapidly becoming high-
Production applications such as automotive cams and crankshaft grinding, which provide superior performance and longevity when applied correctly.
This is necessary because the cost of the CBN wheel is several orders of magnitude higher than the traditional wheel of the same size, although it is still lower than the diamond.
The extra money you get is a wheel which is much faster and has a long life thanks to hardness and heat
Resistance of CBN abrasive. In a high-
Batch applications like the engine factory, due to the reduction of wheel wear, extended life of size control and simultaneous improvement, make the CBN a very attractive option.
Unfortunately, since the application parameters are very different, you can\'t usually replace the traditional CBN wheel with a CBN wheel.
Unless your grinder is used to handle the CBN, it may not, and the price of the wheel makes it a very expensive experiment.
This is a very noteworthy technology, because with the improvement of manufacturing methods and
Bulk customers require cost reduction.
Whether the performance advantage of the CBN is any good for you depends on what kind of grinding application you have, of course, but the wheel has a longer life and better size control, for most of us, higher productivity is a very attractive solution.
In fact, this suggests that it may be wise to include the ability to handle the CBN on the new grinder purchased in the next few years, as long as the cost of including this ability is reasonable.
At the very least, it can be placed on the table when you renegotiate the next grinder.
What does that mean, of course, is the bearing and the drive--
There are two major areas of technological change and major controversy in the grinding industry today.
The argument for the bearing is that the mechanical and fluid static forces and ultimately may be magnetic.
The argument on the mechanical side is mature, mature technology, and
Understand operational features, simplicity, and (sometimes)lower cost.
For this reason, the school answers with infinite life (
\"Oil does not wear \")
Good dynamic stiffness and low maintenance (
\"Oil does not wear \"), and (sometimes)lower cost. Who\'s right?
Most likely they are.
Often, the right answer depends more on what you want a machine to do than on the performance of the components.
If you want to grind a \"bazillion\" same widget on the same machine every year for the next decade, you may be advised to actively look at the spindle with a static hydraulic bearing-
There may also be static hydraulic methods and ballscrews.
On the other hand, if you are properly maintained, you may also be satisfied with the mechanical bearing machine ---
After all, they have been around for a long time.
The debate about driving is not a debate, it\'s more a post-
There is no guarantee to move to the direct person.
Drive the servo spindle.
It doesn\'t make sense to beat a dead horse, so saying that the future is electronic means that everything is enough for the servo.
The Dresser is another major component needed for almost every grinding operation.
The Dresser has two purposes.
First, in order to make the wheels real, the cutting surface rotates concentric with the shaft.
Second, remove glaze and other
When restoring any necessary special shape or geometry, make conditional adjustments to the cutting surface.
While simple grinding machines are often trimmed with grinding rods or hardened steel cutters, more sophisticated machines use some sort of mechanical finishing system.
Options include single
Diamond tools, sometimes under CNC control
Inlaid steel tools, rotating Diamond wheels, steel wheels for \"extrusion forming\", and even traditional grinding wheels commonly used to trim Diamond and CBN wheels.
Each dressing method has the advantages of being suitable for a specific range of grinding applications, so the selection does depend on the application.
From experience, choose the most flexible dress option, which will generate acceptable productivity in your main application. CNC or manual?
This is a simple option when you are evaluating a turn or milling machine, and the grinder also has many of the same considerations, but usually for very different reasons.
For example, consider the nature of the process.
One of the main advantages of CNC in a milling machine or lathe is the ability to easily program the complex movement of the tool to produce the same surface features on the workpiece.
In the grinder, all you have to do is assemble the required functions into the wheel and automatically transfer to the workpiece.
This is relatively easy for a higher volume form dresser or a single form
Point diamond vanity and low Templatevolumework.
While I will be the first to acknowledge that the actual procedure is not as simple as it just came up, it does illustrate that.
So why are you paying a higher price for CNCgrinder?
The answer is for control, but not necessarily for direct control of the features of the workpiece when milling or turning.
The advantage of CNC in grinding is that it allows you to control the machining process, which directly affects the size, geometry and finish of the workpiece.
Perhaps it would be better to illustrate this with a rather complex example.
Traditionally, the cam angle of the car is ground during the insertion process
The type operation of wheel feed is controlled by a cam synchronized with the rotation of the workpiece.
While this arrangement is able to meet historically acceptable standards of size, finish and flap geometry while providing sufficient productivity, it has become increasingly unable to meet the stricter quality requirements of today\'s higher power
Density engines with acceptable productivity.
One answer is to convert the process to CNC control.
In The Machine, the spindle, the wheel-
Both the feed and the work head are servo.
CNC control drive.
This means in practice that by changing the wheel and/or the speed of the workpiece, the grinding conditions can be adjusted to achieve the most effective conditions for grinding this precise point. Where the cam-
The CNC machine requires almost no type grinder, and it is bound to include a series of compromises in its operation.
The result is a more effective, accurate and effective process through micro-
Manage operations.
This is a good example of why a grinder manufacturer is more likely to design and manufacture its own CNC than a lathe or milling machine manufacturer.
These controls must be very fast and powerful, and must be dealt with that normally does not exist in the non-
Grinder bed.
The CNC Grinding machine can also handle the CNC trimmer, which can increase the size control and wheel life when integrated into an integrated control system.
CNC dresser, essentially a small diamond
A tool lathe that makes the wheels of cylindrical or flat grinding easy to implement and produces simple or complex profiles for shape grinding.
Of course, CNC also makes it easier to control relatively simple workpiece properties like size, in which case the latest generation of in-
The process meter works in conjunction with the control to keep the dimensions and Geometry at tolerances that can only be achieved in the laboratory a few years ago.
Finally, it may be easier to set up a CNC grinder-
Short term use-
Run the application.
However, given everything, its main advantage is that it provides precise control over the process itself. What\'s next?
The trend of grinding technology is clearly towards greater size and geometric accuracy, higher productivity and more complex control capabilities.
Drive the development of the first two technologies, such as today\'s CBNwheels and continuous improvement of bearings and motors.
Driving this growth is the widespread growth of equally complex digital electronics products, which has changed the face of manufacturing around the world.
An example is amachine, which is able to maintain tolerances measured in nanometers (one-
1 m billionaire)
Tough mode grinding in case of hard, non-hard
Metal workpieces used in the electronics industry, such as glass and certain crystals.
It is also capable of grinding irregular, non-
Circular profiles similar to tolerances.
This machine uses advanced CBN wheels.
The chemical process of trimming and wheel cleaning.
While one might want to know the practical use of such a machine today, I remember some time when it was said that grinding tech demonstrators were able to maintain dimensional tolerances in inches per million.
Today, 50 million is common among engine manufacturers around the world, not too strict tolerances.
Is 50 nm impossible in the next century?
Don\'t bet it.
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