What Is Tool Grinding Machinery?
Tool grinding machinery is used to regrind cutting tools that have lost their sharpness after a certain amount of cutting.
Tool grinding machinery is also called a grinder. In this case, cutting tools include drills, end mills, milling cutters, and hob cutters.
There are various types of grinders depending on the type of tool grinding machinery, each of which is used in a specialized machine-like manner. Specifically, they include drill grinders, cutter grinders, and hob grinders. There are also universal tool grinding machines that can grind many types of tools. By equipping them with a variety of auxiliary equipment, they can be used for a wide range of tools.
Uses of Tool Grinding Machinery
Tool grinding machinery is used for regrinding cutting tools. Tools to be ground with tool grinding machinery are used to machine metal and are called cutting tools.
Universal tool grinding machinery, which allows for general-purpose use, may not be able to regrind end mills and other tools with complex shapes. In addition, they generally require manual grinding, which requires skill.
On the other hand, with the advent of CNC tool grinding machinery, which now controls multiple axes through numerical control, along with technological innovation, it is possible to perform automatic grinding of tools with complex shapes. Appropriate search conditions and grinding wheel selection ensure stable grinding. By freely rotating the grinding wheel axis, a variety of tools can be ground in a single clamping for a high quality finish.
Principle of Tool Grinding Machinery
Tool grinding machinery is used to grind the surface of a tool that has lost its sharpness by placing the tool gradually against a grinding wheel rotating at high speed. These processes make it possible to regain sharpness.
Tools with common shapes, such as end mills, milling cutters, reamers, and taps, can be ground quickly with universal tool grinding machinery because they do not require complex program setups and can be ground manually. However, for grinding a large number of tools with complex geometries in a stable manner, CNC tool grinding machinery has the advantage.
Universal tool grinding machinery requires skill because two or three axes must be operated manually and simultaneously. There are also simplified NC tool grinding machinery that simplifies the grinding process by using NC control for only one axis. When only the main axis is NC-controlled, grinding can be performed without the need for skilled operators, such as the spiral shape of the clearance and rake surfaces of the outer circumference of an end mill or the spiral shape of the rake and clearance surfaces of a ball end mill R.
Types of Tool Grinding Machinery
The following three types of tool grinding machinery are typical types.
1. Universal Tool Grinding Machinery
Universal tool grinding machinery is used for grinding common drills and end mills. Universal tool grinding machinery has a number of adjustment axes that allow the structure and shape of the tool to be ground to be adjusted to various shapes, diameters, lengths, and cutting edge conditions. However, knowledge of the tool to be searched for is required. In addition, skill is required to operate the numerous adjustment axes properly.
2. CNC Tool Grinding Machinery
Today, CNC tool grinding machinery, which has a metal method that can move multiple axes simultaneously or in conjunction with each other, is the most commonly used for machining common tools. Some of these newer CNC tool grinding machinery have functions to measure the shape of the ground tool and to adjust the machining allowance by detecting deformation of the grinding wheel due to machining heat.
3. Special-Purpose Grinding Machines
Dedicated grinding machines are available for hobs and pinion cutters used for machining gears with special shapes, and for broaches used for machining key grooves, spline grooves, etc.
Other Information on Tool Grinding Machinery
1. The Difference Between Grinding and Polishing or Cutting Processes
Grinding and polishing processes are the same in that they are performed to regenerate the sharpness of a tool, but the methods of regeneration are different. In grinding, abrasive grains are used to shave the tool blade and change the shape itself, while in polishing, abrasive grains are used to apply pressure to the tool blade in order to polish the surface smooth.
Cutting is often performed not with abrasive grains, but with reamers, end mills, and other tools with the purpose of cutting away the shape of the workpiece, which is then fine-tuned by grinding or polishing.
2. Grinding Wheels for Tool Grinding Machinery
Cutting tools are made of materials that are harder than ordinary steel, such as high-speed tool steel and cemented carbide. In addition, heat treatment and surface treatment are applied to increase the hardness of the material.
On the other hand, since the accuracy of cutting tool edge dimensions greatly affects the accuracy of finished dimensions during machining, grinding wheels coated with diamond or CBN (Carbon Boron Nitride) are used to grind high-precision, high-hardness work materials. During the grinding process, the heat generated during machining affects the dimensions of the grinding wheel or diamond wheel and the tool being ground, which in turn greatly affects the finished dimensions of the tool.
Although some recent CNC tool grinding machinery uses those heats to compensate for the dimensions, it is essential to use a grinding fluid that controls the temperature rise and controls the temperature because it affects the hardness and material composition of the tool being ground. The selection of the grinding fluid, as well as the tool grinding machinery, is important.