■-、 Tool material
Common tool materials in tool grinding are: high speed steel (HSS), powder metallurgy high speed steel (PM-HSS), cemented carbide (HM), PCD, CBN and other hard materials.
material. High-speed steel tools are sharp and have good toughness, while cemented carbide tools have high hardness but poor toughness. The density of cemented carbide tools is greater than that of high-speed steel tools. These two materials
It is the main material for drills, reamers, milling cutters and taps. The performance of powder metallurgy high-speed steel is between the above two materials, and it is mainly used to manufacture rough milling cutters and taps.
High-speed steel cutting tools are not sensitive to collision due to their good toughness. However, cemented carbide tools have high hardness and brittleness, are sensitive to collision, and the cutting edge is easy to jump. So, after grinding
During the process, the operation and placement of cemented carbide tools should be careful to prevent collisions between the tools or the tools from falling.
■Two, tool grinder
Because the tool material is hard, generally only grinding can be used to change its shape. Common tool grinders in the manufacture and grinding of tools include the following:
●1. Groove grinding machine: Grinds the groove or back of tools such as drills and end mills.
●2. Top angle grinding machine: Grinds the cone apex angle of the drill bit.
●3. Chisel edge trimming machine: Correct the chisel edge of the drill.
●4. Manual universal tool grinder: grinding external circle, groove, back, top angle, chisel edge, plane, rake face, etc. It is often used for tools with a small number of complex shapes.
●5. Five-axis CNC grinder: The function is determined by the software. -Generally used for grinding tools with large quantity, high precision requirements, but not complicated, such as drills, end mills, etc.
■Three, grinding wheel
1. Abrasive particles
Grinding wheels of different materials are suitable for grinding tools of different materials. Different parts of the tool need to use different sizes of abrasive grains to ensure the protection and reinforcement of the cutting edge.
Combination of work efficiency.
Alumina: used to grind HSS tools. The grinding wheel is cheap and easy to modify into different shapes for grinding complex tools.
Silicon carbide: used to modify CBN grinding wheels and diamond grinding wheels.
CBN (cubic boron carbide): used for grinding HSS tools. High price, but easy to use. , Grinding wheel is represented by B, such as B107, where 107 represents the size of the abrasive grain diameter.
Diamond: Used to grind HM tools, high price, but easy to use. The grinding wheel is represented by D, such as D64, where 64 represents the size of the abrasive grain diameter.
2. Shape
In order to facilitate the grinding of different parts of the tool, the grinding wheel should have different shapes. Commonly used ones are:
-Parallel grinding wheel (1A1): grinding the top angle, outer diameter, back, etc.
-Dish-shaped grinding wheels (12V9, 11V9): Grinding spiral grooves, main and minor cutting edges of milling cutters, chisel edges, etc.
After a period of use of the grinding wheel, its shape (including plane, angle and rounded corner R) needs to be corrected. Grinding wheels need to often use cleaning stones to fill the cuts between the abrasive grains.
The chips are removed to increase the grinding ability of the grinding wheel.
■Four, tool parameters
1. Name definition
Here is an agreement: in cemented carbide drills, the process of dulling the blade is called "inverted edge". The width of the inverted edge is related to the material to be cut.
Between 0.03-0.25mm. The process of chamfering on the edge (tip point) is called "chamfering".
In an end mill, the edge on the circumferential surface is the main cutting edge. On the end face, the upper edge is the secondary cutting edge.
2. The difference between HM bit and HSS bit
HSS drill bit: the top angle is generally 118 degrees, sometimes greater than 130 degrees; the blade is sharp; the accuracy (blade height difference, symmetry, circumferential runout) is required
Relatively low. There are many ways to repair chisel.
HM drill bit: the top angle is generally 140 degrees; the straight flute drill is often 130 degrees, and the three-edged drill is generally 150 degrees. The blade and the tip (on the edge) are not sharp,
It is often passivated, or called chamfering and chamfering; it requires high precision.
Chisel blades are often repaired into an S shape to facilitate chip breaking.
■Fifth, the principle of grinding
1. Correct selection of grinding wheels (type and model).
2. For the newly arrived tool, first measure the main geometric parameters and record and archive, and record the degree of tool wear and the situation to be corrected.
3. Input the wheel data first, and then input the tool data.
4. After grinding, measure the main parameters of the tool and compare it with the grinding standard before correcting it.
