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Cutting tool grinding cann’t ignore six issues

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Update time : 2017-12-21 16:17:55

First, the tool materialDue to the complexity of the tool application, the professional grinding center must be based on the failure of the tool being sharpened grinding dressing program in a timely manner, and track the use of the tool. A professional tool grinding center must also continue to sum up experience in order to repair the tool better, more special!Cutting tool in the tool common materials are: high-speed steel, powder metallurgy high-speed steel, carbide and PCD, CBN, metal ceramics and other superhard materials. High-speed steel cutting tools, toughness, carbide cutting tool hardness but poor toughness. The density of carbide cutting tools is significantly higher than the high-speed steel cutting tools. These two materials are the main material for drill bits, reamers, milling cutters and taps. Powder metallurgy high speed steel performance between the above two materials, mainly for the manufacture of rough cutters and taps.
High-speed steel cutting tool due to good material toughness, it is not sensitive to the collision. However, high hardness and toughness of carbide cutting tools, very sensitive to the collision, edge easy to jump. Therefore, in the grinding process, carbide tools must be placed on the operation and take great care to prevent the collision between tools or tools fall.
As the high-speed steel cutting tools are mostly relatively low precision, grinding requirements are not high, coupled with its price is not high, so many factories set up their own tool shop grinding. However, carbide cutting tools often need to be sent to a professional grinding center grinding. According to the statistics of some domestic tool sharpening centers, more than 80% of the repairing tools are cemented carbide tools.

Second, tool grinding machine
As the tool material is very hard, so generally can only use grinding to change its shape. Tool manufacturing, grinding common in the tool grinder are the following:
1. Grinder machine: grinding bits, end mills and other tools slot or back.
2. Polishing angle machine: grinding cone taper angle (or eccentric angle).
3. Repair transverse edge blade: the horizontal edge of the correction bit.
4. Manual universal tool grinder: grinding cylindrical, groove, back, top corner, horizontal edge, plane, rake and so on. Commonly used in a small number of complex shape tool.
5.CNC grinder: generally five-axis linkage, the function is determined by the software. Generally used for grinding a large number of high precision, but not complicated tools, such as drill bits, end mills, reamers and so on. The main suppliers of such grinders come from Germany, Switzerland, the United States, Australia and Japan

Third, the wheelAbrasive
Different materials of abrasive wheel suitable for grinding different materials of the tool. Different parts of the tool need to use abrasive grain size is also different, in order to ensure the best combination of edge protection and processing efficiency.
Alumina: used to grind HSS tools. Grinding wheel cheap, easy to correct into different shapes for grinding complex tools (Corundum).
Silicon Carbide: Used to correct CBN grinding wheel and diamond grinding wheel.
CBN (cubic boron carbide): for grinding HSS tool. High price, but durable.
Internationally, the wheel is represented by B, such as B107, where 107 represents the size of the abrasive grain
Diamond: for HM grinding tool, high price, but durable. D on the wheel to represent, such as D64, of which 64 represents the size of the abrasive particle diameter.
Shape
In order to facilitate the grinding of different parts of the tool, the wheel should have different shapes. The most commonly used are:
Parallel wheel (1A1): grinding angle, diameter, back and so on.
Disc grinding wheel (12V9,11V9): Grinding spiral groove, the main cutter, cutting edge, repair chisel, etc.
After a period of use of the wheel needs to be revised its shape (including the plane, angle and rounded R). Wheels must be frequently used to clean up the debris filled between the abrasive particles to improve the grinding capacity of the grinding wheel.

Fourth, grinding standardWhether to have a good set of tool sharpening standards is a measure of whether a sharpening center is a professional standard. Grinding standard, the general provisions of different tools in the cutting of different materials, the cutting edge of the technical parameters, including cutting edge angle, apex angle, rake angle, relief angle, chamfering, chamfering and so on parameters (in the carbide drill , The process of making the blade passivation is called "down-edge", the width of the down-edge is related to the material to be cut, generally between 0.03-0.25Mm. The process of chamfering on the edge (tip point) Each professional company has its own grinding standard that has been summarized for many years.
Difference between HM drill and HSS drill:
HSS drill bit: the apex angle is generally 118 degrees, sometimes greater than 130 degrees; sharp blade; precision (edge ​​height, symmetry, circumferential runout) requirements are relatively low. Chisel has a variety of repair methods.
HM drill: apex angle is generally 140 degrees; straight groove drill is often 130 degrees, three-edge drill is generally 150 degrees. Blade and tip (edge) is not sharp, often passivated, or the fall edge and chamfer; high precision. Chisel edge is often modified into S-shaped, in order to facilitate chip breaking.
After the corner:
The relief angle of the cutting edge is very important for the tool. After the angle is too large, blade easy to jump jump, easy to "tie knife"; angle is too small, the friction is too large, cutting adverse.
The clearance angle of the tool depends on the material being cut, the type of tool, and the diameter of the tool. In general, the relief angle decreases as the diameter of the tool increases. In addition, the material is hard to cut, the smaller corner, otherwise, large angle.

Five, tool testing equipmentTool detection equipment generally divided into three categories: knife tool, projector and universal tool measuring instrument. Tool setting tool is mainly used for tool setting (such as length) of CNC equipment such as machining center. It is also used to detect parameters such as angle, radius and step length. The function of projector is also used to detect parameters such as angle, radius and step length . However, these two generally can not measure the clearance angle of the tool. The universal tool measuring instrument can measure most of the geometric parameters of the tool, including the relief angle.
Therefore, the professional tool grinding center must be equipped with universal tool measuring instrument. However, there are not many suppliers for this equipment and there are German and French products on the market.

Six, grinding mechanics
The best equipment also requires personnel to operate, training grinding mechanics is of course one of the most critical aspects. As China's tool manufacturing industry is relatively backward, coupled with the serious lack of vocational and technical training, tool grinding mechanic training can only be solved by the enterprises themselves.