Common tool materials in tool grinding are: high speed steel, powder metallurgy high speed steel, hard alloy and PCD, CBN, cermet and other superhard materials. High speed steel tool sharp, good toughness; Carbide cutting tools have high hardness but poor toughness. The density of carbide tool is obviously higher than that of HSS tool. These two materials are the main materials of drill bit, reamer, milling cutter and tap. Powder metallurgy high speed steel has properties between the above two materials and is mainly used in the manufacture of coarse milling cutter and tap.
HSS cutters are not sensitive to impact because of their good toughness. But hard alloy tool hardness is high and brittle, very sensitive to collision, the edge is easy to jump. Therefore, in the process of grinding, the operation and placement of cemented carbide tools must be very careful to prevent the collision between the tools or tool fall.
Because the precision of high speed steel tool is mostly relatively low, its grinding requirements are not high, plus its price is not high, so, many manufacturers buy tool grinding machine set up tool shop for its grinding.
Because the tool material is very hard, so, generally can only use grinding to change its shape. There are several common tool grinding machines in the manufacturing and grinding of tools:
1). Groove grinding machine: grinding the groove or back of the drill bit, end milling cutter and other tools.
2). Top Angle grinder: grinding the cone top Angle (or eccentric lip relief angle) of the drill bit.
3). Transverse edge repairing machine: correct the transverse edge of the drill bit.
4). Manual universal tool grinder: grinding the outer circle, groove, back, top Angle, transverse edge, plane, front cutter surface, etc. It is often used for cutting tools with small quantity and complicated shape.
5).CNC grinding machine: generally five axis linkage, the function is determined by the software. Generally used for grinding large number, high precision requirements, but not complex tools, such as drill, end milling cutter, reamer.
3, grinding wheel
1). The abrasive
Grinding wheel particles of different materials are suitable for grinding tools of different materials. Different parts of the tool need to use different abrasive size, to ensure the best combination of edge protection and processing efficiency.
Alumina: used for grinding HSS cutter. Grinding wheel is cheap, easy to correct into different shapes for the repair and grinding of complex tools.
Silicon carbide: used for correcting CBN and diamond grinding wheels.
CBN (cubic boron carbide) : used for grinding HSS tools. Expensive, but durable.
Diamond: used for HM tool grinding, high price, but durable. The grinding wheel is represented by D, such as D64, where 64 represents the size of grinding particle diameter.
In order to facilitate the grinding of different parts of the cutter, the grinding wheel should have different shapes. The most commonly used are:
Parallel grinding wheel (1A1) : grinding top Angle, outside diameter, back, etc.
Disc wheel (12V9,11V9) : grinding spiral groove, milling cutter’s main and secondary cutting edge, repair transverse edge, etc
The grinding wheel needs to be modified after a period of use (including plane, Angle and circular Angle R). The grinding wheel must often be cleaned with a cleaning stone to remove the cuttings between the grinding particles to improve the grinding ability of the wheel.
4, grinding standards
Whether there is a set of good tool grinding standards is to measure whether a professional grinding standards. In the standard of repairing and grinding, the technical parameters of cutting edge of different cutting tools when cutting different materials are generally stipulated, including blade inclination angle, top angle, front angle, lip relief angle, chamfering edge and other parameters.
5, Tool detection equipment
Tool detection equipment is generally divided into three categories: tool instrument, projector and universal tool measurement instrument. Tool is mainly used for machining center and other CNC equipment tool preparation (such as length, etc.), but also used to detect Angle, radius, ladder length and other parameters; The function of the projector is also used to detect the angle, radius, step length and other parameters. However, the above two generally can not measure the tool lip relief angle. Universal tool measuring instrument can measure most geometric parameters of the tool, including the lip relief angle.