Tag Archives: sharpening machines

Analysis of the influence of the helix angle of the drill bit on the service life of the drill bit

Helix Angle is the angle between the helix line on the helical groove and the bit axis after it expands into a straight line. Since the lead of each point on helical groove was the same, the helical angle was different at different diameters of the drill bit, with the maximum helical angle at the outer diameter, and the smaller the helical angle was the closer to the center. Increasing the helix angle will increase the front angle, which is conducive to chip removal, but the rigidity of the drill will decrease. Standard twist drill helix angle is 18 ° ~ 38 °. For bits with smaller diameter, the helix angle should be smaller to ensure the rigidity of the drill bit.

According to the shape of twist drill, the helix angle of each point on the cutting edge is variable, and helix angle directly affects the front angle of the main cutting edge. The larger the helix angle is, the sharper the cutting edge will be and the lighter the cutting will be, otherwise it will cause severe machining hardening and wear the blade quickly. According to the cutting tool design data, helix angle of 30 ° can satisfy the use requirement, at the same time, it can be mass production.

PURROS there are many sharpening machines. If your tools wear a little bit, you can use our tool grinder. Before you buy a new tool, you can use a grinded tool for a period of time to save manufacturing costs.

What are the differences between normal wear and abnormal wear of cutting tools?

Tools in the production process will encounter a variety of problems, the master of mechanical processing often asked, “why can’t I use this cutter for so little time?”

Under the condition of high temperature, the tool will be gradually worn and damaged by the chip friction of the workpiece. But how can we distinguish the normal wear from the abnormal wear?

 

Normal wear and tear

 

Normal wear refers to the wear pattern that gradually expands with the increase of wear over time. There are two aspects that are clearly indicated as normal wear.

  1. Front wear: there is crescent depression wear at the front edge of the blade, which is formed by friction and high-temperature and high-pressure action during chip outflow.
  2. Main rear wear: the main rear wear is divided into three areas. It is assumed that blade tip wear C zone, and wear loss VC is caused by low strength and concentrated temperature near the blade tip. In the intermediate wear area B, except for uniform wear amount VB, the maximum wear amount in the severe wear area is VBmax, which is caused by friction and heat dissipation difference. The boundary wear N zone, where the cutting edge and the surface to be processed wear VN, is caused by high temperature oxidation and surface hardening.

 

Abnormal wear

 

Abnormal wear is usually caused by tool damage caused by impact, uneven heating and improper use during cutting.

  1. Crushing: small crushing on the cutting edge is caused by low cutting edge strength, impact and hard points in cutting layer.
  2. Cutting edge: it is easy to crack at the cutting point or cutting point, with brittle cutting material, low cutting strength and heavy cutting load.
  3. Thermal cracking: small cracks in the vertical cutting edge are caused by uneven cutting temperature, discontinuous cutting and uneven pouring of cutting fluid.
  4. Collapse: in the process of cutting, the cutting edge lost its cutting performance under the action of high temperature and high pressure, resulting in the collapse of the front or tip and cutting edge.

PURROS there are many sharpening machines. If your tools wear a little bit, you can use our tool grinder. Before you buy a new tool, you can use a grinded tool for a period of time to save manufacturing costs.

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