In the actual production, PURROS Machinery has collected mass customers’ problems about grinding drill bits by hand (manual grinding drill bits), now, list the summary of the problems and how to solve as bellow for your reference and study. In the actual production, PURROS Machinery has collected mass customers’ problems about grinding drill bits by hand (manual grinding drill bits), now, list the summary of the problems and how to solve as bellow for your reference and study.
Step 1: Checking the point angle (cutting lip angle) of standard twist drill bit is correct or not, and whether it is symmetric with the axis of the standard twist drill bit? (The correct point angle of standard twist drill bit is ±118°, if it be used to drill harder materials that the point angle can be extended to 120°; if there are the softer materials, the point angle should smaller than before, but keep mind, do not smaller than 90°.)
Step 2: To check the length and height of two major cutting lip (major cutting edge) are consistent. Because the quality of the machined holes are affected by whether the length is the same.
The check method for step 1 and step 2 is that: Place the cutting part of twist drill bit keeps in a vertical position, keep eyesight at the horizontal level, and then repeatedly rotate 180°, where is the center axis of standard twist drill bit, to observe whether the length of two major cutting lips are same in rotation. It is an assumption that to observe the length of two major cutting lips at the center of axis; If the lengths of two major cutting lips are different, that the shorter side should be grinded.Continue reading
Drill bits come in a wide range of shapes and sizes, and are available in a variety of materials and coatings. Most tooling and machining operations have a drill bit that’s designed specifically for the task. Here’s a quick overview of several types of drill bits, materials and design types.
Drill bits are the special rotating tools that have cutting capacity at the top. Generally, drill bits are made from carbon steel (SK), HHS (SKH2, SKH3), etc, and then by milling machining or quenching after rolling, the final step is the grinding after tempering heat treatment. Drill bits are used for machining metals or other materials. Drill bits have a wide useful, such as drilling machine, lathe machine, milling machine and power drill, etc.
First: Preparation Before Grinding
A: Assembly of Drill Bit and Fixture
- Checking the diameter of drill bit shank, then select the suitable collet chuck and cutting sets.
- Insert the collet chuck into the fixture and lock the nut.
- Put the drill bit into the collet chuck, and keep 35~50mm out of the collet chuck.
- Adjust the scale to suit the outer diameter of the drill bit, and adjust the angle of point angle.
Attention: Keep some margin for adjusting before locking the chuck sets.
Definition of Ni Zhifu Ordinary Twist Drill Bit: Based on standard twist drill that the cutting part is grinded onto a special shaped drill bit. The standard twist drill consist of two major cutting lips (major cutting edges) and a chisel edge. The most fatal weakness is that the negative front angle of chisel edge and dead center are larger, led to the cutting conditions are unfavorable. Ni Zhifu Ordinary Twist Drill Bit is that grinding two symmetrical crescent grooves based on standard twist drill, forming arc blade, and then sharpening two inner straight edges on the chisel edge and dead center. After that, with the chisel edge and original two straight edges, making the standard twist drill into “Three knife-points and seven knife-edges” that is the Ni Zhifu Ordinary Twist Drill Bit.Continue reading
In actual work, we will encounter some special machining phenomenon, such as machining a larger diameter hole, or bottom of hole should beflat. Today, here we introduce reaming and countersinking, let’s go.
Carpenter Drill Bit: The carpenter drill bit for drilling wood there has larger amount of stock removal. Generally, it is made of ordinary carbon steel, the manufacturing process of the carpenter drill is simple, such as forging, stamping, grinding, etc.
Metal Drill Bit: Generally, the metal drill bit is made of alloy of hardness or HHS(high-speed steel), etc. The metal drill bit is cast and molded, after that to be grinded by grinding wheel on the grinding machine. Its manufacturing process is more complicated than carpenter drill bit.
The drilling machining is one of the most difficult machiningin metal machining, cause of that:
1th: Holesmachiningare the forming machining, the design of drill bit is good or not that directlyeffects on the accuracyof bore diameter.
2nd: The blade is in the hole, cooling is difficult.Continue reading