In mechanical manufacturing, metal cutting workload accounts for approximately 80%. Reasonable selection of tool materials for various workpiece materials, including tool geometry angle, cutting three elements, accurate installation of tools, and proficiency in tool grinding skills, is of great significance for improving processing quality, production efficiency, reducing consumption, and improving enterprise economic benefits. In production, there is a lack of necessary cutting knowledge and sharpening skills, especially theoretical knowledge and proficient sharpening skills for drill bits. Many drill bits, due to difficulties in sharpening, are afraid of affecting product quality after sharpening. By comparing and gradually improving cutting knowledge in production practice, one can master the skills of sharpening and using cutting tools.

1、 Tool material selection:

When cutting workpieces of different materials, it is necessary to choose different material cutting tools, which is of great significance for improving cutting efficiency and ensuring the quality of the processed workpiece.

The commonly used tool materials can be divided into two categories: hard alloy tools and high-speed steel tools. And hard alloy cutting tools are divided into three grades based on their cutting of different materials: YT (also known as tungsten cobalt titanium class), YG (also known as tungsten cobalt class), and YW (also known as universal blade).

2、 Selection of parameters such as tool rake angle, rake angle, and blade inclination angle:

Cutting different shapes and materials requires selecting appropriate parameters such as rake angle, rake angle, and blade inclination angle. Reasonable tool angle parameters are of great significance for improving machining quality, production efficiency, and reducing production costs. The conventional method is to cut ordinary steel components such as 45 #, 50 #, etc., usually with a front angle of ① 8-10 ° and a rear angle of ② 8 °, and a blade inclination angle of ③ 5-6 °.

Cutting castings: front angle ① 8 °, back angle ② 6 °, blade inclination angle ③ 3-5 °, cutting quenched and tempered steel, with a relative reduction of about 2 ° between the back angle and front angle. The blade inclination angle can be omitted or ground to a negative blade inclination angle of 2-3 ° to enhance the strength of the blade tip.

Intermittent cutting of workpieces has impacts. Generally, the front and rear angles and blade inclination angles used for machining quenched and tempered steel are used. The cutting hardness of workpieces ranges from HRC48 to 55. On the front cutting surface, the main cutting edge is ground to a negative chamfer of 3 ° and 1.5mm wide to facilitate impact resistance and increase the strength of the tool.

When cutting materials with high toughness and plasticity, such as A3, 20 # steel, copper, and other workpieces, large front angles and large blade angles are generally used. The front angle ① is 30-35 °, the blade angle ② is 25-35 °, and the back angle ③ is 15-20 °, or even larger.

3、 Selection of three cutting elements:

The cutting depth and cutting speed (workpiece or tool rotation) are often referred to as the three cutting factors. Reasonable selection of the three cutting factors is of great significance for improving production efficiency, tool service life, and product quality. The principle for selecting the three cutting elements is: first, select the cutting depth. Under the conditions of machine rigidity, tool bearing capacity, and other conditions, cut most of the machining allowance in rough machining as much as possible in order to improve production efficiency. Secondly, select the feed quantity, which is also an effective way to improve production efficiency.

Finally, the selection of cutting speed is closely related to improving the service life of cutting tools. The cutting speed must meet the bearing capacity of various tool materials, such as hardness alloy blades with a maximum cutting speed of 30-100m/min, and high-speed steel material tools with a cutting speed capacity of 18-30m/min. If the cutting speed exceeds this range, the tool usage will be affected, reducing the tool lifespan. For example, if the speed of the 8 drill bit is 2000r/min and the material of the 8 drill bit is steel, can it be used normally. According to the instruction, if the maximum cutting speed of the steel is ≤ 30m/min, then π dn/1000=3.14 * 8 * 2000/1000=50.24m/min> 30m/min. After calculation, at a speed of 2000r/min, the cutting speed of the 8 drill bit exceeded the maximum cutting speed of high-speed steel by 30m/min.

4、 Tool installation adjustment

Accurate installation of cutting tools is a skill that machine tool operators must understand and master proficiently. When the cutting tool is installed on the tool holder, the tip of the tool must be aligned with the center of the workpiece to ensure cutting accuracy. The various angles designed for the cutting tool (front angle, back angle, edge inclination angle, offset angle, etc.) work, and the tool can cut normally. If the tool tip is higher or lower than the center of the workpiece during installation, the front and back angles of the tool change. When the tool tip is higher than the center, the front angle increases and the back angle decreases. When the tool tip is lower than the center of the workpiece, the front angle decreases and the back angle increases. Both of these situations are not conducive to the normal cutting of the tool. For the forming tool, the workpiece processed above or below the center will have a thinner or fatter shape, which can be clearly observed in gear machining. Here is an example: a machine processing factory processes cylinder heads, and the slot cutting tool is installed on the boring row. Due to the installation hole of the tool being lower than the center of the workpiece, it quickly wears and burns during cutting the slot. After multiple adjustments to the machine tool, it has no effect, resulting in a temporary shutdown. When I went to the site for research, I saw that the phenomenon of tool burning was basically understood. I increased the back angle of the burned tool appropriately, from 6 ° to 12 °; After several years of use, it has been proven that the tool can be used normally without any adverse situations. Why can this matter be resolved quickly? This demonstrates the importance of mastering the accurate installation of the tool. I hope that young workers must master the accurate method of installing cutting tools when installing them.