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Composition of twist drill

The shank is the clamping part of the drill for centering and power transmission; The neck is used for withdrawing the grinding wheel when grinding the drill bit, and the specification and trademark of the drill bit are generally engraved on the neck; The working part of twist drill plays the role of cutting and guiding. The twist drill is a tool for drilling the round hole of the workpiece through its rotary cutting relative to the fixed axis. It is named because its chip holding groove is spiral and looks like a twist.

Twist drill is the most commonly used hole processing tool. The linear main cutting edge of this kind of drill is longer, the two main cutting edges are connected by the horizontal edge, and the chip holding groove is spiral (convenient for chip removal).

A part of the spiral groove constitutes the rake face, and the rake face and top angle determine the size of the rake angle. Therefore, the drill point rake angle is not only closely related to the spiral angle, but also affected by the edge inclination.

What is the specification and model of twist drill?

Specification and size of twist drill: Φ 1.0、 Φ 1.5、 Φ 2.0、 Φ 2.5、 Φ 3.0、 Φ 3.2、 Φ 3.3、 Φ 3.5、 Φ 3.8、 Φ 4.0、 Φ 4.2、 Φ 4.5、 Φ 4.8、 Φ 5.0、 Φ 5.2、 Φ 5.5、 Φ 5.8、 Φ six Φ、 6.2、 Φ 6.5、 Φ 6.8、 Φ 7.0、 Φ 7.2、 Φ 7.5、 Φ 7.8、 Φ 8.0、 Φ 8.2、 Φ 8.5、 Φ 8.8、 Φ 9.0、 Φ 9.2、 Φ 9.5、 Φ 10.0、 Φ 10.2、 Φ 10.5、 Φ 11.0、 Φ 12.0、 Φ 12.5、 Φ 13.0、 Φ 13.5、 Φ 14.

 

Specification table of twist drill:

 

Straight shank twist drills GB/T,. 3 -, Φ 3- Φ 20

 

Straight shank twist drill GB/T,. 4 -, Φ 3- Φ 31.5

 

Morse taper shank twist drills GB/T,. 1 -, Φ 6- Φ。

 

Morse taper shank twist drill with standard handle and thick handle GB/T,. 2 -, Φ 6- Φ 50

 

Morse taper shank extended twist drill GB/T,. 3 -, Φ 6- Φ 30

 

Carbide straight shank twist drill, size 16.

 

The twist drill has a minimum diameter of 3.5MM, as well as 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 32 and other specifications.

 

The basic angle of twist drill includes four parts: top angle, cross edge angle, front angle and back angle.

 

1. Top angle: The included angle between two cutting edges of twist drill is called top angle. The angle is generally °, which can be smaller when drilling soft materials and larger when drilling hard materials.

 

2. Inclined angle of horizontal edge: the included angle between the horizontal edge and the main cutting edge is called the top angle, usually 55 °. The size of the diagonal angle of the horizontal edge varies with the size of the angle after grinding. When the back angle is large, the angle of the cross edge decreases, the cross edge becomes longer, and the circumferential force increases during drilling. If the back angle is small, the situation is opposite.

 

3. Front angle: generally – 30 °~30 °, maximum at the outer edge, and negative front angle near the center of the drill bit. The larger the spiral angle of twist drill is, the larger the front angle is.

 

4. Back angle: The back angle of twist drill also varies, with the minimum at the outer edge and the maximum near the center of the drill bit. It is generally 8 °~12 °.

 

Precautions for twist drill operation:

 

1. Twist drills shall be packed in special boxes to avoid vibration and collision.

 

2. A non-contact measuring instrument (such as a tool microscope) shall be used to measure the diameter of the drill bit to prevent the cutting edge from contacting the mechanical measuring instrument and being damaged.

 

3. When in use, the drill bit taken out of the packing box shall be immediately installed in the spring chuck of the spindle or in the tool magazine where the drill bit is automatically replaced.

 

4. Regularly check the same city of the spindle and spring collect and the clamping force of the spring collect. Poor same city will cause the drill bit with small diameter to break and the hole diameter to be large. Poor clamping force will cause the actual speed to be inconsistent with the set speed, and the chuck will slip with the twist drill bit.

 

5. For CNC machine tools with locating ring, the depth positioning during installation must be accurate. If the locating ring is not used, the elongation of the drill bit installed on the spindle must be adjusted consistently. For multi spindle drilling machines, this point should be paid more attention to, and the drilling depth of each spindle should be consistent. If they are not consistent, the drill bit may reach the floor or fail to drill through the circuit board, resulting in scrapping.

 

6. The 40x stereo microscope can be used to check the wear of the cutting edge of the drill bit.

 

7. Always check the spindle presser foot. The contact surface of the presser foot shall be horizontal and vertical to the main shaft without shaking, so as to prevent drilling break and deviation during drilling.

 

8. The clamping length of the fixed shank twist drill bit on the spring chuck is 4-5 times the diameter of the drill handle before it can be clamped firmly.

 

9. The base plate stack, including the upper and lower base plates, shall be firmly positioned and leveled in the one hole one slot positioning system on the workbench of the drilling machine. When using the adhesive tape, it is necessary to prevent the drill bit from adhering to the tape, which will cause difficulty in chip removal and drill break.

 

10. The drilling machine has a good dust suction effect. The dust suction wind can reduce the temperature of the drill bit, and at the same time, it can take away the dust to reduce friction and generate high temperature.

 

11. Timely regrinding can increase the use and regrinding times of twist bits, extend the life of bits, and reduce production costs and expenses.

 

 

 

Use of twist drill

 

What are the shapes and uses of various drill bits?

 

Use and classification of straight shank twist drills

 

The black straight handle twist drill is sharp. It is used to drill holes in wood and metal. The silver impact drill is blunt. It is used to drill holes in cement and brick walls. It is a construction drill. When drilling, the electric drill should be adjusted to have the impact function.

 

Best tool

 

Type and purpose of drill bit?

 

Now there are some golden surfaces coated with rare hard metal films, which are made of tool steel and other materials and hardened after heat treatment. A knife edge whose tip is ground to an equal angle on both sides with a slight backward inclination to form an acute angle. The drill has no steel, iron or aluminum hardened by heat treatment, and aluminum is easy to stick to the drill, so the drill needs to be lubricated with soapy water.

 

2. Punch holes in concrete materials and stone materials, use impact drills, cooperate with stone drills, and the cutting head is generally made of cemented carbide. Ordinary household use ordinary electric hand drills without drilling on cement walls.

 

3. Drill wood. Drill holes on wood materials and use woodworking drills together. The woodworking drills have a large cutting volume and do not require high tool hardness. The tool material is generally high speed steel. There is a small tip in the center of the bit tip, and the equal angles on both sides are relatively large, even no angle. For good fixing position. In fact, a metal drill can also drill wood. Because wood is easy to heat and brittle chips are not easy to come out, it is necessary to slow down the rotation speed and often exit to remove brittle chips.

 

4. Tile drills are used to drill holes on ceramic tiles and glass with higher hardness. Tungsten carbon alloy is used as the tool material. Due to the high hardness and poor toughness of the tool, attention should be paid to low-speed and impact free use.

 

 

 

Classification of twist drills

 

Type and purpose of drill bit? Come and have a look

 

2. Center drill bit: generally used to drill the center point before drilling.

 

3. Twist bit: It is the most widely used bit in industrial manufacturing. We generally use twist bit.

 

4. Super hard drill: The front end of the drill body or all of it is made of super hard alloy tool material, which is used for drilling of processing materials.

 

5. Oil hole drill bit: the drill body has two small holes through which the cutting agent reaches the cutting edge to take away heat and chips.

 

6. Deep hole drill: It was first used for drilling gun barrel and stone casing, also known as barrel drill. The deep hole drill is straight groove type.

 

What kinds of commonly used alloy twist drills are there?

 

Common alloy twist drills, straight shank alloy twist drills, fixed shank alloy twist drills, welded alloy twist drills, integral alloy twist drills, non-standard formed alloy twist drills are common types of alloy twist drills, OBS alloy twist drills!

 

What are the classifications of woodworking drills?

 

Three point drill, twist drill, gongs drill, flat drill.

 

Three point drill: woodworking three point drill, suitable for general wood drilling, screw holes, round wood mortise holes, etc. I bought a set at a special price of 20 yuan, from 3MM to a total of 8 pieces, which is said to be of export quality. There is also a small suit bought before. It seems that it is a four or five piece suit. It is shorter and gold coated. It is also very easy to use. The three-point drill should be the best for drilling wood. It is easy to locate, does not move, and is cheap.

 

Twist drill: Twist drill is generally used to drill metal. Different metals have different materials. I have bought more than 20 twist drills, and some of them are not concentric. Once the drill bit is clamped, it starts and shakes. Personal experience, it’s better to buy expensive twist drills, one for ten.

 

Flat drill: The flat drill is equivalent to scraping, because there is only one metal piece of the drill, which is perpendicular to the wood, so it acts as a scraper. Generally, cork can cope, but hardwood is embarrassed.

 

The gong drill has two knife edges, one of which is responsible for drawing a circle, which is equivalent to the role of a chisel, the other knife edge is responsible for shoveling, and the middle of which is a small screw, which is used as the center of the circle. The holes drilled by the gongs are neat, burr free and fast. Generally, the gongs and drills are long and used to drill deep holes.

 

Attention shall be paid during operation: because the contact surface between the drill body and the wood is large, the heat generated by friction is relatively large. If the wood is relatively hard, it often smokes. If the drill bit is not taken out in time to cool down, the drill bit will even be annealed and become weak.

 

Production of twist drill

 

Among the common twist drills on the market, there are white drills and black drills. Who can tell me the material, manufacturing process and use of these two drills?

 

The white drill is ground, so the precision of the white drill is higher than that of the rolling drill,

 

Both of them are made of M2 high speed steel. They can only process materials with lower hardness

 

General processing nonferrous metals, low carbon steel.

 

Of course, there are HSS-E,HSS-PM and other high speed steels that are difficult to machine

 

For example, alloy carbon steel, cast iron, stainless steel, etc.

 

What is the production process of twist drill?

 

From blanking to rough grinding, then to fine grinding, grooving, grinding the drill point, and then to fine grinding again, until packaging, labeling and shipping! Different kinds of twist drills produce different effects. For more than ten years, Zhijia has focused on the research, development and customization of twist drills!

 

What are the technical requirements for twist drills?

 

The appearance shall be free of cracks, chipping, burns, blunt cutting edges and other defects affecting the service performance.

 

The twist drill is a tool for drilling the round hole of the work piece through its rotary cutting relative to the fixed axis. It is named because its chip holding groove is spiral and looks like a twist.

 

Standard twist drill. The twist drill is composed of a handle, a neck and a working part.

 

(1) The diameter of twist drill is limited by the hole diameter. The spiral groove makes the drill core thinner and the drill bit has low stiffness; There are only two ribbed belts for guidance, and the axis of the hole is easy to deflect; The horizontal edge makes centering difficult, the axial resistance increases, and the drill bit is easy to swing. Therefore, the shape and position errors of drilled holes are large.

 

(2) The front and back tool surfaces of twist drills are curved surfaces. The front angle and back angle of each point along the main cutting edge are different, and the front angle of the cross edge is – 55 °. The cutting conditions are very poor; The cutting speed distribution along the cutting edge is unreasonable, and the cutting speed of the tool tip with the lowest strength is the maximum, so the wear is serious. Therefore, the machined hole accuracy is low.

 

(3) The main cutting edge of the drill bit is full edge, and the cutting speed of each point on the cutting edge is not equal, so it is easy to form spiral chips and difficult to remove chips. Therefore, the chip often scratches the hole wall due to extrusion and friction with the hole wall, and the surface roughness after machining is very low

 

Although the geometric shape of twist drill is more reasonable than that of flat drill, there are still the following shortcomings:

 

(1) The difference between the front angle values at each point on the main cutting edge of the standard twist drill is too large. The front angle of the main cutting edge at the outer edge of the drill bit is about+30 °; The front angle near the drilling center is about – 30 °, and the front angle near the drilling center is too small, resulting in large chip deformation and large cutting resistance; However, the front angle near the outer edge is too large, and the cutting edge strength is often insufficient when machining hard materials.

 

(2) The horizontal edge is too long, and the front angle of the horizontal edge is a large negative value, up to – 54 °~- 60 °, which will generate a large axial force.

 

(3) Compared with other types of cutting tools, the main cutting edge of standard twist drills is very long, which is not conducive to chip separation and chip breaking.

 

(4) The back angle of the auxiliary cutting edge at the edge band is zero, resulting in increased friction between the back face of the auxiliary cutting edge and the hole wall, increased cutting temperature, greater wear at the corner of the outer edge of the drill bit, and deterioration of the machined surface roughness.

 

 

 

 

 

                                                                                                                                                                     Diane

 

Phone/Whatsapp:8618622997325

 


Post time: Oct-13-2022