twist drill
Twist drill is the most widely used hole processing tool. Usually the diameter ranges from 0.25 to 80 mm. It is mainly composed of a bit working part and a handle. The working part has two spiral grooves, which are shaped like twists, hence the name. In order to reduce the friction between the guide part and the hole wall during drilling, the diameter of the twist drill gradually decreases from the drill tip to the handle, showing an inverted cone shape. The helix angle of twist drill mainly affects the rake angle of cutting edge, blade strength and chip removal performance, usually 25 ~ 32. The spiral groove can be processed by milling, grinding, hot rolling or hot extrusion, and the front end of the drill bit is sharpened to form a cutting part. The top angle of standard twist drill cutting part is 1 18, the oblique angle of cross blade is 40 ~ 60, and the back angle is 8 ~ 20. Due to structural reasons, the rake angle is larger at the outer edge and gradually decreases towards the middle, and the rake angle of the transverse edge is negative (up to about-55), which plays a squeezing role during drilling. In order to improve the cutting performance of twist drills, the cutting parts can be ground into various shapes (such as group drills) according to the properties of the processed materials. There are two kinds of handles for twist drills: straight handles and tapered handles. When machining, the former is clamped in the drill chuck, and the latter is inserted into the cone hole of the spindle or tailstock of the machine tool. General twist drills are made of high-speed steel. Twist drills with cemented carbide blades or crowns are suitable for processing cast iron, hardened steel and nonmetallic materials, and integral cemented carbide small twist drills are used for processing instrument parts and printed circuit boards.
spade drill
The cutting part of the flat drill is shovel-shaped, with simple structure and low manufacturing cost. Cutting fluid is easy to enter the hole, but its cutting chip removal performance is poor. The structure of flat drill has two kinds: integral and assembled. Integral drilling is mainly used for drilling micropores with a diameter of 0.03 ~ 0.5 mm, and the assembled flat drill blade can be replaced and internally cooled, and it is mainly used for drilling large holes with a diameter of 25 ~ 500 mm.
deep-hole drill
Deep hole drill usually refers to a tool for processing holes with the ratio of hole depth to hole diameter greater than 6. Commonly used are gun drill, BTA deep-hole drill, jet drill, DF deep-hole drill and so on. The trepanning drill is also commonly used for deep hole machining.
ream
Reamer has 3 ~ 4 teeth, and its rigidity is better than that of twist drill. It is used to enlarge existing holes and improve machining accuracy and flatness.
ream
Countersunk drill has many cutter teeth, and the hole end is processed into the required shape by forming method, which is used to process countersunk holes of various countersunk screws or flatten the outer end face of the holes.
center drill
The center drill is used to drill the center hole of shaft workpiece, which is essentially composed of twist drill and small spiral angle countersunk drill, so it is also called compound center drill.
[Edit this paragraph] bit structure
A drill bit includes a tool holder (1) with a tip with two cutting blades (5, 5') located on a main plane (c-c), and the cutting blades (5, 5') have short central cutting edges oriented on a second plane (e-e). The cutting edge forms a point-like central cutting edge for entering the workpiece, thus centering the drill bit. Two chip removal grooves (6, 6') are arranged on the tool holder, and the chip removal grooves (6, 6') extend from the tip to the bottom. On any cross section along the tool holder, the chip removal grooves are located at radially opposite positions to each other on the pipeline plane, which extends at 90 degrees with the same blade plane (F-F) of two blades on both sides of the pipeline, and the tool holder has the maximum rigidity in this plane. The orientation of the second plane (e-e) of the central cutting edge makes an angle of about 90 degrees with the plane of the land or the main rigid direction (f-f) of the bottom end of the tool holder.
The invention provides a drill bit, which can alleviate the sudden change of drilling state in drilling operation of concrete and the like, make the drilling operation stable, and will not reduce the drilling efficiency even if large chips are generated.
The cutting edge portion is arranged in a radial shape and has at least two main cutting edge portions and at least two auxiliary cutting edge portions arranged between the main cutting edge portion and the main cutting edge portion in the circumferential direction. The main cutting edge part is provided with a main cutting edge as its cutting edge, and the inner end of the main cutting edge is located at the rotation center and the outer end is located at the outer edge of the rotation track of the cutting edge part.
The auxiliary cutting edge part has an auxiliary cutting edge as its cutting edge, and the inner end of the auxiliary cutting edge is located at a position deviated from the rotation center toward the outer diameter side, while the outer end is located at a position deviated from the outer edge of the rotation track of the cutting edge part toward the rotation center side.
A drill bit is provided with a plurality of cutting edges arranged at the front end of the drill bit, and a shaft-shaped drill bit body arranged at the base end side of the cutting edges and provided with a handle part formed at the base end;
The cutting edge portion has a cutting edge formed by projecting the joint edge of the cutting surface and the clearance surface to the front end side, and the cutting edge is arranged in a substantially radial shape from the drill rotation center side to the outer diameter side;
Characterized in that the cutting edge part has at least two main cutting edge parts and at least two auxiliary cutting edge parts arranged between the main cutting edge part and the main cutting edge part in the circumferential direction;
The main cutting edge part has a main cutting edge as its cutting edge, the inner end of the main cutting edge is located at the rotation center, the outer end is located at the outer edge of the rotation track of the cutting edge part, and the sub cutting edge part has a sub cutting edge as its cutting edge. The inner end of the auxiliary cutting edge is located at a position deviating from the rotation center to the outer diameter side, and the outer end is located at a position deviating from the outer edge of the rotation track of the cutting edge part to the rotation center side.
[Edit this paragraph ]PDC bit
brief introduction
Short for PDC bit [1]. It is a common drilling tool in oil drilling industry.
The performance of PDC products is constantly improving.
In the past few years, the quality and types of PDC cutting teeth have changed greatly. If we compare the teeth of the 1980s with those of today, the difference is quite big. Due to the change of mixing technology and manufacturing technology, the quality and performance of today's cutting teeth are much better, which greatly improves the erosion resistance and impact resistance of the drill bit.
Engineers also optimized the interface between tungsten carbide substrate and synthetic diamond to improve the toughness of cutting teeth. The innovation of layered diamond technology is also used to improve the wear resistance and thermal stability of products.
In addition to the development of materials and manufacturing technology, PDC products have achieved a major breakthrough in the design technology and layout of bucket teeth. Now, PDC products can be used in previously unusable fields, such as harder, more wear-resistant and variable formations. This expansion to new fields has a great influence on the balance between diamond (fixed cutting teeth) bit and roller bit.
Initially, PDC bit can only be used in soft shale formation, because hard interlayer will damage the bit. However, due to the emergence of new technology and structural changes, PDC bits can be used to drill hard interbeds and long hard rocks. PDC bits are used by more and more people, especially with the continuous improvement of PDC tooth quality.
Due to the improvement of bit design and teeth, the directionality of PDC bit has also been improved, further weakening the advantages of roller bit in motor drilling in the past. At present, PDC bits occupy the market of roller bit in many strata drilling applications every day.
Commonly used mechanical drills include straight shank twist drills (common type), which can be used to drill 45# steel and stainless steel. Using alloy bit, Cr 12 steel can be drilled, and hard materials can be used. Using the professional knowledge of drillers can reduce profits.
PCB bit type
Bit types of PCB drilling control drilling machine: PCB drilling includes straight handle twist drill, fixed handle twist drill and fixed handle undercut drill. Straight shank twist drills are mostly used in single-head drilling machines to drill simple printed boards or single boards, but now they are rarely seen in large circuit board manufacturers, and the drilling depth can reach 10 times of the drill diameter. When the basement pile is not high, drilling deviation can be avoided by using drilling sleeve.
At present, the CNC drilling machines used by most manufacturers use cemented carbide fixed handle drills, which are characterized by automatic replacement of drills. High positioning accuracy, no need to use a drill sleeve. Large helix angle, fast chip removal speed, suitable for high-speed cutting. Within the full length of the chip removal groove, the diameter of the drill bit is inverted cone, which has small friction with the hole wall and high drilling quality. Common drill shank diameters are 3.00 mm and 3. 175 mm. ..
Bit material
Generally, cemented carbide is used as the drill bit for PCB drilling, because the epoxy glass cloth copper clad plate wears the tool very quickly. The so-called hard bit gold is made of tungsten carbide powder as matrix and cobalt powder as binder by pressing and sintering. Usually it contains 94% tungsten carbide and 6% cobalt. Because of its high hardness, wear resistance and certain strength, it is suitable for high-speed cutting. However, its toughness is very poor and it is very brittle. In order to improve the properties of cemented carbide, a layer of superhard titanium carbide (TIC) or titanium nitride (TIN) with a diameter of 5 ~ 7 microns was deposited on the carbonized matrix by chemical vapor deposition, which made it have higher hardness. Some use ion implantation technology to implant titanium, nitrogen and carbon into their matrix to a certain depth, which not only improves the hardness and strength, but also allows these injected components to move inward when the drill bit is reground. Others use physical methods to form a diamond film on the top of the drill, which greatly improves the hardness and wear resistance of the drill. The hardness and strength of cemented carbide are not only related to the proportion of tungsten carbide and cobalt, but also related to the particles of powder. The average size of tungsten carbide particles in ultra-fine cemented carbide bit is below 65438 0 micron. This kind of drill bit not only has high hardness, but also has improved compressive and bending strength. In order to save cost, many drill bits now adopt welding handle structure. The original drill bit was made of cemented carbide as a whole, and now the drill handle behind it is made of stainless steel, which greatly reduces the cost. However, due to the different materials used, its dynamic concentricity is not as good as that of the whole cemented carbide bit, especially when the diameter is small.
Use of drill bit
1. Drill bits should be packed in special packing boxes to avoid vibration and collision.
2. When in use, the drill bit can be automatically replaced by taking it out of the packaging box and putting it into the spring chuck of the spindle or the tool magazine. Put it back in the box immediately after use.
3. Non-contact measuring instruments such as tool microscope should be used to measure the diameter of the drill bit to avoid the cutting edge from being scratched due to contact with mechanical measuring instruments.
4. Some CNC drilling machines use locating rings. Some CNC drilling machines do not use locating rings. If a locating ring is used, the installation depth must be accurate. If the locating ring is not used, the extension length of the drill bit installed on the spindle should be adjusted to be consistent. Multi-spindle drilling machines should pay more attention to this point, so that the drilling depth of each spindle is consistent. If it is inconsistent, it may make the drill bit drill to the table or drill through the circuit board, resulting in scrapping.
5, usually can use 40 times the stereoscopic microscope to check the wear of the bit edge.
6. Be sure to check the concentricity of the spindle and the spring chuck and the clamping force of the spring chuck. Poor concentricity will lead to the fracture of the drill with small diameter and large aperture. Poor clamping force will lead to the inconsistency between the actual speed and the set speed, and the chuck and drill will slip.
7. The clamping length of the fixed handle drill on the spring chuck is 4 ~ 5 times of the diameter of the drill handle, so that it can be clamped firmly.
8, often check the spindle presser foot. The contact surface of presser foot should be horizontal and vertical to the spindle to prevent broken drilling and eccentric drilling.
9. The drilling machine has better dust absorption effect. Dust suction wind can reduce the temperature of the drill bit, and colleagues take away dust to reduce friction and produce high temperature.
10. The substrate stack, including the upper and lower pads, shall be firmly positioned and leveled in the one-hole and one-groove positioning system on the drilling table. When using the adhesive tape, it is necessary to prevent the drill bit from sticking chips when drilling on the adhesive tape, which will make it difficult to remove chips and break the hole.
1 1. 4% of the drill bits ordered by the manufacturer shall be checked for compliance when entering the factory for inspection. Among them, 100% was examined by microscope 10 ~ 15 times.
12, regrinding the drill bit in time can increase the use and regrinding times of the drill bit, prolong the life of the drill bit and reduce the production cost and expense. Usually, measured by a tool microscope, the wear depth of the two main cutting edges should be less than 0.2 mm. When regrinding, 0.25mm should be removed. Ordinary fixed-shank drills can be reground three times, and root-cutting drills can be reground twice. Too much grinding will reduce the quality and accuracy of drilling, leading to the scrapping of finished circuit boards. Excessive grinding will have the opposite effect.
13. When the wear diameter is reduced by 2%, the drill bit is scrapped.
14, bit parameter setting In general, the manufacturer provides a table of drilling speed and deceleration parameters of the bits produced by our factory for reference only. In fact, technicians need to get a bit speed and deceleration parameter that accords with the actual situation through practical use. Usually, the actual parameters and reference parameters are different, but the difference is not too big.
Concept of drill bit
A drill bit is a tool for drilling through holes or blind holes in solid materials and enlarging existing holes. Commonly used drill bits mainly include twist drill, flat drill, center drill, deep hole drill and casing drill. Although reamers and countersinks cannot drill holes in solid materials, they are customarily classified as drill bits.