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1. High speed steel hole machining tool 7. CZD _ kolb
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High speed steel hole machining tool is still the main part of hole machining tool. According to the statistical data of the former GDR in 85 years, the output value of high-speed steel drilling and boring tools accounts for 79.8% of the total output value of drilling and boring tools, cemented carbide drilling and boring tools account for 20%, ceramic tools and superhard material tools each account for 0. 1%. pzjS@whk|P
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1. 1 high speed steel twist drill 8cLC3Fp
High speed steel twist drill is still one of the most widely used metal cutting tools. For example, in machining in Germany, about 50 million twist drills are consumed every year, and most of these twist drills are φ 6 ~ 14 mm in diameter. The annual output of high-speed steel twist drills in China has reached 300 million, accounting for about 36% of the annual output value of tool products. ]5 \H'_
High-speed steel twist drill has been used in production for decades, and its basic shape has not changed. The problems existing in the drilling process of twist drill are as follows: the rake angle of each point on the main cutting edge is very different; The transverse blade is long and the axial force is large; The cutting speed of drill bit varies from place to place; The back angle of the blade belt is zero, which causes friction with the hole wall and accelerates wear. To this end, we must improve these problems, but it is difficult to completely eliminate them. Judging from the current situation, the main improvements are: B6; k，
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1. 1. 1 increase helix angle ]tI9+
In order to adapt to the characteristics of the material to be cut and the rhythm of the efficient production line, some newly designed twist drills have chosen a higher cutting speed (40 ~ 50m/min). Parabolic twist drill with increased helix angle (called parabola drill in America, auger drill in Britain, GT drill in Geling, Germany, parabola drill in Shanghai Tool Factory and Jiangxi Measuring Tool Factory, etc. ) just adapted to this demand. Its main features are: (uFqj4[m]
(1) The helix angle is large (generally 35 ~ 45) and the vertex angle is large, thus increasing the rake angle of the bit and making the cutting sharp; ~ = w)I | G；
(2) The chip holding space is large, so that chips can be discharged smoothly; T853 USD [m@5
(3) The greater the core thickness, the greater the rigidity; & amp& gtDW3Y77
(4) The cross grinding method or S-shaped grinding method is used to grind the cross edge, which shortens the cross edge, improves the rake angle of the center and the core, has light cutting and small axial force, and can process holes with considerable depth at one feed, thus improving the working efficiency. It has obvious advantages over the traditional drilling rig. |/Z？ 0L/qi
Greencool's GT drills are divided into GT50 and GT 100, among which GT50 is used to drill soft materials that can form long chips, such as aluminum, aluminum alloy, zinc, copper and wood. GT 100 is used for drilling steel and cast iron with hardness below 3 1HRC. . bC0Yc#/
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1. 1.2 improving the working conditions of the blade uv] o6hi2
Due to the great axial force on the cross blade of twist drill, people pay more and more attention to improving the working conditions of the cross blade. There are two main ways to improve:&; )& amp@QI%
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Pay attention to improving grinding method -QT6
There are six main types of drill point grinding, namely, ordinary grinding, spiral grinding, comprehensive grinding, three-sided grinding, cross grinding and circular arc grinding. Experiments show that the spiral grinding method has good position accuracy, the cross grinding method is suitable for deep hole machining, and the circular arc method is easy to center. The most promising method is cross and arc grinding. vYep & gt@]g
Cross sharpening method shortens the transverse edge and reduces the axial force, which is very popular in Europe, America and Japan recently. In the grinding process, the symmetry of the two cutting edges must be maintained. The test shows that the service life of the cross grinding method is doubled, the axial force is reduced by 30% ~ 60%, the torque is reduced by 13% ~ 30%, and the chip removal is smooth, but the thickness of the drill core needs to be thickened. iOByJ# ` '
The outer edge of the drill tip wears quickly, which will make the sharp cutting edge turn into arc for a long time before the tool wears, so the arc grinding method is developed. The cutting pattern of circular arc drill tip is lengthened, and the heat dissipation condition is good, which improves the service life of the drill bit; In addition, the cross blade is polished and the front angle distribution is reasonable; Burrs and flash are rarely produced when drilling. The key is that the grinding arc requires symmetry, and the arc can be controlled by hand and template. The successful development of the arc drill point grinder in ingersoll, USA, promoted the development of the arc drill point. & ltAA*V@r%5
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Five special grinding methods of drill tips in DIN1412 >: +Rh? Syria
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DIN 14 12 lists five special grinding methods for drill tips, among which Type A is called cross edge grinding, Type B is called cross edge grinding plus grinding, Type C is called split drill tip, Type D is double rake angle type for cutting cast iron, and Type E is nail drill tip. )8 ~ & amp@xv
According to the principle of conical surface grinding, Beihang University in China has designed a seven-coordinate CNC drill point grinder with the model of CNC-7DGA, which can complete many processes such as grinding the back of the outer edge, grinding the round edge, grinding the cross edge and grinding the single chip separator in one clamping period, which will improve the grinding level of the drill point and ensure the grinding quality of the drill point. pk。 }
Choose a reasonable edging method iV2]r3.
In order to overcome the bad cutting conditions such as negative rake angle at the chisel edge and reduce the axial force, the method of grinding the chisel edge is often used to solve it. At present, there are five kinds of commonly used grinding blades: S, N, W, X and S-X. The S-shaped edge is trimmed with 2/3 transverse edges to reduce the axial force and discharge the chips upwards. N-type is suitable for thinner cores to discharge chips upward. W type (B type in DIN 14 12) has good cutting performance and alignment, but its rigidity is poor when the thickness of the core decreases along the whole groove. X-type transverse blades (that is, C-type in DIN 14 12) are completely trimmed, which is the one that reduces the axial force the most. S-X cutter head has good strength and easy chip removal, which can improve machining efficiency and accuracy. p'@ 'Kt
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1. 1.3 improving cooling conditions JWi]D+p
In improving the cooling conditions of high-speed steel twist drill, in addition to increasing the chip groove to make the cutting fluid enter the cutting area more smoothly, the use of oil hole drill has also become a powerful tool. 3! MW> Extensible Stylesheet Language (short for Extensible Style Sheet Language)
For example, twist drills with oil holes with large helix angles have been widely used in CNC machining centers recently. In order to give full play to its performance in use, Cleveland Twist Drill Company of the United States recently conducted a large number of comparative tests between oil hole twist drills and ordinary twist drills, and also studied the relationship among large feed rate, service life of drill bit and total cutting cost. The results show that the cost per hole can be reduced by more than 32%. Compared with the common twist drill, it can greatly improve the productivity, thus greatly reducing the production cost. The reduction of total cost depends on tool life, which is a function of feed. There are five kinds of oil hole twist drills produced by Germany's Guehring company from ordinary high-speed steel and cobalt high-speed steel, such as ordinary type and GT 100 (with large helix angle), with the specifications of ordinary type being φ 10 ~ 50.8 mm and GT 100 being φ1. French Forecreu company adopts modern technological methods (forging, rolling, drawing, twisting, grinding and heat treatment, etc.). ) To manufacture this patented round steel with holes, realize the industrial scale production of round bar high-speed steel with one or several spiral through holes or through holes, and provide semi-finished products for manufacturing oil hole drills. The company's product specifications are bar diameter φ 2.2 ~ 65 mm and bar length 8m. \5}，y6！
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1. Arc-edged drill ` \f~eN9
Tap&Die Company introduced the patented EX-Gold circular-arc cutting edge drill with unique design. The cutting edge is an arc cutting edge, and it adopts three-sided grinding after drilling, which has good cutting performance and chip breaking performance. It can directly remove chips without exiting the drill bit during machining; High precision and long service life. An aircraft factory in the United States needs to drill φ 13.5mm 180 high-precision holes on parts made of 4340 steel (roughly equivalent to 40Mo) with hardness of 38 ~ 40hrc. In the past, cobalt high-speed steel bit was used for processing. In order to ensure the quality and accuracy of the hole, it is necessary to retreat for 4 ~ 5 times each time, which is inefficient and has the problem of out-of-tolerance of the hole diameter. In order to overcome this main processing obstacle, the aircraft manufacturer chose EX-Gold drill to finish the hole processing of the above materials, which solved the problems caused by the above cobalt high-speed steel drill, improved the production efficiency and reduced the processing cost. The user's application shows that this new structure bit is an efficient drilling tool for fine hole processing. 7GV0D7
2. double-edged drill YZ? % ai6L & gt
Reduce the friction of the cutting edge, develop into a double-edged drill, and grind the relief angle at the first edge, reduce friction and wear, avoid burns, and improve life and accuracy. 4p 'pOL
3. Shorten the length and improve the rigidity
CNC machine tools require high efficiency, which inevitably requires the drill to have high rigidity. As a result, short drill bits with shorter drill length and larger cross-sectional area appeared, which were listed in international standards one after another, such as German standard DIN 1897. Virtual trip! Yu;
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1.2 center drill (outer diameter Q`Y USD
As we all know, the central hole is the reference hole to ensure the machining accuracy of shaft parts. Because the 60 conical surface of the central hole is not only the positioning benchmark during machining, but also the benchmark for future maintenance, whether the central hole is suitable is the key to determine the machining quality of shaft parts, so it can be seen that the machining of the central hole is very important. In recent years, with the rapid development of machinery industry, the requirements for the central hole of shaft parts are getting higher and higher. For example, what are the requirements for roundness and coaxiality of parts machined on high-precision machine tools 1 ~ 2? M, 0.2 ~ 0.5 for machining on ultra-precision machine tools? M. In short, according to the machining requirements of shaft parts, the central hole must reach a certain machining accuracy and surface roughness, and the 60 conical surface should have a certain width, and there should be no defects such as vibration lines, burrs and gnawing knives. Machining the center hole requires a center drill. There are three main types of center drills produced in China: type A-unprotected cone; B-type with protective cone and R-type with circular arc have an annual output of millions in China and are widely used, among which there are mainly two types: A-type and B-type. #cpo^%·e
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1.2. 1 Structural defect of common center drill OXI_=h8uE
At present, there are some problems in the structure of the center drill widely used in production, mainly: VKT "IG,
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1. The drilling part of the center drill is relatively long. Due to the low cutting speed (V < 10m/min), uneven manual feed and uneven end face of the shaft, it is usually easy to break. Me! Service $J#n
2. The width of the 60 taper surface of the center hole machined by the center drill is varied. If it is too narrow, the contact area between the conical surface and the tip is small, and the cutting force is large, the workpiece will slip out of the tip hole, and the tool workpiece will be damaged, causing machine tools or personal accidents. However, if it is too wide, it is easy to make the shape of the workpiece become polygon, and the surface will appear vibration lines, which will increase the roughness of the machined surface and affect the machining accuracy of shaft parts (such as radial runout, roundness, taper, coaxiality, etc.). ). In addition, due to the different width of the 60 conical surface of the central hole, the axial dimensions of a batch of parts processed will be different. BQ0 CO:P；
3. Usually, there is a certain regrinding allowance (about 0.4 ~ 0.6 mm) in the drilling part of the standard center drill, but in most cases, this part has been broken and has not been sharpened. For this reason, some people use the new center drill by properly grinding the drilled part before using it. However, there will also be problems, because if the grinding is too short, the tip of the top on the machine tool will easily directly touch the bottom of the central hole, resulting in poor contact between the tip and the conical surface of the central hole, which will lead to inaccurate positioning of the workpiece and out-of-roundness error of the processed shaft parts. If the top of the coat is polished to a certain extent, although it has some effects, it is unreasonable and does not meet the technological requirements. Generally speaking, according to the machining accuracy requirements of parts, when drilling with φ 2 ~ φ2~3. 15mm center drill, the width of 60 cone is about1.5 ~ 2.5 mm. */] rsst <;
As can be seen from the above, there are some shortcomings in the structure of the ordinary standard center drill, and improper use will often affect the service life, processing quality, processing efficiency and processing cost of the center drill in the processing process. Therefore, in recent years, through scientific analysis and experimental research at home and abroad, the cutting performance, service life and machining quality have been improved by improving the structure of the center drill. Therefore, several new types of center drills have been developed and achieved good results in application. Y%799|B！ null hypothesis
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1.2.2 center drilling of circular arc blade < {qgVO|E}
According to the structural characteristics of ordinary standard center drills, especially small center drills, the drill part is often too long and easy to break when processing hard materials. The strength of center drills can be improved by appropriately shortening the length of the cylindrical drill part of standard center drills and increasing its diameter. However, the hole drilled in the center of the circular-arc blade is not conical but circular-arc, so the contact part between it and the center of the machine tool is a circular or narrow conical annular zone, which can improve the roundness of the excircle of the workpiece when machining shaft parts. Of course, the manufacture of circular-arc edge center drill is more troublesome. uhfo:JgRk
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1.2.3 drill 1Kzuj+a in the center of the spiral groove.
The center drill used in China has a straight groove shape. Although this structure is convenient to manufacture, the cutting performance is not ideal, the chips are not easy to be discharged automatically, and the service life of the tool is short. Spiral groove center drilling can overcome these shortcomings. Foreign tool manufacturers, such as the United States and Germany, can produce straight groove and spiral groove center drills and set standards. The comparative test shows that the center drill of spiral groove is easy to cut, and silver-white strip-shaped continuous chips are obtained, with clear cutter line, bright hole wall, no edge collapse and obvious wear. Under almost the same cutting conditions, the durability of spiral groove center drill is 4 times higher than that of straight groove center drill. 1h & amp； /*%j
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1.2.4 center drill with spherical parts cVR']Q
Spherical center drill is an improved structure abroad. Its central drill consists of three parts: cylindrical drilling part, spherical part and conical part. Its characteristics are: C"_js`QFe.
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1. The length L of the cylindrical drilling part is shorter than that of the ordinary standard center drill, so it has higher strength and rigidity. pLNdL 1d
2. Because a reaming part is added to the center drill, on the one hand, the width of the cone surface of the center hole drilled is narrow, which is more reasonable. Especially for high-precision shaft machining, after machining the center hole with standard center drill, the technological requirements can be met only by reaming the hole once, and this process is no longer needed for drilling with center drill of spherical part. On the other hand, the reaming length of the center drill can ensure the depth of the center hole. [E % #
3. The center hole machined by ordinary standard center drill is often difficult to grind after hardening due to the wide shallow conical surface of the hole, while the conical surface of the center hole with spherical part is narrow, which improves the contact conditions of the center hole. W)8fv？
4. Because of the large space, the central hole with spherical part is convenient for storing lubricating oil, which ensures that the 60-degree conical surface is fully lubricated and reduces friction and heat. Compared with the standard center drill, it is beneficial to improve the machining accuracy of shaft parts. t *$E
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1.3. 1 main problems of high-speed steel reamer `| hlhq ~
High-speed steel reamer often produces various errors when reaming, such as size and shape errors, reaming expansion or contraction, flaring and polygonal holes, large surface roughness and waviness. r？ k7nLe`r
After analysis, the reasons for the above phenomenon are as follows: uls' 8' i.
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1. The cutter teeth of the straight reamer are not strictly controlled on a circle. When reaming, the load on the cutter teeth changes periodically, and the cutting depth is uneven, which leads to chatter, which makes the surface roughness of reaming worse, and may even lead to polygons and even "gnawing holes". sx 32 cy；
2. When manufacturing reamer, the cutter teeth have radial runout. NxCSpRzW
3. After the reamer is used for a period of time, the cutter teeth are worn, resulting in the phenomenon that the cutter teeth are unequal in height. = NOz & amp“v9
4. The processed matrix material is uneven and the hardness is inconsistent. The quality of the holes formed in the previous process is not high. b8 & gt}UOth
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1.3.2. 1 Increase chip space J6' 0' 8 [lk%.
Because reaming belongs to closed cutting, in order to avoid chip blockage and ensure the surface quality of machined holes, there must be enough chip accommodation space on the premise that reamer teeth have sufficient strength. The measures to increase the chip space of reamer are as follows: yffe
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1. Reduce the reaming allowance appropriately. zl。 rnj
2. Appropriately increase the depth of the chip groove. 4+M 1kQa
3. Use a folded or curved tooth back. p:ge } 3E[6；
4. Reduce the number of teeth of reamer appropriately. For example, in some factories, the front end of the cutting part of the standard reamer is worn off at intervals to increase the chip space and improve the cooling conditions. The cutter tooth length of 1/4 is reserved at the back end for polishing, calibration and guidance. This can greatly reduce the surface roughness and improve the durability of reamer in machining deep holes in steel and castings. %ZN|X！ %qW
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1.3.2.2 Unequal spacing and la; ~
The common reamer is simple to manufacture and the pitch distribution is uniform, but it can only meet the requirements of general machining accuracy. When reaming a hole, if the cutter teeth touch hard particles in the processed material, the cutting force will suddenly increase, and the reamer will lose its balance and vibrate, pressing out longitudinal dents on the hole wall. If equal pitch distribution is adopted, each cutter tooth will encounter a hard point, and longitudinal dents will be repeatedly generated in the original place, which will deepen the dents and make the surface of the hole wall rough, even oval or polygonal. In order to improve the quality of machined surface, unequal pitch distribution can be adopted. Usually, for the convenience of manufacture and measurement, unequal pitch distribution with equal angle between top teeth is adopted. A reamer with unequal pitch is recommended abroad. For example, if the number of teeth is 6, it will be machined with unequal pitches of 45, 60 and 75, so that each cutter tooth will not repeatedly cut into the notch of the previous cutter tooth when reaming. Therefore, the accuracy of machining holes can reach H5, and the roundness error can be as small as1~ 3? M, and can reduce the surface roughness, even replace the inner hole grinding, so it is suitable for machining the guide hole of the valve, the cylinder hole of the jet pump, etc. % ~ cQzj & gt
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1.3.2.3 development of screw reamer -> C' NZ}?
The hole reamed by ordinary reamer has a large roundness error, and the reaming process is unstable and prone to vibration, especially when reaming conical holes, it often produces high-frequency vibration, which affects the reaming quality. Therefore, the thread reamer has been developed at home and abroad. J'm-RZRx#
Spiral reamer is to improve the straight tooth profile of ordinary reamer into spiral tooth profile. Its advantages are continuous cutting and stable working process, which can greatly improve the cutting performance of reamer Using spiral reamer to form inclined plane cutting can make chips discharge smoothly, improve the strength and rigidity of reamer, and is not easy to cause edge collapse and vibration; In practical work, the large rake angle and sharp cutting edge can avoid the adhesion and galling of tough materials, thus reducing the surface roughness of the hole wall. @ & Punish
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2. Carbide hole machining tool
2. 1 development of micro cemented carbide monolithic bit >: M@JTN, ]*D
With the development of aerospace, electronic industry, light industry and medical equipment, the development of integral cemented carbide small drill bit has been promoted. Micro-hole drilling often requires rotating speed as high as (1~12) ×104 r/min. In order to improve the rigidity of the drill bit, this kind of small drill bit mostly adopts fine cemented carbide material with high toughness and bending strength. Structurally, less than? 1mm bit often adopts thick shank, and short integral cemented carbide bit with slightly larger diameter is used. Vibration reduction, centering, chip removal and cooling should be paid attention to when using the integral cemented carbide small drill bit, and sensors should be generally used for monitoring. For example, MIT has developed an isotope monitoring method for monolithic cemented carbide drill bits. & ampZ ' & lt\xZ^F
Japan Toshiba Tungsten Co., Ltd. Small diameter drill is divided into UH (? 0. 1~0.3mm)、RH(？ 0.3~ 1.65mm)、COS(？ 1 ~ 6mm). The Soviet Union BHNN also developed? The service life of cemented carbide bits with 0.4~2mm thick shank is 100 times that of high-speed steel bits of the same specification. Test instructions, with? 0.8 ~ 8 mm straight shank cemented carbide drill has achieved good results in processing difficult-to-machine materials and heat-resistant alloy materials. Amplx company in the United States has developed a series of electroplated diamond integral small drills, which can drill holes. 0. 13 ~ 0.5 1 mm pinhole. According to foreign reports, what is the smallest diameter of the whole cemented carbide bit? 0.02 ~ 0.03 mm. HPw e_C
With the development and increasing use of printed circuit boards to meet the requirements of small size, light weight, high density and high reliability, the accuracy of holes is getting higher and higher, the aperture is getting smaller and smaller, and the distribution density of holes is getting larger and larger, which brings various difficulties to the micro-hole processing of these printed circuit boards. As a special drill for printed circuit board, the material and shape of the drill will also change with the type of printed circuit board and the depth of the hole. Generally speaking, the cutting performance of paper, phenolic resin printed circuit board or glass fiber and epoxy resin printed circuit board is better, while the material with copper layer on the surface has a great influence on the cutting performance. For multilayer boards, there is a layer of copper inside the printed circuit board. Generally speaking, the thickness of the surface copper layer is 18 ~ 35? M, the thickness of the inner copper layer is 35 ~ 70? M. This copper layer has a great influence on the wear of the drill bit. The thicker the copper layer, the higher the fracture rate of the bit. Therefore, the cutting amount for processing multi-layer plates is less than that for processing copper plates with two sides attached, especially when the diameter of the drill bit is small. In order to reduce the damage of drill bit, the ratio of the thickness of drill core to the thickness of drill groove is often changed to increase the cross-sectional area of drill bit and improve the rigidity of drill bit. Recently, a new type of MD cemented carbide has been developed, which can reduce the friction during drilling, that is, reduce the contamination phenomenon, have good wear resistance and long service life, and can meet the needs of high-speed and efficient production of printed circuit boards. ; T`, r3
2.2 Medium-sized cemented carbide bit $ = NZ6Al
2.2. 1 three-edge solid carbide drill @i.muGT
The characteristics of three-edge solid carbide drill are: +f~J=\. \ 8 & gt
1. Compared with the double-edged drill, the core is thicker and stronger, which makes up for the weakness of poor toughness of cemented carbide; QV2K \ G. & ltw
2. The front end of the tool tip has a special shape, which can automatically center when cutting, without machining the center hole; 9[) kg \ |%
3. Because there are more blades, the feed per revolution increases (up to 20m/min when cutting aluminum), and high-speed cutting can be carried out (up to 1000m/min when cutting aluminum), which greatly shortens the processing time; iSaI:？ mendelevium (Md)
4. The machining accuracy is high, the dimensional accuracy reaches H9, the position accuracy is 0.0 1 1mm, and the roughness RZ is 20-25? m； c = bR[]% ~ _
5. Long service life: the processed alloy steel, cast iron and aluminum alloy can reach 20m and 80m respectively. _
6. It is easy to regrind, and no special grinding tool is needed. This drill is suitable for machining holes of the following materials, the hole depth is 3-4 d: low alloy, titanium alloy, austenitic manganese steel, hard bronze, high hardness cast iron and silicon-aluminum alloy. When processing austenitic manganese steel and titanium alloy, the cutting speed can reach 40m/min, and when processing aluminum alloy, the cutting speed is 130m/min. C6 ~ I2 5 }
7. This kind of drill requires good rigidity of the machine tool, especially the bearing accuracy of the machine tool spindle and the rotary accuracy of the drill clamp must be high. So it is generally used in CNC machine tools or machining centers. German companies Bilz, Hertel, Guehring and ILIX first introduced this kind of drill bit, followed by Japanese company Gao Ling Precision Machinery ... What is the Bilz specification? 4 ~ 4~20mm, Hertel called TF bit, its specification is? 3 ~ 20 mm, what is the specification of Greencool GS200? 3 ~ 20 mm (divided into left and right rotation directions). What are the specifications of ILIX? 2 ~16mm. (DFP
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2.2.2 S cemented carbide drill bit E%bjp9/:c
This kind of bit is called Delta-C bit in sandvik, Sweden, with a diameter of? 3 ~ 12.7mm； Japan Minefield Co., Ltd. is called Diget bit, and Hertel in Germany is called SE bit. What is the diameter range? 3 ~ 20mm. The characteristics of this drill are that the transverse edge is shortened after grinding and the axial force is reduced by 50%. The rake angle near the drill core is positive, so the cutting is sharp; The groove shape is parabolic, with large core thickness and strong rigidity; There are two oil injection cooling holes, which have good cooling conditions; The circular cutting edge and chip removal groove are arranged reasonably, which is convenient for the chip to be broken into small pieces and discharged smoothly. Suitable for processing difficult-to-machine materials, high-temperature alloys, Inconel alloy materials, etc. The commonly used drilling depth is 3.5D, the machining accuracy of the drill is IT9, and the roughness is Ra 1 ~ 2 microns ... When in use, the concentricity between the center of the drill and the spindle of the machine tool should not be greater than 0.03 microns ... Because of its high speed, it will generate a lot of heat and should be fully cooled. es-Kr。 & ampL
2.2.3 strong cemented carbide bit ts_v, k0
Sumitomo Electric Company of Japan and Mitsubishi Metal Company both produce this kind of drill bit. The former is called マルチ drill, and the latter is called リツチカド drill. What are the specifications? 4 ~18mm. There are two types: standard type and short type. The standard type is suitable for machining holes with depth of 3D ~ 4D, and the short type is suitable for machining holes with depth of1.5d. Can this drill be used as an auxiliary tool between indexable drill and welding drill? Instead of high-speed steel twist drill, the strength of the drill depends on the thickness of the core and the ratio of groove to back. The core thickness of standard twist drill is 15% ~ 23% of the diameter, and the groove-back ratio is (1 ~ 1.3): 1, while the core thickness of powerful drill is 30% of the diameter, and the groove-back ratio is 0.5: 1, so the cross-sectional area. In addition, due to the control of the chisel edge, the chisel edge of the drill bit is almost zero, and the central part has a rake angle. In order to further reduce the cutting force, the cutting edge is made into an arc edge with positive radial rake angle and almost constant torque. The circular cutting edge is well matched with the drilling groove, which makes the chips in a small arc shape, easy to break and smooth to discharge, but hard alloy materials with high wear resistance and strength must be used. The productivity of this drill is 3 ~ 5 times that of high speed steel twist drill. The smaller the diameter, the greater the improvement, while the diameter is less than? 16mm, the effect is more obvious. However, the symmetry of the cutting edge should be strictly controlled at 0.02mm, and the machining accuracy of the hole is: the expansion is not more than 30? M, the surface roughness of steel and cast iron is ra25 ~ 40? M, the service life is 10 times that of high-speed steel bit. R Ax|WI$4}
2.2.4 Welded carbide drill bit without chisel edge 0{qa8%t
This product produced by Japan's Mitsubishi Metal Co., Ltd. and Qifu Metal Co., Ltd. is called a new drill tip drill. What are the specifications? 9.5 ~ 30.5 mm, used for processing holes with a hole depth of less than 5D. This kind of drill is characterized by low axial force, productivity 5 ~ 10 times higher than that of high-speed steel drill, cutting speed 6 times higher than that of high-speed steel, feed speed10.5 times, and reaming less than 40? M. When the feed speed is greater than 0.2 mm/r, the chips are finer. Comparing the new drill with other drills with cemented carbide blades, it can be observed that when the hardness of the workpiece increases, the average axial thrust and spindle power of the new drill increase less than those of other drills with cemented carbide blades. When the hardness of the workpiece increases from 66HRB to 104HRB, the average axial thrust of the new bit increases by 25%, while that of other bits with cemented carbide inserts increases by 63% ~ 97%. 2.3 Indexable cemented carbide bit =m\f
Indexable cemented carbide bits are popular in the world, and each country has its own advantages in structural form and blade shape. Most of it is used? About 16 ~ 170 mm, the hole depth of cutting is mostly less than 3D (shallow hole drilling), especially as high as 8D (deep hole drilling). The efficiency of this drill is 3 ~ 10 times higher than that of twist drill, and the cutting speed after TiC coating can reach 300m/min. Recently, for large-size indexable cemented carbide drill bits, the cutter pad type has been developed, so that the cutter body can be used many times, represented by Hertel, Walter, Komet, Bilz and Sandvik in Sweden. sbMW6Rxu+
2.3. 1 cemented carbide indexable shallow hole drill 0UUR! }2c
Diameter greater than? 12mm holes with a depth less than 3D are widely used to make cemented carbide indexable insert shallow hole drills in the world. This kind of drill bit not only has high cutting performance, but also does not need to grind the drill tip again. As long as the blade is replaced, the bit body can be used for a long time. Therefore, it is very popular and becomes a common drill bit in CNC drilling machines and machining centers. There is no need to pre-drill the center hole on the workpiece before drilling, so it has self-centering ability. What is the size range of t- Ma Xu shallow hole drill provided by sandvik Company in Sweden? 17.5 ~ 58 mm. Drill-Fix short-hole drill provided by Hertel company in Germany, what is its size range? 16 ~ 82mm； The ABS-KUB short-hole drill provided by KOMET company in Germany can be extended to? 12~82; WIDAXBW shallow hole drill provided by Germany WIDIA Company can be extended to? 12 ~ 105 mm, the shallow hole drills of three German companies are all equipped with coolant injection holes, and the chip grooves of Hertel and KOMET companies are spiral, which is very beneficial to chip removal. This kind of drill has high metal removal rate, the drilling speed of ordinary carbon steel reaches 120 ~ 150 m/min, and it has high rigidity. In addition, WIDIA Germany also provides indexable shallow hole trepanning drills (generally, the maximum hole depth is 3D, especially 5D). What is the size range? 65 ~ 400 mm q'3K6y~y
There are 8 kinds of TDJ TAC shallow-hole drills produced by Toshiba Tungsten Industry Co., Ltd. in Japan, which can be used to process holes with diameters less than? What is the diameter of drill pipe for holes with a depth less than 2D 18mm? 25mm. Its structure is machine-clamped indexable, with two cutting edges, an inner edge and an outer edge. bit