chapter 9 drilling methods and machines. (cutting tool applications).
Metal removal cutting Tool material metal removal methods machining of metal single point machining tool and Operation machine tool slotting and thread forming and planing hole making process drill bit and drilling operation drilling method and machine tool operation and machine expansion and tapping multi-point machining milling cutting tools and Operation milling methods and machine broaching and sawing grinding processes grinding wheels and Operation grinding methods and machine grinding and honing 9. 1 Introduction one of the most important and important tools in any metal processing workshop is a drilling rig or a drilling machine. Although the rig is mainly used for drilling, it is usually used for hole expansion, drilling, tapping, drilling and drilling. All rigs follow the same fundamentals. The spindle turns a manual or automatic advanced cutting tool into a workpiece mounted on a table or placed in a drill press vise. 9. Many types and sizes of rigs are used in manufacturing. They range in size from sensitive bits for simple bench mounted to large multi A spindle machine capable of driving many drill bits at the same time. The following illustration shows the schematic diagram of the standard vertical drilling machine and the schematic diagram of the turret Drilling machine. These and other types of drill bits, such as sensitive and radial drill bits, are described below. 9. 2. 1 Simple drill press, as shown below, may be floor- Install, or have a shorter main post and install it on the bench. The action of this machine is very simple. The table on the floor model can be lifted and rotated around the machine column. Spindle rotation, lifting, travel can be set 4 \"to 8\" gear to limit and adjust the depth. 9. 2. 2 The sensitive bit Press name \"sensitive\" is used to indicate that the feed is operated manually, and the spindle and bit are balanced so that the operator can \"feel\" the pressure required to cut efficiently. A table- The installed sensitive drill press is shown below. The bit Press has the same movement as the previous one, plus a telescopic screw for lifting the work table and sliding the bit. These two features allow for easier handling of parts at different heights. 9. 2. The radial bit for handling large and medium-sized castings, Welters or forgings is the ideal radial bit. The length of the arm of the spindle housing ride specifies their dimensions. This arm can be from 3 feet to 12 feet long. The column diameter of the support arm can be from 10 \"to 30 \". For very large work, the arm can be rotated 180 degrees and placed in the workshop. Machine operator dial in speed and feed, same as other drilling machines. Drilling can be either manual or electric. 9. 3 The rigid and precise rig structure of the rig components is essential for obtaining appropriate results using a variety of knives. This section discusses the structural features of sensitive rigs, as its features are common in most other rigs. Base: The base is the main supporting part of the machine. It is a heavy duty gray iron or cast iron casting with slots, used to support and maintain work that is too big for the table. Columns: round columns can be made of gray cast iron or cast iron from larger machines, and can also be made of steel pipes from smaller drilling machines. It supports the table and head of the drill. Machining the outer surface is an accurate way to align the spindle with the workbench. Table: you can adjust the columns of the table up or down to the appropriate height. It can also rotate around the post to the desired working position. Most workbenches have slots and holes for installing vises and other work to keep attachments. Some tables are half. Universal, which means they can rotate around the horizontal axis. Head: head holds spindle, goose brush, pulley, motor and feed mechanism. The V- The belt from the motor drives the pulley at the front of the head, which in turn drives the spindle. The spindle turns the drill bit. Change the speed on the step V pulley drive by changing the position of V-belt. Speed on variables The speed drive mechanism is changed by the hand wheel on the head. The spindle must rotate when doing so. Quill assembly: the spindle rotates inside the quill on the bearing. The feathers move vertically through the gear rack frame. The Quill Assembly makes it possible to feed in or remove the cutter from work. At the lower end of the spindle is the Morse taper hole or the threaded stub for the mounting Chuck. To drill larger holes, remove the drill chuck and install the Morse cone cutter. Size classification: size (capacity) The length of the rig is determined by all of the following features: * twice the distance from the center of the spindle to the inner surface of the column. * Maximum length of feather pen travel. * Size of Mohs cone in spindle. * Horsepower of the motor. 9. Drilling systems are usually automated and computer controlled. Speed, feed, and cutting depth are usually pre-setset. This system combines drilling operations with expansion, drilling, sinking, etc. Below is a 3- CNC drilling machine shaft. 9. 4. 1 multi- Spindle drilling this type of drilling can be done on a drilling machine by using special accessories. The spindle position is adjustable and the number of spindles can be from 2 to 8. Drill bit, articulated knife, chamfer, etc. , Can be used for spindle. The rotational speed and feed speed of all the spindles in a drill bit are the same, and the required horsepower is the sum of the power of all the cutting tools used. In this type of machine, a large number of holes can be drilled at a time. Several drill bits of different diameter can be used at the same time. 9. 4. 2 The economic method for steel drilling to perform several different operations on one workpiece is steel drilling, as shown below. This may include drilling holes of two or more dimensions, expansion holes, tapping holes, and drilling holes. The work is placed in a vise or a special fixture and it is easy to move from one spindle to the next along the steel table. The drill press usually runs continuously, so the operator can perform the required machining operation by simply lowering each spindle to a preset stop. 9. 4. 3 turret drill bits with six or eight spindles enable the operator to use a variety of knives, but the workpiece can only move a few inches depending on the hole spacing. Turret can be rotated (indexed) In either direction, then put it down by hand or automatically for cutting. Some turret rigs have a spindle with automatic hydraulic control. For quick production, speed, feed and cutting depth can be preset. These machines are also made with the entire operation controlled by a computer ,( CNC turret drill Therefore, the operator only needs to load and unload the parts as shown below. 9. 5 Groups of operations- In drilling operations, the most common three methods of workpiece retention are: Vises are widely used for workpieces with fixed dimensions and shapes, such as flat, square and rectangular workpieces. Parallels are usually used to support work and protect the vise from drilling. Vises should be clamped on the table of the drill press to prevent them from rotating during operation. Angular vises tilt the workpiece and provide a method of drilling at a certain angle without tilting the workbench. Corner plate: The corner plate supports the work of its edge. The corner plates precisely align the workpiece perpendicular to the surface of the table, and they usually have holes and slots to allow clamping to the table and keeping the workpiece. Drill fixture: drill fixture is a production tool for drilling a hole or several holes in a large number of the same parts. The drill clip has several functions. First of all, it is a work holding device that clamp the work firmly. Second, it positions the work in the right position for drilling. The third function of the drill fixture is to direct the drill bit to work. This is achieved by using a drill sleeve. 9. 5. 1 tool holding device some of the knives used for drilling can be held directly in the spindle hole of the machine. Others must be fixed with a drill chuck, sleeve or one of many tool fixtures. Drill Chuck: cutting tools with straight handles are usually placed in the drill chuck. The most common drill chuck uses a key to lock the tool. Sleeves: There are many taper shank cutting tools of different sizes. When using a cutting tool smaller than the spindle taper, the sleeve must be installed on the handle of the cutting tool. Socket: If the taper handle of the cutting tool is greater than the spindle taper, use the socket to reduce it to the correct size. 9. 6 Deep- The term \"deep hole drill\" originally refers to the depth of the hole with a diameter of more than five times. Today, deep- Drilling is a general term for short holes and deep hole processing methods. Deep- Drilling is the preferred method for drilling holes with a depth of more than 10 times the diameter, but due to the high metal content of this method The removal capacity and accuracy are also competitive for small holes twice the diameter. During the drilling process, it is important that the debris is broken and can be transported without disturbing and affecting the surface of the drill. In deep drilling, the following problems can be solved by developing three different systems, thus providing drilling fluid supply and chip Transportation Freely machined hole depth of more than 100 times in diameter. These three systems are called: The gun drill system, the shooting system (two-tube system) Single tube system (STS). Some tools used in deep- Drilling is shown below. Hyper Tool made the gun drill, and Sandvik made the indexable Tool. 9. 6. The 1 gun drill system uses the oldest principle to provide drilling fluid. The coolant is supplied through the pipe inside the drill bit and the coolant is delivered to the cutting edge and then through V- A chip chute along the shape of the outside of the drill bit. Due to the V- Groove, the cross section of the tube occupies 3/4 of its circumference. Below is the gun drill system and its components. The gun drill belongs to the pressurized coolant series of the hole making tool. Regardless of the hole depth, they are ideal for fast, precision machining. Generally speaking, the gun drill can keep the flatness of the hole within 0. 001\" per inch (IPI) Penetration even if the tool is rather dull. For most jobs, alloy steel can be cut from 500 \"to 1000\" with a gun drill before reprocessing\" It is necessary to sharpen. In aluminum, it may be 15,000 \"while in cast iron it is usually 2000 \". Depending on the diameter of the tool, the gun drill rarely runs at a feed rate of more than 0. Every revolution (003)IPR). This is very light compared to the twist drill feed, which usually starts at 0. 005 IPR to 0. 010 IPR. However, compared with high speed steel, the gun drill does use a relatively high speed (HSS)twist drilling. This is the reason for the high metal content. Removal rate related to process. In aluminum, the speed can be 600 surface feet per minute (SFPM) Steel from 400 SFPM to 450 SFPM. The speed and feed of the gun drill are based on the workpiece material and workshop conditions. Published charts provide a starting point only. On-the- Floor experiments are essential to determine the correct combination of maximum tool life. The main body of the gun drill body is usually made of a steel pipe of 4120 aircraft quality, after heat treatment, the temperature is between 35 and 40 Rc. Weld the 4140 steel drive to one end of the tube and weld the tip of the carbide tool to the other end. Figure 9. The 18 shows five different knife tip geometry, as well as various coolant hole positions. There are two body styles for multiple flute tools: grinding and curling. The former is a thick-walled tubular shaft with grooves. The latter is a thin-walled tubular shaft with grooves. The number of flutes depends on the material being cut. When drilling holes in materials that are prone to breaking into small pieces, such as cast iron, two Select the flute tool. On the other hand, for materials such as D2 tool steel, single- Flute design is preferred. In this case, the chip is often a string and a single The flute tool will minimize the chance of clogging when removed from the hole. Consider a curl Style Gun drill body with two grooves produced by swaging and traditional milling-Style Gun drill. The coolant holes in the Curl mechanism have irregular shapes, allowing to carry much larger coolant than the comparable holes in the traditional equivalent diameter tool body. In addition, the formed groove is much deeper than the grinding tool, because the wall thickness between the groove and the coolant hole does not have to be considered. These deeper grooves improve the chip. Disassembly efficiency of tools. Gun drill tip the traditional gun drill has a hole in the carbide tip under the cutting edge. Pressurized cutting fluid pumps holes through the body of the tool. Fluid service three- Purpose of folding: lubrication and cooling of cutting edges; It forces the chip to move backwards along the flute inside the tool; It helps to harden the handle of the tool. A new design has a hole at the top of the tool tip that can effectively guide the fluid to the cutting edge. Another hole is located in a regular position and helps to provide the chip removal function. With these two methods, the total flow rate of the cutting fluid has doubled Hole arrangement. More importantly, the design uses the same speed and feed speed to produce about half the chips of traditional gun drill sizes of the same diameter, so most materials avoid packing the chips along the tool handle. The most common knife tip material is C2 carbide, which is one of the hardness grades and is usually related to cast iron applications. Because excessive tool wear is a major problem when cutting steel, it is recommended to use a hard grade like C2, although C5 carbide is marked as a grade of steel processing in most textbooks. C5 carbide is an impact. Wear grade, not wear grade Resistance grade, therefore not suitable for the tip of the gun drill tool. C3 carbide is harder than C2 and used for some applications; However, more care must be taken when starting over Because it is easier to heat and check the cutting edge, it is necessary to sharp this material. Recently, in order to extend the tool life, coating such as titanium nitrogen has been applied on the gun drill tip. Physical Vapor Deposition (PVD) It is the only practical process for coating on precision tools such as gun drills, but the results are not encouraging. Different from coating The cvd coating of the carbide gun drill tip does not appear to form a good metallurgical bonding. The coating will fall off during metal cutting. Chemical vapor deposition (CVD) Metallurgical bonding will be formed between the coating and the carbide substrate, but the high heat required for the process will distort the tool. It is hoped that these problems will be resolved in the near future. 9. 6. The shooting system consists of drill bit, outer tube, inner tube, connector, sleeve and sealing sleeve. The drill bit is screwed to the drill pipe through four screws Start the square line. The inner tube is longer than the outer tube. The drill pipe and the inner pipe are connected to the connector through the sleeve and the sealing sleeve. For different diameter ranges, the sleeve and sealing sleeve must be replaced. Below is the injection system and its components. 9. 6. 3 Single tube system [STS] The single tube system is based on the supply of external cutting fluid and the transportation of internal chips. Usually, the drill bit is screwed on the drill pipe. The drilling fluid is supplied through the space between the drill pipe and the drill hole. Then, the cutting fluid is taken out with the chip through the drill pipe. The speed of cutting fluid is so high that the chip transport is carried out through the pipeline without interference. Since the chip evacuation is internal, there is no need for chip removal slots in the handle, so the tip crosses The sections can be completely rounded and provide higher rigidity than the gun drill system. The single tube system and its components are shown below. 9. 6. The comparison of 4 STS and ejection systems the single tube system and the ejection system have a wide range of applications, but sometimes one system is better than the other. STS are preferred in materials with poor chip formation performance, such as stainless steel, low When there is a problem of chip breakage, carbon steel and materials with uneven structure. STS is also more favorable for long production operation, uniform and super-long work pieces and hole diameter greater than 7. 875\". The jacking system does not require a seal between the workpiece and the drill sleeve. Therefore, the system can easily adapt to existing machines, which is better in CNC lathe, universal machine tool and machining center. Since the cutting fluid is supplied between the outer pipe and the inner pipe, there is no need for space between the drill pipe and the hole wall in the case of STS drilling. Therefore, in the workpiece where there may be a sealing problem, the top-out system is usually used for processing. When it is possible to guide using a pre-drilled rather than a drill Bush, for example in a machining center, the top-out system can be used to take advantage. Little George Schneider CMfgE honorary professor of engineering technology Lawrence University of Science and Technology pre-school chairman Detroit Chapter 1 former chairman of the Association of Manufacturing Engineers International Association of hard alloy and tools engineers Lawrence Institute of Technology. -www. ltu. Hall of Edou Prenticewww. prenhall.