Training guide
Yantai Nanshan College Mechanical Engineering Training Center
Metallurgy Teaching and Research Room
Training a basic operation of the lathe
I. The purpose of the training:
1. To understand the safety operation regulations of ordinary lathe
2. To master the basic operation of ordinary lathe and the steps
3. The relevant requirements for the operator
4. To master the basic operation skills in turning processing
5. To cultivate a good work ethic
II. Practical training content:
1. Safety technology
2. Familiar with the structural composition and function of ordinary lathe
3. Familiar with the basic operation of ordinary lathe
①Starting and stopping the lathe
②The lathe speed, feed, feed direction, light screw conversion
3. The lathe manual feed control
three. Training equipment:
C616-1D lathe 18 sets
Four. Practical training steps:
(a) familiar with the basic concept of turning and its processing range
Turning is the use of the workpiece on the lathe rotary motion and tool movement to change the shape and size of the blank, machining it into the required parts of a cutting processing method. Where the rotation of the workpiece is the main motion and the movement of the tool is the feed motion (Figure 1-1).
Figure 1-1 turning movement lathe is mainly used for processing the surface of the rotating body (Figure 1-2), the processing of the dimensional tolerance level of IT11 ~ IT6, the surface roughness Ra value of 12.5 ~ 0.8 μm. There are many types of lathes, which horizontal lathe
The most widely used.
Figure 1-2 Typical surfaces that can be processed by ordinary lathes
a) Turning the outer garden b) Turning the end face C) Turning the taper d) Cutting grooves, cut off e) Cutting the inner groove f) Drilling the center hole
g) Drilling h) Boring i) Reaming j) Turning the forming surface k) Turning the external threads l) Knurling
(ii) Learning the model of the horizontal lathe and the structure of the composition of the < /p>
Ⅰ, the model of the machine
C 6 1 32
Main parameter code (1/10 of the maximum turning diameter, that is, 320mm)
Machine tool type code (ordinary lathe type)
Machine tool group code (ordinary lathe group)
Machine tool type code (lathe category)
C 6 16
1/10 of the main parameter, i.e., the dimension from the lathe spindle axis to the guideway surface is 160mm,
(the maximum diameter of its turning workpiece is 320mm).
Group (ordinary lathe)
Category (lathe class)
Ⅱ, the structure of the horizontal lathe
1. Horizontal lathe model
Horizontal lathe with C61 × × × × to indicate, where C for the machine tool classification number, indicating the lathe class machine tools; 61 for the group system code, indicating horizontal. Other relevant parameters of the lathe and the improvement of the number.
2. The name and use of each part of the horizontal lathe
The shape of C6132 ordinary lathe is shown in Fig. 1-3.
Figure 1-3 C6132 general lathe
1-head box; 2-feed box; 3-gearbox; 4-front foot; 5-skateboard box; 6-tool holder; 7 - tailstock; 8-screw; 9-optical bar; 10-bed; 11-rear foot; 12-middle tool holder; 13-square tool holder; 14-rotary table; 15-small tool holder; 16-large tool holder
1. spindle box, also known as the head box, containing the spindle and speed change mechanism. Variable speed is by changing the position of the handle located outside the headstock box, the spindle can be made to obtain 12 different rotational speeds (45 ~ 1980 r/min). The spindle is hollow and can pass long bars, the maximum diameter of the bar that can pass through the hole of the spindle is 29 mm. the right end of the spindle has an external thread for connecting chucks, dials and other accessories. The inner surface of the right end of the spindle is a taper hole of Moh's No. 5, which can be inserted into the taper sleeve and the top of the spindle.When the top of the spindle is used and the top of the spindle is used simultaneously with the top of the tailstock to install the shaft workpieces, the maximum distance between the two tops of the spindle is 750mm.The headstock box plays another important role in transmitting the movement to the feed box, and it can change the direction of the feed.
2. feed box also known as the tool box, it is the feed movement of the variable speed mechanism. It is fixed in the lower part of the head box on the front side of the bed. Change the position of the handle outside the feed box, the spindle in the head box can be passed down to the movement of the output of the feed box for the light bar or screw to obtain different speeds, in order to change the size of the amount of feed or turning threads of different pitches. Its longitudinal feed is 0.06-0.83mm/r; transverse feed is 0.04-0.78mm/r; it can turn 17 kinds of metric threads (pitch 0.5-9mm) and 32 kinds of imperial threads (2-38 teeth per inch).
3. The gearbox is mounted in the inner cavity of the front foot of the lathe and is driven directly by the motor through the coupling to the gear shaft in the gearbox. There are two long handles outside the gearbox to move the double and triple slip gears on the drive shaft respectively, which can **** get 6 kinds of speeds and drive to the headstock box through the belt.
4. sliding plate box Also known as drag plate box, sliding plate box is the feed movement of the manipulation mechanism. It makes the rotary movement of the light bar or screw, through the gear and rack or screw and open and close the nut, push the lathe for feeding movement. There are three layers of sliding plate on the sliding plate box, when connected to the light bar, it can make the bed saddle drive the middle sliding plate, small sliding plate and tool holder to move longitudinally along the bed rail; the middle sliding plate can drive the small sliding plate and the tool holder to move transversally along the bed saddle on the guide rail. Therefore, the tool holder can make longitudinal or transverse linear feeding movement. Threads can be turned when the screw is connected and the opening and closing nuts are closed. The skateboard box is equipped with an interlocking mechanism so that the light bar and the screw cannot be used at the same time.
5. Tool holder It is used to clamp the turning tool, and can be used for longitudinal, transverse and oblique movement. Tool holder is a multi-layer structure, it consists of the following components. (See Figure 1-4)
1) bed saddle It is firmly connected with the sliding plate box, can be moved longitudinally along the bed rail.
(2) Center skateboard It is installed on the transverse rail on the top surface of the bed saddle and can be moved transversely.
(3) Turntable It is fixed on the center slide plate, and after loosening the fastening nut, the turntable can be rotated to make it and the bed guide rail into a desired angle, and then the nut can be tightened to process the conical surface and so on.
(4) small slide plate It is installed in the dovetail groove above the turntable, and can be used for short-distance feeding movement.
(5) square tool holder It is fixed on the small slide plate, and can clamp four turning tools at the same time. By loosening the locking handle, the square tool holder can be turned to change the required turning tools to the working position.
6. Tailstock It is used to mount the rear center to support longer workpiece for machining, or to mount tools such as drills and reamers for hole machining. Offset tailstock can turn long workpiece cones. The structure of the tailstock consists of the following parts. (See Figs. 1-5)
(1) Sleeve Its left end has a tapered hole for mounting a center or taper shank tool. The axial position of the sleeve in the body of the tailstock can be adjusted by the handwheel and fixed by the locking handle. When the sleeve is backed to the extreme right position, the center or tool can be removed.
(2) tailstock body It is connected with the base, when loosening the fixing screw, twisting the screw can make the tailstock body in the base plate for trace lateral movement, in order to make the front and rear of the top of the center or offset a certain distance turning long taper.
3) Base It is mounted directly on the bed guide rail to support the tailstock body.
7. Light bar and screw Transmit the motion of the feed box to the slide box. The light bar is used for general turning and the screw is used for thread turning.
8. Bed It is the basic part of lathe, used to connect the main parts and ensure the correct relative position of each part in the movement. There are guide rails on the bed for the movement of the slide box and tailstock.
9 Joystick Joystick is the control mechanism of the lathe, the left end of the joystick and the right side of the drag plate box are equipped with a handle, the operator can easily manipulate the handle to control the lathe spindle forward, reverse or stop.
10 Joystick The joystick is the control mechanism of the lathe, and there is a handle at the left end of the joystick and at the right side of the drag box, and the operator can easily manipulate the handle to control the lathe spindle to turn forward, reverse or stop.
Figure 1-4 Tool holder
Figure 1-5 Tailstock
1 Top 2 Sleeve Locking Handle 3 Top Sleeve 4 Screw 5 Nut 6 Tailstock Locking Handle 7 Hand Wheel 8 Tailstock Body 9 Base
(C) Transmission System of Horizontal Lathe
Power output from the electric motor is transmitted through the gearbox by the belt drive to the spindle, and the position of the handle is changed to obtain different positions of the gearbox and outside the spindle box. Changing the position of the gearbox and the handle outside the spindle box, different gear sets are meshed, thus obtaining different spindle speeds. The spindle drives the workpiece through the chuck for rotary motion. At the same time, the rotary motion of the spindle through the reversing mechanism, exchange gear, feed box, light bar (or screw) to the sliding plate box, so that the sliding plate box to drive the tool holder along the bed for linear feeding movement.
(D) Various handles and basic operation of horizontal lathe
1. Adjustment of horizontal lathe and use of handles
The adjustment of C6132 lathe is mainly carried out by changing the position of the respective handles, see Fig. 1-6 for details.
Fig. 1-6 Adjustment handles of C6132 lathe
1, 2, 6 -Main motion speed change handle 3,4-Feeding motion speed change handle 5-Commutation handle for left and right movement of tool holder 7-Traverse manual handle for tool holder 8-Square tool holder locking handle 9-Small tool holder Move handle 10-Tailstock sleeve locking handle 11-Tailstock locking handle 12-Tailstock sleeve moving handwheel 13-Spindle forward and reverse and stop handle 14-"Open and close the nut "Opening and closing handle 15-Tool holder transverse automatic handle 16-Tool holder longitudinal automatic handle 17-Tool holder longitudinal manual handwheel 18-Light bar, screw replacement of the use of the clutch
2. Horizontal lathe's Basic operation
(1) Stopping practice (spindle forward and reverse and stop handle 13 in the stop position)
1) Correctly change the spindle speed. Variable speed change handle 1, 2 or 6 on the outside of the gearbox and spindle box can get various corresponding spindle speeds. When the handle is not smoothly dialed, use your hand to slightly rotate the chuck.
2) Correctly change the feed amount. According to the selected amount of feed to see the feed box on the label, and then according to the label on the feed change handle position to change the position of handle 3 and 4, that is, to get the selected amount of feed.
3) Familiarize yourself with the direction of rotation of the longitudinal and transverse manual feed handles. The left hand holds the longitudinal feeding manual handwheel 17, and the right hand holds the transverse feeding manual handle 7. rotate the handwheel clockwise and counterclockwise respectively to manipulate the direction of movement of the tool holder and the skateboard box.
4) Familiarize yourself with the operation of longitudinal or transverse motorized feeding. The light bar or screw connecting handle 18 is located in the light bar connecting position, the longitudinal motorized feeding handle 16 can be lifted to longitudinal feeding, such as the transverse motorized feeding handle 15 can be lifted upward to transverse motorized feeding. The longitudinal and transverse motorized feeding can be stopped by triggering downward respectively.
5) operation of the tailstock. The tailstock is moved manually and fixed by fastening bolts and nuts. Turn the tailstock to move the sleeve handwheel 12, can make the sleeve in the tailstock movement, turn the tailstock locking handle 11, can be fixed in the tailstock sleeve.
(2) Low-speed driving practice Before practicing, you should check whether the position of each handle is in the correct position, and drive practice after no error.
1) Spindle start -- Motor start -- Manipulate spindle rotation -- Stop spindle rotation - -Shut down the motor
2) motorized feed - motor start - manipulate the spindle rotation - manual longitudinal and transverse feeding --Motorized longitudinal and transverse feed --Manual return --Motorized transverse feed --Manual return --Stop spindle rotation --Shut down the motor
Special note:
1) machine has not been completely stopped is strictly prohibited to change the spindle speed, otherwise serious spindle box gear tooth phenomenon or even machine accidents. Before driving to check whether the handle is in the correct position.
2) longitudinal and transverse handle in and out of the direction can not be shaken wrong, especially fast in and out of the knife to pay attention to, otherwise the workpiece will be scrapped and safety accidents.
3) transverse feed manual handle every turn of a frame, the tool transverse eat 0.02mm, its cylinder diameter cutting amount of 0.04mm.
V. Review thinking questions
1. turning process, the workpiece and tool need to make what movement? What are the names, symbols and units of turning elements? Explain the meaning of C6132A.
2. What are the main components of a horizontal lathe? What is the function of each?
3. What are the characteristics of the structure of a horizontal lathe? What are the main applications
Practical Training II Basic Turning Operations
I. Training Objectives:
1. To master the types, composition and basic angles of tools
2. To master the cutting methods of end face, external circle, etc.
3. To master the basic operation skills in turning processing
II. Practical training content:
1. Safe operation
2. Structure, types, basic angle and function of tools
3. Basic cutting operation of ordinary lathe
① Clamping of parts
② Installation of cutting tools
3. Turning methods of end face and external circle
④ Turning methods of knurling
⑤ Turning method of grooving and cutting
⑥Turning method of taper
III. Training equipment:
C616-1D lathe 18 sets
Four. Practical training steps:
(A) turning tool
Ⅰ, tool materials
1, tool materials should have the performance
(1) high hardness and good wear resistance. The hardness of the tool material must be higher than the hardness of the material to be processed in order to cut the metal. The general hardness of the tool material should be above 60HRC. The harder the tool material, the better its wear resistance.
(2) Sufficient strength and impact toughness. Strength refers to the role of cutting force, does not occur under the knife edge crumbling and the knife shaft broken with the performance. Impact toughness refers to the tool material in the impact or intermittent cutting conditions, to ensure that the ability not to collapse.
(3) high heat resistance. Heat resistance, also known as red hardness, is a measure of the performance of the tool material is the main indicator, it reflects the tool material at high temperatures can still maintain a high degree of hardness, abrasion resistance, strength, oxidation resistance, resistance to bonding and resistance to diffusion of the ability.
(4) good workmanship and economy
2, commonly used cutting tool materials
At present, the turning tool is widely used carbide cutting tool materials, in some cases also apply high-speed steel cutting tool materials.
(1) high-speed steel high-speed steel is a high-alloy steel, commonly known as white steel, sharp steel, wind steel, etc.. Its strength, impact toughness, processability is very good, is the manufacture of complex shapes of the main material of the tool. Such as: forming lathe, twist drill, milling cutter, gear cutting tools, etc.. High-speed steel heat resistance is not high, about 640 ℃ about its hardness decline, can not carry out high-speed cutting.
(2) Cemented carbide to heat-resistant and wear-resistant carbide, cobalt as a binder, the use of powder metallurgy method of pressing into various shapes of the blade, and then welded in the cutter head with copper brazing method as cutting tool materials. Cemented carbide wear resistance and hardness is much higher than high-speed steel, but plasticity and impact toughness is not as high as high-speed steel.
II, turning tool composition and turning angle
The turning tool is the shape of the simplest single-edged tool, a variety of other complex tools can be regarded as a combination of the turning tool and the evolution of the angle of the definition of the turning tool, are applicable to other tools.
1, the composition of the lathe
The lathe is composed of a cutter head (cutting part) and the body (clamping part). The cutting part of the tool is composed of three sides, two edges, a tip, that is, one point, two lines and three sides. (Figure 2-1)
(a) (b) (c)
2, the angle of the tool
The main angles of the tool are the front angle, the back angle, the main angle of deviation, the secondary angle of deviation, and tilt angle
1) Front Angle Angle between the front face of the tool and the base surface, indicating the degree of inclination of the front face. The front angle can be divided into positive, negative, zero, the front face of the knife in the base surface below the front angle is positive, and vice versa for the negative value, the phase overlap is zero.
The role of the front angle: increase the front angle, can make the cutting edge sharp, cutting force reduction, cutting temperature is low, tool wear is small, the surface processing quality is high. However, too large a rake angle will reduce the strength of the cutting edge and easily cause damage to the edge.
Selection principle: with carbide turning tool processing steel parts (plastic materials, etc.), generally selected = 10?~20 °; processing gray cast iron (brittle materials, etc.), generally selected = 5o ~ 15 °. Finishing, can take a larger front angle, roughing should take a smaller front angle. When the strength and hardness of the workpiece material is large, the front angle to take a smaller value, and sometimes even take a negative value.
2) rear angle The angle between the main rear face and the cutting plane, indicating the degree of inclination of the main rear face.
The role of the back angle: to reduce the friction between the main back face and the workpiece, and affect the strength and sharpness of the edge. Selection principle: the general back angle can be taken = 6?~8?
3) Main offset angle The angle between the main cutting edge and the projection of the feed direction on the base surface.
The role of the main offset angle: affect the working length of the cutting edge, cutting depth resistance, tip strength and heat dissipation conditions. The smaller the main deflection angle, the longer the cutting edge working length, the better the heat dissipation conditions, but the greater the depth of cut resistance.
Principle of selection: the main offset angle commonly used in turning tools are 45 °, 60 °, 75 °, 90 ° several. When the workpiece is thick and rigid, the smaller value can be taken. When turning long and thin shaft, in order to reduce the radial force caused by the workpiece bending deformation, it is appropriate to choose a larger value.
4) sub-deviation angle sub cutting edge and feed direction in the base surface projection between the angle.
Role: affect the surface roughness of the processed surface, reduce the sub-deviation angle can make the processed surface clean.
Selection principle: generally take = 5o ~ 15 °, fine turning can take 5o ~ 10 °, rough turning take 10o ~ 15 °.
5) edge inclination angle between the main cutting edge and the base surface of the angle between the tip of the cutting edge for the highest point of the cutting edge is positive, and vice versa for the negative value.
The role of camber: mainly affect the strength of the main cutting edge and control the direction of chip flow. Taking the bottom surface of the toolbar as the reference, when the tip of the toolbar is the highest point of the main cutting edge, it is positive, and the chips flow to the surface to be machined; when the main cutting edge is parallel to the bottom surface of the toolbar, it is =0o, and the chips flow in the direction perpendicular to the main cutting edge; when the tip of the toolbar is the lowest point of the main cutting edge, it is negative, and the chips flow to the surface that has been machined.
Selection principle: generally between 0o ~ ±5°. Roughing, often take a negative value, although the chip flow to the machined surface is no harm, but to ensure the strength of the main cutting edge is good. Finishing often take a positive value, so that the chip flow to the surface to be machined, so as not to scratch the quality of the surface to be machined.
Ⅲ, turning tool installation
The tool must be correctly and firmly installed in the tool holder, as shown in Figure 2-3.
Installation of the tool should pay attention to the following points:
1) the tool head should not extend too long, or cutting vibration, affecting the workpiece machining accuracy and surface roughness. Generally, the length of the cutter head extends no more than twice the thickness of the cutter bar, can see the tip of the cutter can be turned.
2) The tip of the tool should be as high as the centerline of the lathe spindle. Turning tool mounted too high, the rear angle decreases, the main back of the tool will produce strong friction with the workpiece; if mounted too low, the front angle decreases, cutting is not smooth, will make the tip of the tool chipped. The height of the tip of the tool can be adjusted according to the height of the top of the tailstock. Turning tool installation is shown in Figure 2-3a).
Figure 2-3 Turning tool installation a) Correct b) Incorrect
3) The shims on the bottom of the turning tool should be flat and as thick as possible to minimize the number of shims. After adjusting the tip height, tighten the lathe with at least two screws alternately.
(2) Turning outer circle, end face and step
Ⅰ, three-jaw self-centering chuck mounting workpiece
1. Mounting workpiece with three-jaw self-centering chuck
Figure 2-4 Structure of three-jaw self-centering chuck and mounting of workpiece
Three-jaw self-centering chuck structure is shown in Fig. 2-4a, when the small bevel gear is turned with the chuck wrench, the large bevel gear is also turned. When the small bevel gear is rotated with the chuck wrench, the large bevel gear is also rotated, and under the action of the plane threads on the back of the large bevel gear, the three jaws are moved centripetally or withdrawn at the same time, so as to clamp or loosen the workpiece. It is characterized by good centering and the accuracy of automatic centering can reach 0.05~0.15㎜. It can be used to clamp workpieces with small diameters, as shown in Figure 2-4b. Three counter jaws can be used when clamping cylindrical workpieces with larger diameters, as shown in Figure 2-4c. But three-jaw self-centering chuck because the clamping force is not large, so generally only suitable for lighter weight workpiece, when the weight of the workpiece for clamping, it is appropriate to use four-jaw single-action chuck or other special fixtures.
2. With a clip a top installation of the workpiece
For the general shorter rotary body type workpiece, more suitable for three-jaw self-centering chuck clamping, but for longer rotary body type workpiece, with this method is less rigid. Therefore, the general longer workpieces, especially the more important workpieces, can not be directly with three-jaw self-centering chuck clamping, but to use one end of the clamping, the other end of the clamping method with the top of the top of the back.
Ⅱ, turning cylindrical
1. Adjustment of the lathe
The adjustment of the lathe includes the spindle speed and the feed of the lathe tool.
The spindle speed is selected according to the cutting speed calculation. And the selection of cutting speed is related to the workpiece material, tool material and workpiece machining accuracy. Turning with high-speed steel cutter, V = 0.3 ~ 1m / s, with carbide cutter, V = 1 ~ 3m / s. Turning high hardness steel than turning low hardness steel speed is lower.
For example, with carbide tool machining diameter D = 200 mm cast iron pulley, selected cutting speed V = 0.9 m / s, calculate the spindle speed:
(rpm)
Feed is determined according to the requirements of the workpiece processing. Rough turning, generally take 0.2 ~ 0.3 mm / turn; fine turning, with the required surface roughness. For example, the surface roughness of Ra3.2, choose 0.1 ~ 0.2 mm / turn; Ra1.6, choose 0.06 ~ 0.12 mm / turn, and so on. Adjustment of the feed can be adjusted against the lathe feed table trigger handle position, the specific method is similar to adjust the spindle speed.
2. Rough turning and fine turning
The purpose of rough turning is to cut off the excess metal layer as soon as possible, so that the workpiece is close to the final shape and size. Rough turning should leave 0.5 ~ 1 mm machining allowance.
Finish turning is to cut off the remaining small amount of metal layer to obtain the required accuracy and surface roughness of the parts, so the back draft is smaller, about 0.1 ~ 0.2 mm, cutting speed can be used for higher or lower speed, beginners can use lower speed. In order to improve the surface roughness of the workpiece, used for fine turning of the lathe tool's front and back tool surface should be used oil stone plus machine oil grinding, sometimes the tip of the tool is ground into a small arc.
In order to ensure the dimensional accuracy of machining, the trial cut method of turning should be used. The steps of the test-cutting method are shown in Figure 2-5.
Figure 2-5 Steps of trial cutting
3. Quality analysis of turning cylindrical
1) Incorrect size: the reason is that the turning is careless, misreading the size; the dial is calculated incorrectly or the operation is incorrect; the measurement is not careful, inaccurate and caused.
2) surface roughness is not and requirements: the reason is the lathe tool sharpening angle is not correct; tool installation is not correct or tool wear, as well as cutting dosage selection is not appropriate; lathe parts of the gap is too large and caused.
3) taper of the outer diameter: the reason is that the depth of the tool is too large, tool wear; tool or drag plate loosening; turning with a small drag plate under the turntable datum line is not aligned with the "0" line; the two top turning bed end "0" line is not in the axis of the line; finishing turning machining allowance is insufficient.
Ⅲ, turning end face
End face turning method: turning end face, the main cutting edge of the tool to have a certain angle with the end face. Workpiece out of the chuck part should be as short as possible, turning with the drag plate transverse tool, the number of times according to the machining allowance, can be used from the outside to the center of the tool, can also be used from the center of the circle to the outside of the tool method.
Commonly used end face turning in several cases as shown in Figure 2-6.
Figure 2-6 Turning face of the common turning tool
Turning face should pay attention to the following points:
1) the tip of the tool should be aligned with the center of the workpiece, so as not to turn out the center of the end of the face to avoid leaving a convex platform.
2) Offsetting the tool to turn the end face, when the back draft is large, it is easy to tie the knife. Back eating amount ap selection: rough turning ap = 0.2 mm ~ 1 mm, fine turning ap = 0.05 mm ~ 0.2 mm.
3) the diameter of the end face from the outside to the center of the change, the cutting speed is also changing in the calculation of cutting speed must be calculated according to the maximum diameter of the end face.
4) Turning a larger diameter of the end face, if there is a concave center or convex belly, you should check the turning tool and square tool holder, as well as the large drag plate is locked.
Turning end face quality analysis:
1) the end face is not flat, resulting in the phenomenon of convex and concave or the center of the end face to leave a "small head"; the reason for when the lathe tool sharpening or installation is not correct, the tip of the tool is not aligned with the center of the workpiece, the depth of the late is too large, the lathe has a gap caused by the movement of the drag plate.
2) poor surface roughness. The reason is that the lathe tool is not sharp, manual tool swing unevenly or too fast, automatic tool cutting dosage selection is not appropriate
Ⅳ, turning steps
Turning steps of the method of turning and turning cylindrical basically the same, but in the turning should take into account the diameter of the outer circle and the length of the steps of the two directions of the size requirements, but also to ensure that the perpendicularity between the step plane and the axis of the workpiece requirements.
Step length size control methods:
1) step length size requirements are low when you can directly use the large drag plate dial control.
2) The step length can be used to determine the position with a steel straightedge or sample plate, as shown in Figure 2-7a and 2-7b. Turning with the tip of the first slightly shorter than the step length of the indentation as the machining boundary, the exact length of the step can be measured with a vernier caliper or depth vernier caliper.
Figure 2-7 Control method of step length size
3) When the step length size is required to be higher and shorter, a small slide dial can be used to control its length.
(C) knurling
There are two kinds of patterns: straight and anilox, and knurling knives are divided into straight knurling knives (Fig. 2-8a) and anilox knurling knives (Fig. 2-8b, c). Knurling is the use of knurling knives to extrude the workpiece, so that its surface produces plastic deformation and the formation of patterns. The radial compression force of knurling is high, so the workpiece speed should be low during machining. Need to supply sufficient cooling lubricant, so as not to study the bad knurling knife and prevent the fine chips stagnation in the knurling knife and produce messy pattern.
Figure 2-8 knurling knife
(D) grooving, cutting
Ⅰ, grooving
in the surface of the workpiece on the car groove method is called grooving, the shape of the outer groove, the inner groove and the end of the groove. Such as Figure 2-9.
Figure 2-9 commonly used method of grooving Figure 2-10 high-speed steel grooving knife
1. grooving knife selection
Often choose high-speed steel grooving knife grooving, grooving knife geometry and angle as shown in Figure 2-10.
2. grooving method
Turning precision is not high and narrow width of the rectangular groove, you can use the knife width is equal to the width of the groove grooving knife, using a straight method of turning out. Higher precision requirements, generally divided into two turning.
Turning wider grooves, can be used several times straight into the method of cutting (see Figure 2-11), and on both sides of the groove to leave a certain amount of fine-turning allowance, and then according to the depth of the groove, the width of the groove fine-turning to size.
Figure 2-11 cut wide groove
II, cut off
Cut off with a cutter. Cut off the shape of the knife is similar to the groove cutter, but because the cutter head is narrow and long, it is easy to break. Commonly used method of cutting off the straight into the method and the left and right to borrow two kinds of knife method, as shown in Figure 2-11. Straight into the method is commonly used to cut off the cast iron and other brittle materials; left and right to borrow the knife method is commonly used to cut off the steel and other plastic materials.
Cut off should pay attention to the following points:
1) cut off generally on the chuck, as shown in Figure 2-12. The cut-off point of the workpiece should be closer to the chuck, avoid cutting off the workpiece mounted on the top.
Figure 2-12 Cutting on the chuck Figure 2-13 The tip of the cutting tool must be the same height as the center of the workpiece
2) The tip of the cutting tool must be the same height as the center of the workpiece, otherwise the cut-off will be left with a bump, and the head of the tool is easily damaged (Figure 2-13).
3) cut off the length of the knife out of the tool holder should not be too long, the feed should be slow and even. Will cut off, must slow down the feed speed, so as not to break the cutter head.
5) two top workpiece cut off, can not be cut directly to the center, in order to prevent the knife broken, the workpiece fly out
(E) turning conical surface
Turning the workpiece into a conical surface is called turning conical. Commonly used turning conical surface method has a wide knife method, rotating small tool holder method, against the mold method, tailstock offset method and so on. Here to introduce the rotation of small tool holder method, tailstock offset method.
Ⅰ, rotating small tool holder method
When processing the taper surface is not long workpiece, can be used to rotate the small tool holder method of turning. Turning, the small slide below the turntable on the nut loosening, turn the turntable to the desired cone half-angle α / 2 of the carat, aligned with the reference zero line, and then fix the turntable on the nut, if the taper angle is not an integer, can be estimated near the cone of a value, the test drive and then gradually to find the right, as shown in Figure 2-14.
Figure 2-14 Turning small slide turning cone Figure 2-15 Offset seat method turning cone
II, tailstock offset method
When turning small taper, taper part of the longer conical surface, you can use the offset tailstock method, this method can be automatic tool, the disadvantage is that it can not be turning the whole cone and the inner taper, as well as taper of the workpiece is larger. Offset the slide plate on the tailstock by a distance S, so that the two top lines after offsetting intersect the original two top center lines by an α/2 angle, and the offset of the tailstock depends on the machining position of the size of the workpiece head between the two tops. The offset of the tailstock is related to the total length of the workpiece, as shown in Figure 2-15, the tailstock offset can be calculated by the following formula:
where S - tailstock offset;
L - length of the cone part of the workpiece;
L0 - the total length of the workpiece;
D, d - cone big head diameter and cone small head diameter.
The offset direction of the bed end is determined by the direction of the cone of the workpiece. When the small end of the workpiece is close to the end of the bed, the end of the bed should move inward, and vice versa, the end of the bed should move outward.
The quality analysis of turning cone:
1. The taper is not accurate, the reason when the calculation error; small drag plate rotation angle and bed end offset offset is not accurate; or the turning tool, drag plate, bed end is not fixed, and it is caused by moving in the turning. Even because the surface roughness of the workpiece is too poor, the gauge or workpiece burrs or not wiped clean, resulting in errors in inspection and measurement.
3. Taper busbar is not straight, taper busbar is not straight, taper surface is not a straight line, the taper produces a concave-convex phenomenon or the middle of the low, high at both ends. The main reason is that the tool installation is not centered.
4. Surface roughness is not required, resulting in poor surface roughness is due to improper choice of cutting dosage, tool wear or sharpening angle is not right. The surface is not polished or the polishing margin is not enough. Turning taper with a small drag plate, manual tooling is not uniform, in addition to the clearance of the machine tool, poor workpiece rigidity will also affect the surface roughness of the workpiece.
V. Review questions
1. cylindrical turning tool five main labeling angle is how to define? What is the role of each?
2. What are the requirements for installing a turning tool?
3. What is the purpose of test cutting? Explain the steps of test cutting with the actual operation method.
4. What tools are commonly used for turning external surfaces? Why is it common to use a 90° offset tool for turning the foreign face of a long shaft?
5. machining cone which? What are the characteristics of each? Each suitable for what type of production?
6. groove cutter and cutter geometry what are the characteristics?