Second, internship time: 2011.4.12-2012.4.25.
Third, the internship location: Tangshan High-tech Development Zone
Four. Internship unit and department: metalworking workshop of production department of Tanggang Tianlei Electric Machine Manufacturing Co., Ltd.
Verb (abbreviation of verb) Practice content:
Practical process
1, CNC lathe: Our first job is the operation of CNC lathe. It is programmed to control the lathe for machining. Through the operation and programming of CNC lathe, I deeply felt the convenience, accuracy and quickness of CNC. As long as the correct program is input, the lathe will perform the corresponding operation. The programming requirements of car counting are very high, and a wrong symbol may lead to the failure of car counting. Programming was not difficult for me, and I soon came up with a feasible scheme. Later, I learned CNC EDM, which also needs programming. But it is programmed automatically by the computer, as long as you input the graphics of the parts to be processed, choose the cutting path and put the raw materials away. That machine is so convenient, although there is no chance of actual operation, we are still amazed to see some cutting objects next to it. Those badges with good touch make us deeply impressed by the great power of science and technology!
2. Fitter: During the fitter's internship, we learned that the main contents of fitter are scraping, drilling, tapping, sawing, filing, assembling and marking; Understand the structure, classification, selection, filing posture, filing method and quality inspection of archives. First of all, we must get the right gear. It is the key to keep the file moving in a straight line when filing the plane. There are two kinds of filing force: horizontal thrust and vertical pressure. When pushing the file forward, the front hand pressure gradually decreases, and then it decreases when pushing the file to the middle position, and the pressure on both hands is the same. When pushing the file forward, the front hand pressure gradually decreases and then increases. No pressure is applied when the file is returned. This will make it easier for us to file. Then scrape, grind, drill, hinge, tap and so on.
3. Analysis of the processing technology of parts encountered in the internship: In the process analysis of part drawings, it is necessary to understand the technical requirements such as structural characteristics, accuracy, materials and heat treatment of parts, and learn product assembly drawings, parts assembly drawings and acceptance criteria. The general machining route of carburized parts is: blanking → forging → normalizing → rough machining → semi-finishing → carburizing → decarburization (for parts that do not need to improve hardness) → quenching → threading, drilling or milling → rough grinding → low temperature aging → semi-fine grinding → low temperature aging → fine grinding; Selection of rough datum: If there are any non-machined surfaces, the non-machined surfaces should be selected as the rough datum. For casting shafts with all surfaces to be machined, align them according to the surface with the minimum machining allowance. And choose a flat and smooth surface to avoid the gate. Choose a solid and reliable surface as the rough benchmark, and the rough benchmark cannot be reused. Selection of precision datum: In order to conform to the principle of datum coincidence, design datum or assembly datum should be selected as far as possible for positioning datum. In line with the principle of unified benchmarks. In most processes, try to use the same positioning datum. Make the positioning datum coincide with the measuring datum as much as possible. Select the surface with high precision and stable and reliable installation as the fine benchmark.
Threaded shaft: a typical case study of NC lathe machining programming (Siemens 802s CNC system) ⅰ. programming approach
There are two kinds of NC programming methods: manual programming and automatic programming. Manual programming refers to the programming process that is mainly completed by hand from part pattern analysis, data calculation, programming list, input program to program verification. It is suitable for point-to-point machining or machining parts with less complicated geometry, as well as occasions with simple calculation, few program segments and easy programming. However, for parts with complex geometric shapes (especially parts composed of spatial surfaces) and parts with uncomplicated geometric elements that need a lot of programming, automatic programming should be adopted because of the tedious work, heavy workload, easy mistakes and difficult program verification. The so-called automatic programming means that most or all of the programming work is completed by computers, which can effectively solve the processing problems of complex parts and is also the future development trend of NC programming. At the same time, we should also see that manual programming is the basis of automatic programming, and many core experiences of automatic programming come from manual programming, which complement each other.
Ⅱ. Programming steps
After you get the part drawing, you should first analyze the part drawing and determine the processing technology, that is, determine the processing method (such as fixture, clamping and positioning method, etc.). ), processing route (such as feed route, tool alignment point, tool change point, etc. ) and process parameters (such as feed speed, spindle speed, cutting speed and cutting depth, etc. ). Secondly, numerical calculation is needed. Most CNC systems have the tool compensation function, and only need to calculate the coordinate values of the intersection (or tangent point) of the adjacent geometric elements of the contour, and get the coordinate values of the starting point and ending point of each geometric element and the center of the arc. Finally, according to the calculated tool path coordinate values, the determined machining parameters and auxiliary actions, combined with the coordinate instruction code and program segment format specified by the numerical control system, the part machining program sheet is written segment by segment and input into the memory of the numerical control device.
Ⅲ. Analysis of typical cases
CNC lathes mainly process rotary parts, and the typical machining surfaces are nothing more than external cylindrical surface, external conical surface, thread, arc surface and groove. For example, it is more suitable to process parts with the shape shown in the figure by manual programming. Because different CNC systems have different programming instruction codes, they should be programmed according to the equipment type. Taking Siemens 802s CNC system as an example, the following operations are required.
(1) Determine the processing route
Determine the processing route according to the processing principle of "first main and then auxiliary, first fine and then coarse". Rough machining the outer contour with fixed cycle instruction, then finish machining, then turn the tool groove, and finally process the thread.
(2) Selection of clamping mode and cutting point
The three-jaw self-centering chuck is used for self-centering clamping, and the tool alignment point is selected at the intersection of the right end face of the workpiece and the rotating shaft.
(3) Select the cutter
According to the machining requirements, four cutters are selected, the number 1 is the rough cylindrical turning tool, the number 2 is the fine cylindrical turning tool, the number 3 is the grooving tool, and the number 4 is the threading tool. Align the cutter with trial cutting method and process the end face at the same time.
(4) determining cutting parameters
Turning the excircle, the spindle speed is 500 rpm in rough turning, the feed speed is 0.3 mm/min, the spindle speed is 800 rpm in finish turning, the feed speed is 0.08 mm/min, the spindle speed is 300 rpm in slotting and tapping, and the feed speed is 0. 1 mm/min.
(5) Programming practice report network
Determine the intersection point between the axis and the center of the ball head as the programming origin, and the machining procedure of the parts is as follows:
main program
jxcp 1.mpf
N05 g90 g95 g00 x80 z 100 (tool changing point)
N10t1d1m03s500m08 (cylindrical roughing tool)
-cname="l0 1 "
R105 =1r106 = 0.25r108 =1.5 (set the blank cutting cycle parameters).
r 109 = 7 r 1 10 = 2 r 1 1 1 = 0.3 r 1 12 = 0.08
N 15 lcyc95 (calling rough cutting cycle)
n20 g00 x80 z 100 m05 m09
n25 m00
N30T2D 1M03S80M08 (cylindrical finish turning tool)
N35 r 105=5 (setting blank cutting cycle parameters)
N40 lcyc95 (calling blank cutting cycle finishing)
n45 g00 x80 z 100 m05 m09
n50 m00
N55 t3d 1 m03 s300 m08 (slotted turning tool with width of 4mm)
n60 g00 x37 z-23
n65 g0 1 x26 f0. 1
n70 g0 1 x37
n75 g0 1 z-22
N80 g0 1 x25.8 internship report network
n85 g0 1 z-23
n90 g0 1 x37
n95 g00 x80 z 100 m05 m09
n 100 m00
N105t4d1m03s300m08 (triangular thread turning tool)
R100 = 29.8 r10/=-3r102 = 29.8 (set thread cutting cycle parameters)
r 103 =- 18 r 104 = 2 r 105 = 1 r 106 = 0. 1
r 109 = 4 r 1 10 = 2 r 1 1 1 = 1.24 r 1 12 = 0
r 1 13 = 5 r 1 14 = 1
N 1 10 lcyc97 (calling thread cutting cycle)
n 1 15 g00x 80 z 100 m05 m09
n 120 m00
N125t3d1M03S300M08 (cutting the turning tool, width 4mm)
n 130 g00 x45 z-60
n 135g 0 1x 0 f 0. 1
n 140 g00 X80 z 100 m05 m09
n 145 m02
subroutine
l0 1.spf
n05 g0 1x0 z 12
n 10 g03 x24 z0 cr= 12
n 15 g0 1 z-3
n20 g0 1 x25.8
n25 g0 1 x29.8 z-5
n30 g0 1 z-23
n35 g0 1 x33
n40 g0 1 x35 z-24
n45 g0 1 z-33
n50 g02 x 36.725 z-37.838 Cr = 14
n55 g0 1 x42 z-45
N60g0 1Z-60 internship report network
n65 g0 1 x45
n70 m 17
Machining experience: programming is the key to realize NC machining. Although this paper only analyzes a case of NC lathe machining parts through programming, it is representative. Because CNC lathes can process complex surfaces that ordinary lathes can't process, the machining accuracy is high, the quality is easy to ensure and the development prospect is very broad, so it is particularly important to master the machining programming technology of CNC lathes.
Sixth, the internship summary:
The internship that lasted nearly two weeks is over. This internship really touched the front line of machinery manufacturing industry, and learned about the development status and development trend of machinery manufacturing in China. In the new century, science and technology will develop at a faster speed and be more closely integrated into various fields, which will greatly broaden the development direction of machinery manufacturing.
Its development trend can be summarized as "four modernizations": flexibility, agility, intelligence and informationization. Even if the process equipment and process route can meet the needs of producing various products, meet the needs of rapidly changing processes and products, make them flexibly coordinate with the environment, shorten the time to market, and make the production of enterprises flexible and agile, there are still greatly reduced consumption of materials and people in the manufacturing process, highly automated production, intelligent pursuit of human intelligence by machines, and informationization that mainly relies on the power of matter and energy to make information generate value.
Of course, the four development trends of machinery manufacturing industry are not separated, they are organically combined, interdependent and mutually promoting. At the same time, due to the continuous progress of science and technology, there will be new development directions. What we saw before was the development of machinery manufacturing industry on its own line. But as a part of social development, it will also be more widely integrated with other industries. The importance of machinery manufacturing industry in the 2 1 century is manifested in its globalization, networking, virtualization, intelligence and green manufacturing coordinated with environmental protection. It not only liberates human beings from heavy physical labor, but also liberates human beings from tedious mental work such as calculation and analysis, so that they have more energy to engage in high-level creative labor, intelligently improve flexibility, and make the production system have more perfect judgment and adaptability. Of course, all this needs further efforts from all of us.