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編號
無錫太湖學院
畢業(yè)設計（論文）
相關資料
題目： 數(shù)控火焰切割機的設計
信機 系 機械工程及自動化專業(yè)
學 號： 0923083
學生姓名： 王文佳
指導教師： 龔常洪（職稱：副教授 ）
（職稱： ）
2013年5月25日
目 錄
一、畢業(yè)設計（論文）開題報告
二、畢業(yè)設計（論文）外文資料翻譯及原文
三、學生“畢業(yè)論文（論文）計劃、進度、檢查及落實表”
四、實習鑒定表
無錫太湖學院
畢業(yè)設計（論文）
開題報告
題目： 數(shù)控火焰切割機的設計
信機 系 機械工程及自動化 專業(yè)
學 號： 0923083
學生姓名： 王文佳
指導教師： 龔常洪（職稱：副教授 ）
（職稱： ）
2012年11月28日
課題來源
生活實踐
科學依據(jù)（包括課題的科學意義；國內外研究概況、水平和發(fā)展趨勢；應用前景等）
（1）課題科學意義
在機械加工過程中，經(jīng)常需要對板材進行切割操作，板材切割常用方式有手工切割、半自動切割機切割及數(shù)控切割機切割。手工切割靈活方便，但手工切割質量差、材料浪費大、尺寸誤差大、后續(xù)加工工作量大，同時往往工作條件惡劣，生產(chǎn)效率低。半自動切割機中仿形切割機，切割工件的質量較好，由于其使用切割模具，不適合于單件、小批量和大工件切割。其它類型半自動切割機雖然降低了工人勞動強度，但其功能簡單，只適合一些較規(guī)則形狀的零件切割。數(shù)控切割機切割相對手動和半自動切割方式來說，可有效地提高板材切割的切割質量、效率，減輕操作者的勞動強度。目前在我國的一些中小企業(yè)甚至在一些大型企業(yè)中使用手工切割和半自動切割方式還較為普遍。隨著現(xiàn)代機械工業(yè)的發(fā)展，對板材切割加工的工作效率和產(chǎn)品質量的要求也同時提高，因而數(shù)控切割機的發(fā)展和提高迫在眉睫。數(shù)控火焰切割機作為最常見的切割金屬板材的設備，對于它的設計課題符合現(xiàn)代工業(yè)發(fā)展的要求。
（2）數(shù)控火焰切割機的研究狀況及其發(fā)展前景
目前，我國機械加工行業(yè)中鋼板下料普遍采用手工—乙炔切割，這種現(xiàn)象不僅存在于小規(guī)模單件生產(chǎn)的小型企業(yè)，也存在于大批量生產(chǎn)的大型企業(yè)中，而國外企業(yè)的下料工序大部分采用了數(shù)控氧—乙炔或數(shù)控等離子切割方法，不僅可提高材料利用率，而且改善了產(chǎn)品質量，優(yōu)化了工作環(huán)境，使人員工作效率得到了提高。之所以數(shù)控下料不能在我國普及主要有三個方面原因：資金問題、設備故障維護問題、操作問題。因此研制功能不是很強大但操作簡單，性能可靠，價格相對便宜的實用型的火焰切割機就迫在眉睫．這也就意味著目前設計和制造經(jīng)濟型數(shù)控火焰切割機在國能將有廣闊的市場。
研究內容
① 熟悉數(shù)控火焰切割機的發(fā)展歷程，特別是近十幾年來的龍門式火焰切割機
② 熟練掌握火焰切割機機械部分的設計；
③ 熟練掌握電氣控制系統(tǒng)的設計
④ 掌握單片機的原理及選取方法
⑤ 能夠熟練使用UG，CAD。針對三維UG圖，將UG圖轉換為二維CAD。
⑥ 熟練使用CAD提供的圖層工具。
擬采取的研究方法、技術路線、實驗方案及可行性分析
（1）實驗方案
通過不同的零件的選取與比較，選擇最佳方案，以避免設計過程中可能出現(xiàn)的計算結果與設計要求不符的嚴重情況，再參考國內外類似產(chǎn)品的數(shù)據(jù)，以避免設計結果難以符合市場需求的后宮。
（2）研究方法
①用UG對產(chǎn)品進行三維設計，仔細觀察產(chǎn)品的外觀，思考產(chǎn)品的可能缺陷
②在不同的原始數(shù)據(jù)下，對同一個方案做不同的計算，在不同的零件組成下，比較各個方案的優(yōu)劣。
研究計劃及預期成果
研究計劃：
2012年11月7日-2012年11月27日：按照任務書要求查閱論文相關參考資料，填寫畢業(yè)設計開題報告書。
2012年11月28日-2013年2月12日：填寫畢業(yè)實習報告。
2013年2月17日-2013年3月2日：按照要求修改畢業(yè)設計開題報告。
2013年3月5日-2013年3月16日：完成畢業(yè)設計的緒論。
2013年3月19日-2013年5月11日：設計方案計算。
2013年5月14日-2013年5月18日：完成零件與裝配圖。
2013年5月19日-2013年5月20日：畢業(yè)論文撰寫和修改工作。
預期成果：完成數(shù)控火焰切割與三維圖的的機械部分與電氣控制系統(tǒng)的設計，以及二維圖與三維圖的成型。
特色或創(chuàng)新之處
①使用UG畫圖，將三維圖轉為二維圖。
② 采用固定某些參量、改變某些參量來研究問題的方法，思路清晰，簡潔明了，行之有效。
已具備的條件和尚需解決的問題
① 實驗方案思路已經(jīng)非常明確，已經(jīng)具備使用UG制圖能力和圖像處理方面的知識。
② 使用UG制圖的能力尚需加強。
指導教師意見
指導教師簽名：
年 月 日
教研室（學科組、研究所）意見
教研室主任簽名：
年 月 日
系意見
主管領導簽名：
年 月 日
英文原文
CNC flame cutting basic common sense
The basic knowledge of CNC flame gas cutting
(A) the basic working principle of gas cutting and gas cutting process
Heat using a gas flame cutting the workpiece is preheated to at a certain temperature, the discharge speed cutting oxygen stream, so that combustion and gives off heat to achieve cutting method is called torch cutting.
The oxygen cutting process has the following three stages:
1, the beginning of the preheating gas cutting, using a gas flame (oxygen-acetylene flame, oxygen, propane flame) of the workpiece to be cut at the ignition of the metal material is preheated to approximately 1100 to 1150 ° C) (For low carbon steel.
Combustion emit high-speed cutting oxygen flow reached lighted metal intense burning in an oxygen stream.
3, blowing slag metal oxide combustion generated by the oxygen stream to blow off the incision is formed, so that the metal separation, the completion of the cutting process.
(B) gas welding, gas cutting equipment used in the composition of the
Gas welding, gas cutting equipment, oxygen bottles, oxygen regulator, acetylene bottles (acetylene generator), acetylene regulator, the tempering insurance, torch (torch) and rubber tube.
(C) what is good notched
Cutting the middle of the notched surface after the whitening did not burn scar notched without waste side of the phenomenon
(D) gas cutting metal shall comply with the following conditions:
1) the melting point of the metal oxide should be less than the melting point of the metal. Table 1 - 1 are some common melting point of the metal and its oxide.
2) metal with oxygen combustion can release a lot of heat, and the thermal conductivity of the metal itself.
The gas cutting conditions metal iron, low carbon steel, medium carbon steel and low alloy steel and titanium. Other commonly used metals such as cast iron, stainless steel, aluminum and copper, etc., must use special method or melting method of oxyfuel cutting.
8mm sheet, it is not easy to CNC gas cutting.
CNC flame cutting
Gas cutting accuracy is the error between After cutting geometry with its drawing size comparison, cutting the quality of the workpiece is cut off
The surface roughness of the surface, the melting degree of collapse section on the edge of the incision, the incision edge is dross and the uniformity of kerf width.
First, the impact of steel flame cutting quality three basic elements (gas, cutting speed, cutting nozzle height)
1. Gases (oxygen, combustible gas and the flame adjusted)
(1) Oxygen Oxygen is necessary for combustion of the combustible gas, in order to provide the energy required for steel reaches the ignition temperature; addition, oxygen is carried out after the steel is preheated achieve ignition combustion as necessary. Cutting steel with oxygen must have a high purity of more than 99.5%, the general requirements, some advanced countries by industry standards, the oxygen purity of 99.7%. The oxygen purity decreasing by 0.5%, steel plate cutting speed should be reduced by about 10%. If the oxygen purity is reduced by 0.8% to 1%, not only cutting speed decreased by 15% -20%, while the slotted also will be wider, hanging at the bottom of the incision the Residue and clean difficult, significant deterioration of the quality of the cutting section, gas consumption also increases. Obviously, this reduces the production efficiency and cutting quality, the production costs are also significantly increased (see Figure 9-1).
Figure 9-1 under the same oxygen pressure, oxygen purity of cutting time and oxygen consumption.
The use of liquid oxygen cutting, although the one-time investment, but in the long run, its comprehensive economic indicators are much better than imagined.
The stability of the gas pressure on the cutting quality of the workpiece is also essential. The oxygen pressure fluctuations will cut the apparent deterioration of the quality of cross-section. The air pressure is adjusted according to the type of the cutting nozzle, the cutting of the plate thickness. Cutting if the oxygen pressure exceeds a predetermined value, does not improve the cutting speed, but the cutting section decline in the quality of the dross is difficult to be cleared, increasing the processing time and cost of cutting.
Table 9-1 is commonly used in gas welding machine factory production the GK1 series of fast cutting nozzle (ie the Laval nozzle structure cutting nozzle) using the parameter (manufacturers may at any time modify the parameters should be cutting nozzle subject to the attached document, this table is for reference).
(2) flammable gas flame cutting, commonly used flammable gases such as acetylene, gas, natural gas, propane, some foreign manufacturers also use MAPP, namely: methane + ethane + propane.
Generally, the combustion speed, high combustion value of the gas is suitable for sheet metal cutting; low combustion value, the slow combustion of flammable gas is more suitable for cutting slab, especially steel sheet of a thickness of more than 200mm, such as a gas or gas be cut, you will get the desired cut quality, but the cutting speed will be slightly lower.
In comparison, the acetylene is much more expensive than natural gas, owing to resource constraints in the actual production, the general use of acetylene gas, but at the same time cutting the slab require high cutting quality and adequacy of resources, it will consider the use of natural gas.
(3) The flame can be adjusted by adjusting the proportion of the oxygen and acetylene the three cutting flame: neutral flame (ie, normal flame), oxidizing flame, reducing flame, as shown in Figure 9-2.
The normal flame characterized in that no free oxygen in the reduction zone and the activated carbon, there are three distinct regions, the flame core distinctive outline (approximately cylindrical). The flame core component of acetylene and oxygen, and its ends were uniformly round and shiny shell. The housing is made of red hot carbon particles. Flame core temperature up to 1000 ° C. Reducing zone in the flame core, a significant difference with the flame core is its brightness is darker. Reduction zone by the product of incomplete combustion of acetylene - carbon monoxide and hydrogen, the reduction zone temperature up to 3000 ° C or so. Completely Waiyan i.e. the combustion zone is located outside of the reducing zone, it is composed of carbon dioxide and water vapor, nitrogen, its temperature varies between 1200 to 2500 ° C.
Oxidizing flame is generated in the case of excess oxygen, the flame core conical, length shortened significantly, the outline is not clear, the brightness is dim; Similarly, the reduction zone and outer flame has been shortened, the flame was purple blue combustion accompanied by sound, the sound of the size of the pressure of oxygen, oxidizing flame temperature is higher than normal flame. If you are using the oxidizing flame cutting will make the cut quality significantly deteriorated.
Reducing flame is generated in the case of excess acetylene flame core is no obvious silhouette green edge, the flame end of the core, to determine the excess of acetylene in accordance with the green edge; reducing zone is unusually bright, almost The flame core lumped together; Waiyan the yellow. When the excess acetylene is too far, black smoke, which is caused because of the lack of necessary oxygen acetylene flame in combustion.
Preheat the energy of the flame size and cutting speed, cut quality are all very close. With the cut workpiece thickness increases and the cutting speed to accelerate, the energy of the flame also should increase as, but not too strong, particularly when the slab is cut, the the metal combustion heat of reaction generated increases, strengthening the cutting point preheat capabilities, cutting-edge, then, too strong preheating flame will make serious melting collapsed on the edge of the cut edge. Too weak to preheat flame, the steel will not get enough energy to force to reduce the cutting speed, even cutting process is interrupted. So preheating flame strength and cutting speed relationship of mutual restraint. In general, the steel cutting 200mm neutral flame can get a better cut quality. Used in the cutting of steel plates should restore preheat flame cutting, because the reducing flame of the flame length, flame length should be at least a thickness of 1.2 times or more.
(2) cutting speed
The cutting speed of the steel sheet is corresponding with the burning rate of the steel in an oxygen. In the actual production should be based on the performance parameters of the cutting nozzle, gas type and purity, steel plate thickness to adjust the cutting speed. Cutting speed directly affects the stability of the cutting process and the quality of cutting section. If you want to artificially increase the cutting speed to improve production efficiency and slow down the cutting speed to best improve the quality of the cutting section, it is impossible, only make the poor quality of the cutting section. Too fast cutting speed can cause the cutting sections with quality defects such as dents and dross, serious may result in cutting interrupt; too slow cutting speed make the incision on the edge of the melting edge of collapse, the lower edge rounded, cutting cross-section in the second half part of the flush-shaped deep groove pit.
By observing the characteristics of the slag discharged from the incision, adjust to the appropriate cutting speed.
In the normal flame cutting process, cutting oxygen stream relative to the vertical cutting torch slightly at an angle, and its corresponding offset is called drag amount (see Figure 9-3). Speed ??is too low, there is no amount of post-drag, offset the workpiece cut below the mouth of the fire bouquets to the cutting direction. Improve the running speed of the torch, the fire bouquet will be offset in the opposite direction, when the fire bouquet and cutting oxygen flow parallel to the cutting speed. Speed ??is too high, the fire bouquet significantly after partial, as shown in Figure 9-4.
Cutting nozzle and cut the height of the workpiece surface
Steel plate flame cutting process, the cutting nozzle to cut the height of the work surface is one of the main factors in decision notch quality and cutting speed. Different thickness of the plate, using different parameters of the cutting nozzle, adjust the height. In order to obtain high quality cuts, the cutting nozzle to the height of the workpiece surface to be cut in the cutting process must be kept basically the same.
Second, the thermal deformation of the control
Will allow to be cut due to the unevenness of the steel sheet heating and cooling, the material of internal stress the role of the workpiece in the cutting process, different degrees of bending or displacement of - i.e. heat deformation, the specific performance is the deviation of the shape of the twisting and cutting size . Material internal stress can not be balanced and completely eliminated, it can only take some measures to try to reduce the thermal deformation.
Third, the steel surface preparation
The steel from the steel plant through a series of intermediate links to the cutting workshop, during that time, the steel surface will inevitably produce a layer of oxide. Furthermore, the steel sheet is also produced during the rolling process the layer of oxide is attached to the surface of the steel sheet. These oxide has a high melting point, is not easy to burn and melt, warm-up time, reducing the cutting speed; heated at the same time, scale splash, can easily cause congestion, reduce the service life of the cutting nozzle cutting nozzle. Therefore, prior to cutting, it is necessary on the surface of the steel sheet rust pretreatment.
The common method is to shot blasting, rust after painting. Upcoming small iron sand blasting machine sprayed into the surface of the steel plate, rely on the impact of iron ore to steel descaling, then sprayed flame retardant, electrical conductivity and good anti-rust paint.
Rust paint pretreatment before steel cutting has become an indispensable part in the production of metal structures.
Fourth, CNC flame cutting quality defects cause analysis
In the actual production process, often one way or another quality problems, generally there are several defects: edge defects, cutting cross-section defects, dross, cracks, etc.. And quality accidents caused by many reasons, if the oxygen purity to ensure normal, normal operation of equipment, causing flame cutting quality defects is mainly manifested in the following aspects: cutting torch, cutting nozzle, the quality of the steel itself, steel plate.
1. On the cutting edge of quality defects
This is caused due to melting of quality defects.
(1) on the edge of collapse edge
Phenomenon: the edge of the melting too quickly, resulting in a rounded edge collapse.
Reasons: (1) cutting speed is too slow, too preheat flame;
(2) cutting height between the nozzle and the workpiece is too high or too low; cutting nozzle number is too large, excess oxygen in the flame.
(2) teardrop-shaped melting string beans (see Figure 9-9)
Phenomenon: the upper edge of the cut to form a series of teardrop-shaped melt beans.
Reasons: (1) the surface of the steel corrosion or oxide;
(2) cutting height between the mouth and the steel is too small, preheat flame is too strong;
(3) cutting height between the mouth and the steel is too large.
(3) the upper edge of the mat section and presents the the eaves shape (see Figure 9-10)
Phenomena: in the upper edge of the cut forming the eaves-like projecting edge collapse.
Reasons: (1) Preheat the flame is too strong; the ② cut too low an altitude between the mouth and steel;
(3) Cutting speed is too slow; cutting height between the nozzle and the workpiece is too large, the cutting nozzle number is too large, the the preheat flame in oxygen excess.
(4) the upper edge of the cutting section of dross (see Figure 9-11)
Phenomenon: on the edge of the incision depression and dross.
Reasons: (1) cutting height between the nozzle and the workpiece is too large, cutting oxygen pressure is too high; (2) Preheat the flame is too strong.
2. The cutting section rugged flatness
(1) cutting the section below the upper edge, a concave defect (see Figure 9-12)
Phenomenon: the receiving depression, on the edge of the cutting section at the upper edge there are different degrees of melting mat section.
Reasons: (1) cutting oxygen pressure is too high;
(2) cutting height between the nozzle and the workpiece is too large; the cutting nozzle becomes clogged, the wind line disturbed deformation.
(2) slotted be contracted from top to bottom (see Figure 9-13)
Phenomenon: slotted wider at the top.
Reasons: (1) cutting oxygen pressure is too high;
(2) cutting height between the nozzle and the workpiece is too large; the cutting nozzle becomes clogged, the wind line disturbed deformation.
Phenomenon: slotted the narrow width, bell-shaped.
Reasons: (1) the cutting speed is too fast, cutting oxygen pressure is too high;
② cutting nozzle number is too large, too much cutting oxygen flow;
(3) cutting height between the nozzle and the workpiece is too large;
(4) cutting section recess (see Figure 9-15)
Phenomenon: the cutting section, especially the middle part with depression.
Reasons: (1) cutting speed is too fast; (2) to use the cutting nozzle is too small, the cutting pressure is too low, cutting nozzle is clogged or damaged;
(3) cutting oxygen pressure is too high, the wind line blocked deterioration.
(5) cutting section showing a corrugated shape (see Figure 9-16)
Phenomenon: Cutting Section uneven, showing a large corrugated shape.
Reasons: (1) cutting speed is too fast; (2) cutting oxygen pressure is too low, cutting nozzle clogging or damage, deterioration of air line;
(3) using the cutting nozzle number is too large.
(6) the angular deviation of the vertical direction of the incision (see Figure 9-17)
Phenomenon: a vertical incision, a bevel.
Reasons: ① torch and the workpiece surface is not perpendicular to; ② the wind line is not correct.
(7) under the edge of the incision into rounded corners (see Figure 9-18)
Phenomenon: the lower edge of the incision have different degrees of melting, rounded shape.
Reasons: ① cutting nozzle clogging or damage, deterioration of air line; ② cutting speed is too fast, cutting oxygen pressure is too high.
(8) the recess and the lower edge of the lower part of the incision into the rounded corners (see Figure 9-19)
Phenomenon: close to the lower edge of the depression and the lower edge is melted into a fillet.
Cause: The cutting speed is too fast, the cutting nozzle clogging or damage to, deterioration of air line blocked.
3. Roughness defects of the cutting section cutting cross-section of the roughness of the directly affect subsequent step, the processing quality of the cut surface roughness and ahead of the amount of its depth of c