CNC engraving machine in the development of the domestic from the last few years only have a greater development, the relevant processing plants and use units always keep a keen eye on the trend of the manufacturers, which is also as engraving and milling machine main machine factory does not dare to relax the real reason.As a user of course to choose the right equipment, if the improper selection not only can not make money but will fall into the bitter situation of working for the machine.So what kind of machine tool is a good machine tool?We think the definition of a good machine tool is this: the machine tool that can recover its investment in a short period of time is a good machine tool.CNC machine design service life is generally 7 years, mainly CNC service life, the proportion of money and money will directly affect your business, so careful analysis of the function of selection is a necessary condition for effective investment.
There are already many words for engraving and milling machine (CNC engraving and milling machine) in foreign countries. Strictly speaking, engraving is a part of milling.In addition, there are currently prevalent high-speed cutting MACHINE tools (HSC machines).
Let's start by getting the three models different:
1, CNC milling and machining center for the completion of large milling amount of the workpiece processing equipment.
3. High-speed cutting machine is used to complete medium milling amount and reduce the grinding amount after milling to the lowest processing equipment.
In-depth analysis of the structure of the above equipment can help us make the right choice.
1. From the mechanical point of view, the machine is divided into two parts, the moving part and the non-moving part: the working table, skateboard and cross flower table are the moving part of the bed, and the column is the non-moving part.
(1) CNC milling center:
The non-moving parts have very good rigidity. The moving parts have very good rigidity.
Advantages: can carry out heavy cutting;Disadvantages: Because the moving part is also large, sacrificing the flexibility of the machine tool, it is powerless for small parts and fast feed.
(2) CNC carving and milling machine
The rigidity of the non-moving part requires that the rigidity of the moving part should be flexible, as light as possible, while maintaining a certain rigidity.
Advantage: can carry on the quite fine processing, the processing precision is high.For soft metal can be processed at high speed;Disadvantages: Heavy cutting is not possible due to poor rigidity.
(3) High-speed cutting machine tools
The non-moving parts are very strong. The moving parts are strong and as light as possible.
Advantages: can carry out medium and small amount of cutting (example: general 10 flat cutter, for 45 steel (300) depth of 0.7 is good);Disadvantages: high efficiency and low cost when used correctly, so that the amount of polishing is very little.If not used correctly, it will soon lead to a mountain of tool waste.
How to achieve the above mechanical light, rigid and good contradictory requirements, the key in the mechanical structure of the effort.
(1) The bed body adopts the network structure with high and low bars, and some directly adopt the hexagonal network structure connected with the honeycomb
(2) Super wide columns and beams, as we all know, gantry type structure due to its excellent symmetry and excellent rigidity has been the preferred structure of high speed cutting equipment manufacturers.
(3) For the moving part and CNC milling has a significant difference is to widen the distance between a lot of guide and guide to overcome the problem of bad torque.
(4) In terms of material, meehan cast iron is generally used, that is, inoculation cast iron. When pouring molten iron, a certain proportion of silicon (S) is added to change the internal structure of iron, making it more resistant to stamping and more rigid
(5) The rigidity of the machine tool is mainly used to overcome the moving part in the high-speed movement of the strong impact on the non-moving part, so the guide rail, screw rod requirements some thicker, and strengthen the connection part of the rigid
2. Analysis from the perspective of NUMERICAL control
(1) CNC milling center for CNC system required general speed, spindle speed 0 ~ 8000RPM
(3) High speed cutting machine tools require high speed CNC system and excellent servo motor characteristics, spindle speed around 1500 ~ 30000RPM
3. Programming software analysis
From the point of view of software, CNC milling machining center, high speed cutting machine engraving and milling machine can use standard CAD/CAM software such as: MasterCam Cimatron PE UG.
Milling machine is usually thought that Cimatron dao is better, fully fastidious to the new version of the software tool every moment of the uniformity of cutting quantity, especially the knife into the out of the work of a moment of speed and rounding, and the poor in the inflection point follow algorithm problem (following Error), further put into results and design graphics, CAD part just intuitive three-dimensional entity model has been widely used by IGS into CAM software such as Solidworks for processing.But don't worry, CAD/CAM is growing faster than CNC.
Engraving processing because of the specificity of the tool has quite small Angle control, use TYPE3 as well.
4. Automatic tool changing and automatic tool setting requirements of knife library
Processing center is a decent term, but I think the requirements of knife store must be combined with the reality.
Machining center is to complete a variety of processes in the state of the automatic numerical control equipment, mainly for some fixed mass production, if we are processing a very porous, dental cabinets, and do almost every day (more than one batch of minimum 200) that must be chosen processing center, the mould industry and small batch production unit must not easily on machining center, because the processing center, seen too many manufacturers buy used for CNC milling, use knife library for on the cost of the CNC system is very simple, but the main shaft and knife library, air compressor, and all kinds of the handle will increase the cost,So the price difference for a device is more than 100,000 yuan, and programmers should be clear-headed.Otherwise the tragedy would have happened and the problems would have increased.How about the efficiency? For the production of less than one or two hundred workpieces of the same variety, try not to use the processing center, the efficiency is too low.
What is a good way to improve the efficiency, do not use the knife library, and will not cause manual tool change error, only automatic tool system, a upward, a button, automatic tool tool, direct processing, error in within 0.001 ~.0003m, it is no more efficient than automatic time change.If it is a machining center and no automatic tool setting machine tool and no tool library, but compared with the practice of automatic tool setting machine tool efficiency is much higher than the former., please pay attention to the price of the best brand of knife apparatus automatically such as (Marposs) ten thousand yuan or so, however, and is unlikely to be damaged, so analysis for the Labour of the domestic mould processing, industrial parts and small batch processing if fully consider capital utilization value should not be adopted machining center equipment, in addition, domestic manufacturer of knife library is basically a lot of problems.The imported ones are also quite expensive (BT40's 10 knives are no less than 100,000 RMB).
5. View of high speed cutting equipment
Smart processors must spend a lot of time thinking about machine tool preparation time and the human cost of personnel, we always remember not to remind them in this regard.What we should do is how to give them higher processing efficiency from the processing time of machine tools, and possibly reduce their polishing time.Even zero grinding.High speed cutting equipment of it is to let a slam processors on events do not consider its expensive (around 1.5 million), the cost of a single tell from the use of I think there must be an old saying goes: for some people it is a piece of sweet sweet flesh, for others is a highly toxic poison, Japanese and europeans spare no effort to promote the benefits of high speed cutting and let people use their equipment.Of course, there are some practical ways.8 years of practical experience in the CNC machine tool industry tells me that their cost should be about 600,000 ~ 700,000.Such a high profit margin is to let me see their essence.The gross profit of domestic CNC machine tools should be between (30 ~ 40%).It is reasonable and just profit.If you are willing to maintain their high profits I think it is impossible to make more money at the same time.Take into account the after-sales service and so on.I can't believe their service can solve all the problems in 1-2 days.Because we don't have the technology to do solid fax yet.
From the perspective of revitalizing national industry, the development of domestic machine tool factories should be supported.The essence of high speed cutting is to finish the tool's walking length in a short time.As we all know, distance = speed × time, high-speed cutting due to the current machine tool itself spindle and the use of the tool decided that it can not be good, the current foreign common practice is the first equipment does not use high-speed cutting, and the second or third can consider this equipment.
Successful practices such as: table copy milling to complete most of the cutting (heavy cutting) and the remaining machining allowance of 2 ~ 3mm, the remaining cutting in high-speed machine tools quickly completed, this has a lot of benefits:
1) There are many heavy cutting machines and the processing fee is very low.
2) Large amount of processing, low precision requirements easy to achieve.
3) Knives are cheap.
4) After turning into high-speed cutting, the cutting amount of the first tool is very even because the processing object is nearly formed.
5) Rapid and accurate forming.
6) Avoid too much polishing, with accurate size.
7) Although the tool is expensive, but the time is short, the cutting quantity is not big, the performance price ratio is very good.
8) Many subtle points, such as small Angle conductivity, etc., can be processed carefully without the help of electric spark.
9) Excellent surface finish (mirror effect).
In this way, the equipment is the way to win, because it has a surplus of 2 ~ 3 mm, so do two calibration G54 baffle on the work table XY to complete the workpiece clamping problem, and for the workpiece cutting is not much is directly completed in the high-speed machine tool.
6. There is another problem to discuss which is the principal axis
For CNC milling and machining center because of the requirement of low speed large torsion data, so must need the spindle gearbox to improve the torque ratio of low speed and poor accuracy is inevitable, so it is unlikely to use a small radius tool.For
carving and milling machine to spindle work in 20 ~ 30 thousand RPM can work, rotation accuracy is generally 2 or so, but the phenomenon is very serious, so must use spindle, motor and spindle is one.For high-speed cutting equipment, it is required to have a built-in motorized spindle, and at a low speed must also have a certain torque to keep the spindle working temperature constant spindle power in 7.5 ~ 8KW above the speed of spindle more than 25000RPM.
Knowing the differences between the three, it will be easy for us to choose.
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