Plastic cutting is machined

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1 preface is plastic make use the methodological production that shapes directly commonly, but some model shape directly difficult or tall to its precision requirement when, must undertake cutting is machined. Model the device that cutting treatment uses treatment metal commonly. Differ as a result of plastic function and metal bigger, and plastic breed is various, its sort also does not have bigger difference with function, so model the characteristic that cutting treatment has its oneself. The influence that 2 plastic function machine to cutting heats up function and metallic photograph to compare, plastic thermal capacity is small, thermal conductivity is poor (its coefficient of thermal conductivity has a metal only 3 millesimals or smaller) , hot coefficient of expansion is big (bigger than the metal 1.

5 ~ 20 times) . The quantity of heat that reason produces because of attrition in cutting process basically passes cutting tool. Although a few quantity of heat send model, because pass into model hard in-house, produce local overheat extremely easily, cause model become angry, melt, burn even. And temperature is exorbitant, model flexibility is out of shape aggravate, influence model exterior quality and dimension precision, serious when cause workpiece spring, cause an accident even. Accordingly, treatment middling uses refrigerant (use commonly compress air) drop temperature. The stretch model with stretch model plastic quantity measures the 1/10 ~ 1/16 that has a metal only, when cutting is machined, if cutting tool and clamping apparatus use force to it,pass big, can cause bigger flexibility to be out of shape, influence model machine precision, serious when it is difficult to can cause treatment. Because this is when cutting treatment, the parameter of cutting tool wants reasonable, point wants sharp, cutting dosage should proper, in order to reduce cutting force. Clamping force cannot pass big. Plastic the characteristic that cuts bits is when high speed cutting, what be cut is plastic and drossy condition of the frit that show glue, encounter cold namely sclerotic. In machining a process, extremely drossy easy conglutinate is on cutting tool, change the point of view of cutting tool thereby, increase cutting depth, influence model machine precision, because this answers,seasonable eliminate cuts bits. In addition plastic make in cutting treatment process, meeting generation cuts bits dust in great quantities, must take significant dust control step, make the dust content in air accords with state specified standards. The chooses cutting tool material of material of 3 cutting tool basically has high-speed steel, hard alloy, diamond to wait. Cutting is general plastic, material of before can be being chosen two kinds of cutting tool. Be compared and character, the sex grinding profit of high-speed steel is better, choose high-speed steel cutting tool and careful blade is ground, can make cutting tool point sharper, but its durability under hard alloy cutting tool. Machine appropriate of glass reinforced plastics to choose diamond cutting tool. Because of glass reinforced plastics by plastic two kinds of material are combined and become with fibre glass, when cutting soft hard alternate with, interrupted cutting, minutely concussion amounts to above 1 million times, cutting tool is ground even more easily than material of cutting pure horniness blunt, because this should choose the diamond cutting tool with wonderful wearability. The choice of parameter of geometry of 4 cutting tool should reduce cutting force as far as possible when choosing parameter of cutting tool geometry, drop cutting temperature, in order to assure model machine quality, raise productivity and cutting tool durability as far as possible, reduce finished cost. Parameter of geometry of discussion lathe tool is emphasized to choose a principle below. Before the size of the horn before horny lathe tool affects cutting result directly. Horn chooses a little bit big to be able to reduce cutting to be out of shape before, cutting force, reduce the generation of heat in metal cutting, drop cutting temperature, reduce radius of blunt circle of cutting tool point, make the crucial point sharp; Can increase model at the same time treatment quality. But before horn crosses congress to weaken cutting tool intensity, medicinal powder hot condition becomes poor, cutting temperature is elevatory instead, make cutting tool durability and model treatment quality drops. Because this is reasonable,choose cutting tool before role is very important. Integrated consideration model answers when the choice the element of material, cutting tool material and face of treatment property tripartite. The experiment proves, machine model when, along with the accretion of the horn before cutting tool, cutting obstruction can be reduced. This is because of great majority plastic compressive strength is more than tensile strength (general big 2 ~ 3 times) , from mechanical angle analysis, the horn before 28 cutting tool is helpful for Du Lanping more greatly more plastic happening strain crack. Reason machines model when, the horn before cutting tool should choose a little bit big; But when processing the data such as glass reinforced plastics, wallop is bigger, to assure cutting tool intensity, horn should take a little bit small before, take negative worth even. Cutting tool material is different, before horny choice is not same also. The bending strength of high-speed steel and concussion tenacity are bigger, can bear greater cutting power, before horn is desirable greater numerical value, in order to reduce cutting force. Processability differs character, horny choice also differs before. When rough machining, cutting deepness and feed are bigger, cutting muscularity, to reduce cutting force, horn should take a little bit big before; When finish machining, cutting rate is average taller, the heat in metal cutting of generation is more, heat up a condition to improve cutting tool to come loose, drop cutting temperature, before horn is somes small more desirable. The size of horny part is opposite after the impact of cutting effect is bigger also. Face of the knife after horn takes great value to be able to reduce cutting tool after and model the attrition between, can make blunt round radius reduces cutting tool point, point is sharp, cut work easily. But hind horn also makes edge intensity is reduced greatly too, cutting tool comes loose heat energy force drops. The horn after choosing cutting tool basically considers cutting ply. Cutting ply is big (be like rough machining) cutting muscularity, make sure to reduce cutting force cutting tool has enough strength, horn should take big cost before, horn should take small cost after; Cutting ply is thin (be like finish machining) , attrition and cutting tool wear away to basically happen after on knife face, and cutting power is not great, cutting tool strength is enough, horn should take a little bit big after in order to reduce hind the attrition of knife face, reduce heat in metal cutting, make the crucial point sharp. Before the lathe tool with commonly used and plastic cutting, hind horny cost refers to a watch 1. Express the point of view of lathe tool reference with 1 commonly used and plastic cutting the horn before plastic material (° ) after horn (° ) hard pvc 1510 ~ of 10 ~ 15 polyolefin get together 4 fluorine ethylene 1515 ~ of 0 ~ 30 polyformaldehyde 1510 ~ of 0 ~ 25 polypropylene acerbity ester 1010 ~ of 0 ~ 25 polyamide.

The tool cutting edge angle of lathe tool of 3 other parameter, deputy slant the parameter such as circular arc radius also meets horn, point of a knife conduct heat to cutting tool, model the respect such as force of exterior surface roughness, cutting produces an effect. Reduce advocate, deputy slant horn, increase radius of circular arc of point of a knife, ameliorable cutting tool comes loose hot condition, make cutting tool wears away reduce; Model exterior surface roughness is reduced. But advocate, deputy slant horn passes small or radius of circular arc of point of a knife is too big, cause cutting resistance, especially the cutting component of force that workpiece cuts deep way increases, cause model easily be out of shape. Because this is in model below the condition that stiffness allows, ability is taken lesser advocate, deputy slant horn and radius of bigger circular arc of point of a knife. The choice cutting rate of 5 cutting dosage rises cutting speed to be able to shorten cutting time, improve productivity, and cutting force won't increase, model the effect that exterior surface roughness also gets cutting rate scarcely. But cutting rate increases can make cutting temperature apparently elevatory, model meeting generation heat expands and heat is out of shape, become angry even, the influence machines quality, and cutting tool wears away aggravate, durability is reduced (cutting rate rises 10% , cutting tool durability can shorten for original 40% ~ 60%) , such making that change a knife, grind knife, right the knife is adjusted wait for auxiliary time to increase, productivity drops somewhat instead, because this wants control cutting rate. The cutting speed when commonly used and plastic treatment refers to a watch 2. Express the cutting dosage with 2 commonly used and plastic cutting plastic material cutting measurement of deepness of fast feed cutting expects (Mm) is plastic material cutting speed (Mm/min) feed (Mm/r) cutting deepness (Mm) polyformaldehyde 120 ~ 1800.

1 ~ 0.

250.

12 ~ 0.

5 polyamide 150 ~ 1800.

05 ~ 0.

380.

12 ~ 0.

5 get together carbonic acid fat 150 ~ 3000.

12 ~ 0.

50.

12 ~ 0.

5 polyolefin, get together 4 fluorine ethylene 90 ~ 2250.

05 ~ 0.

250.

12 ~ 0.

5 polystyrene 230 ~ 3000.

03 ~ 0.

Lamination of 1- phenolic aldehyde is plastic 150 ~ 6000.

1 ~ 0.

25-0.

25 ~ 0.

Lamination of phenolic aldehyde of 75 fibre glass is plastic 45 ~ 60 ∠ 0.

25- organic glass 15 ~ 800.

1 ~ 0.

25-0.

15 ~ 0.

When 2 feed and cutting deepness feed and cutting deepness increase, also make cutting handling time shortens, and come loose because of was being improved hot condition, cutting temperature and cutting tool durability drop not quite, won't make change a knife, grind the auxiliary time such as the knife to increase apparently, reason can improve productivity. But the addition as feed and cutting deepness, cutting force can increase significantly (feed increases one times, cutting force increases 70% ~ about 80% , cutting deepness increases one times, cutting force almost twice increases) , make easily model generation is out of shape and the influence machines quality, make workpiece discards as useless even. Model the value still meets exterior surface roughness follow the accretion of feed and increase, because appropriate feed and cutting deepness should choose when this treatment. The feed with commonly used and plastic cutting and cutting deepness refer to a watch 2. 6 last words are being machined plastic make when, answer to ask according to plastic function and treatment condition, treatment, choose right cutting tool stuff, the geometrical parameter of logical choice cutting tool reachs cutting dosage, had solved the special problem in plastic treatment, make the cutting dosage of parameter of cutting tool geometry achieves optimal combination, reduce cutting force in order to achieve, drop cutting temperature, assure to machine quality, raise the goal of productivity. CNC Milling