High speed milling machines the computation of efficiency and analysis

The computational  that machines efficiency according to traditional cutting theory, cutting machines efficiency Zw(cm3/min) to be able to calculate through following formula:  of Ap of × of F of × of V of  Zw ＝ (1) in type: V-- cutting speed, f -- feed, ap -- basis of cutting deepness  analysis and research, we think type (1) the computation that does not apply to high speed milling to machine efficiency, the reason basically has at 2 o'clock: The main shaft rotate speed of milling machine of ① high speed is quite high (if milling machine of HSM-700 high speed is highest turn up 42000r/min, the rotate speed when treatment is planar also is in 35000r/min above) , so high rotate speed makes cutting tool is not each turn to be in cutting metal; ② is in effective treatment, the rotate speed of set and feed are the biggest rotate speed and the biggest feed only, actual cutting tool rotate speed and feed hour are changing (the in measuring a function to be able to show whole cutting process oneself change circumstance of HSM-700 machine tool) , the actual rotate speed in cutting process and feed always achieve higher cost quickly to fall very quickly again from inferior value inferior value, change repeatedly so, this is the objective report of milling process, and rotate speed and feed can maintain in unlike turning process constant and changeless.  because this, we put forward to use the metallic purify inside unit time to measure Z(cm3/min) to express to machine efficiency, namely:  of Z ＝ W/t (2) in type: W-- total metallic purify measures cutting process (Cm3) , t -- cutting time (type of Min)(＞ 0) (2) more the actual condition that accords with high speed milling, with type (2) the computation that comes true very easily to machine efficiency to high speed milling, also facilitate different milling machine adds what work efficiency leads to compare at the same time.  for example, machine some spare parts on average milling machine so, produce cycle to shorten, one part part uses treatment of high speed milling machine now. Such, the treatment efficiency that can compare facilities of two kinds of treatment through the treatment of this spare parts. Because the exterior quality demand of this spare parts is not high, high speed milling and common milling all can achieve a requirement. In fact, the surface roughness of spare parts surface that treatment of high speed milling gives should be machined than common milling low 1 ～ 2 grade. Measure Z ＝ W/t with the metallic purify inside unit time (Cm3/min) express to machine efficiency. A few time in milling is being taken to machine a process in the experiment paragraph, record handling time, measure in each time paragraph the bulk of around of spare parts treatment is poor, through type (2) computation gets Z is worth. Take the average of Z through measuring computation for many times, this average can regard more accurate Z as the value. To the process of high speed milling of afore-mentioned spare partses, by type (2) the Z value that calculates is: Z (high speed) ＝ W/t ＝ 25.

296cm3/min presses type namely according to traditional cutting theory (1) calculate: 100 × of × of Dn/1000 of Zw ＝ π Vf/n × 0.

× of 1 × Ap 0.

1 ＝ 376.

8cm3/min compares Z (high speed) with Zw, the efficiency of treatment of high speed milling with apparent Zw and this actual part differs very big.  2. Of efficiency of treatment of different milling machine outside comparing the milling machine that some institute uses  at production at present to eliminate milling machine of HSM-700 high speed, still have the milling center of homebred vertical milling machine and entrance. Homebred milling machine is milling machine of lifting platform of the XK5040-1 that factory of the first machine tool produces the Beijing that 20 centuries purchase at the beginning of 90 time vertical (the following abbreviation is homebred and common milling machine) , basically use at spare parts rough machining to reach at present a few cast-iron with steel treatment; Importing milling center is center of beautiful homebred VF-0 HAAS milling (the following abbreviation imports average milling machine) , can use at rough machining and finish machining.  to afore-mentioned spare partses, the cutting efficiency that machines on homebred and average milling machine is: Z(country general) ＝ W/t ＝ 3.

073cm3/min is in the cutting efficiency that imports the treatment on average milling machine: Z(Enter general) ＝ W/t ＝ 7.

277cm3/min Z(high speed) respectively with Z(state general) enter general with Z() undertake comparative, have: Z(High speed) / Z(state general) ＝ 8.

High speed of 232  Z() / Z(enters general) ＝ 3.

476  are mixed by afore-mentioned computation can see quite, the metallic purify rate that machines this spare parts on high speed milling machine is quite high, more as more apparent than its advantage as photograph of homebred and average milling machine (mirror according to jockey person, had appeared even efficiency of treatment of high speed milling machine is 10 times faster than homebred and average milling machine the circumstance of above) . Of course, qualitative to different capable person, different figure and the spare parts that different treatment asks, the treatment efficiency of different milling machine is not identical. To machining the part with the large part with larger area or particularly complex form, high speed milling machine has more distinct treatment efficiency advantage. The advantage basically reflects the efficiency of high speed milling machine to be mixed for N of tall cutting tool rotate speed tall feed speed Vf. In be machined actually, the impact that feed speed Vf leads to machining effect often bigger.  3.

The treatment efficiency that considers cost factor compares  to machine efficiency to must contain certain tie requirement quite, should join the real case of the enterprise, the consideration machines efficiency and the impact that produce cost. With type (the treatment efficiency E that Z divides the treatment efficiency that 2) gets to expressed to consider cost factor with finished cost C (Cm3/min · 10 thousand yuan) , namely: E＝ Z/C (3) type (3) in, for computation handy, set finished cost C to basically be production charge (include facility cost, equipment to safeguard charge of charge, cutting tool loss to wait) , assume high speed milling machine, homebred and average milling machine, entrance upholds charge of average milling machine daily equal. To can reflect effective treatment efficiency objectively, to arriving in January 2001 in May 2002 this one longer use circumstance has paragraph of machine tool inside quite: Milling machine of  Switzerland MIKRON HSM-700 high speed every value RMB C0 (high speed) ＝ 2 million yuan; Because price of machine tool component is high, the fee that is used at machine tool blame to be safeguarded daily (include corrective maintenance, change component) for C2 (high speed) ＝ 9.

50 thousand yuan; The cutting tool that uses on high speed milling machine all is entrance milling cutter, the price is relatively high, plus lack the cutting that is aimed at different cutting tool and hardware data to use quantity standard, make the use cost of high speed milling cutter higher, accordingly, from last year first up to now, charge of loss of high speed milling cutter is C3 (high speed) ＝ 14548.

13 yuan.  United States produces center of VF-0 HAAS milling is the common milling center that imported 1998, value RMB C0(enters general at that time) ＝ 800 thousand yuan; Machine tool performance characteristics is better, divide outside be being safeguarded daily, do not have the breakdown that occurrence need maintains up to now, c2 (enter general) ＝ 0.

450 thousand yuan; Like high speed milling machine, uses cutting tool all is entrance milling cutter, outside wearing away except normal cutting tool, very few occurrence cutting tool is not normal loss, charge of milling cutter loss enters general for C3() ＝ 2195.

26 yuan.  milling machine of lifting platform of the XK5040-1 that from Beijing factory of the first machine tool purchased 1992 vertical, be worth general of RMB C0(state when current price) ＝ 600 thousand yuan; Basically use at spare parts rough machining at present, although precision is not tall, but performance is steadier, divide outside be being safeguarded daily, did not appear big trouble. To its the operating system undertook transforming 2000 (transhipment of through cargo Xi Menzi operating system) , the charge that transform and overhauls is C2 (country general) ＝ 6.

450 thousand yuan; Use entrance cutting tool to also use homebred cutting tool already on this machine tool, charge of milling cutter loss is C3(state general) ＝ 1377.

62 yuan.  sets the use fixed number of year of the machine tool to be 20 years, according to sharp depreciation law, the machine tool is annual depreciation 5% , arrive 2002, the current cost of 3 kinds of milling machine is respectively:  C1(high speed) ＝ (1/4)C0(high speed) [(1 - 5% × 3) + 3 (1 - 5% ) ] ＝ 185 (10 thousand yuan) C1 (enter general) ＝ C0 (into general) (1 - 5% × 4) ＝ 64 (10 thousand.

E(of 10 thousand yuan of  enters 1291cm3/min · general) ＝ Z (into general) / (C1(enters general) ＋ C2(enters general) ＋ C3(enters general) ) ＝ 0.

1125cm3/min · general of state of E(of 10 thousand yuan of  ) ＝ Z (country general) / (C1(state general) general of ＋ C2(state) general of ＋ C3(state) ＝ 0.

0840cm3/min · can be seen 10 thousand yuan as a result by computation, after considering cost factor, high speed milling has distinct efficiency advantage no longer (with the treatment that imports common milling center efficiency is close to) . This explains as a result quite, the use cost of high speed milling is at present higher (its facility cost, safeguard charge and charge of cutting tool loss to compare tower above of general accuracy machine tool a lot of) . Although  uses high speed milling to return the cutting efficiency of short of economy at present, but do not explain high speed milling does not have an advantage. Above all, above paragraphs considered analysis of milling efficiency socioeconomic to produce cost only, did not consider time benefit. Develop at full speed in the technology today, time often is mainer economic factor. Treatment of high speed milling is in shorten the advantage that machines man-hour respect is apparent. Next, above paragraphs place makes treatment efficiency is quite all can machine in high speed milling machine and average milling machine same undertake below the premise of kind of spare parts, in fact a lot of do not suit (or cannot) the spare parts that machines on average milling machine (be like Bao Bi spare parts or taller to machining exterior quality to ask spare parts) can machine with high speed milling machine only. The 3rd, technology of high speed milling regards a kind of new processing technique as the process that in our country honest all previous develops ceaselessly, machine efficiency to achieve the economy of high speed milling, must study mechanism of high speed milling deep, accelerate the scientific research that has technology of high speed milling to develop, strengthen manufacturing management at the same time, improve handlers quality. Believe as the ceaseless development that studies to technology of high speed milling, the problem such as the economy of treatment will get very good solve.  4.

Conclusion  (1) manufacturing practice makes clear, spare parts of treatment of high speed milling machine covers a range wide, special apply to treatment area the accurate component with bigger, complex form. Precision of spare parts treatment is tall, percent defective is low.  (2) formula of traditional cutting treatment efficiency does not apply to high speed milling, the treatment efficiency that with the metallic purify inside unit time the capacity states high speed milling is more accurate.  (3) sheet looks from the cutting efficiency of the machine tool, high speed milling machine wants tower above average milling machine is very severalfold, but the use cost of high speed milling machine is at present higher. When choosing craft plan, can consider to undertake rough machining with average milling machine, have semifinishing machining and precision work with high speed milling machine.  (4) the scientific research development that develops technology of high speed milling deep only, the treatment efficiency dominant position that just can develop high speed milling machine adequately. CNC Milling CNC Machining