Undertake the accurate grinding of face of outline of cam of dambered surface graduation with CNC Milling

Place a head 2.

Wheelhead 3.

Tip 4.

Cam semifinished product 5.

Core axis 6.

Dividing head pursues the helicoid that sketch map of cam of graduation of 1 dambered surface is one space to cannot spread out as a result of face of outline of cam of dambered surface graduation (3) seeing a picture, country is at present right the treatment of this spare parts, still stay in numerical control to shape milling + long grind on constructional craft level. The main drawback of this craft is precision workload of make repairs and supply replacements of low, spare parts is big, form batch to produce hard, treatment quality also gets assuring hard. The way that abroad settles is to use machining center of 5 coordinate grinding to undertake machining, but this program installation cost is huge, finished cost is very high also, user of great majority of its price country is accepted very hard. For this, we designed QMT model short outside wheelhead of pneumatic of the high speed that extend end (patent application date 95218369.

7) , its installation is on the main shaft of special CNC Milling (2) seeing a picture, use get together emery wheel of composite material long life is opposite brilliant successfully face of outline of cam of dambered surface graduation undertook grinding is machined, its are main the principle is to use QMT model short outside wheelhead of pneumatic of the high speed that extend end will increase rotate speed of machine tool main shaft, the rotate speed when grinding of made contented high speed asks. If machine tool parameter is adjusted proper, its effect is close to numerical control grinder, enlarged the scope of application of CNC Milling effectively, turn into CNC Milling numerical control grinder. Graph face of outline of cam of graduation of 2 dambered surface processes signal experiment of craft of grinding of face of outline of 2 grinding method and cam of graduation of dambered surface of main craft parameter is the XK5001 in research center of engineering of CAD/CAM of institute of northwest light industry undertake on special CNC Milling. Will self-restrained QMT short outside wheelhead of pneumatic of the high speed that extend end loads this machine tool to main shaft carries a department and try to secure directly, use newest development get together brilliant emery wheel of composite material PCBN (replace milling cutter) do grind, press program of NC of work out of correction sine motion curve, undertake grinding to face of outline of cam of dambered surface graduation, grinding contrail is cannot exhibit dimensional curved surface, refer to attached drawing 3. As a result of QMT model short outside wheelhead of pneumatic of the high speed that extend end is it is dynamical drive main shaft in order to compress air to make high speed rotate, drive emery wheel to undertake grinding, it serves as refrigeration with compressing air, cooling fluid need not be added in grinding. In whole grinding area, use minim oily mist to envelop, will dominate field of grinding area temperature, have dustproof effect. Because get together,do not have fall off, scrap proportion flies upwards not easily greatly, whole grinding process does not have dust pollution basically. The feature of face of odd side outline that the graph draws in 3 hypostatic modelling is main craft parameter is as follows: Emery wheel material is qualitative: Get together nitrogen of brilliant cubic metre changes size of boracic PCBN; emery wheel: Diameter of emery wheel of 120 ～ 140; : 10mm; Working atmospheric pressure: 0.

3 ～ 0.

Speed of 6MPa; emery wheel: 25000r/min; feed speed: (9 ～ 60)r/min; installs means: Handle of awl of Mo Shi 3# ; Workpiece hardness: Cooling condition of HRC60 ～ 62; : Air cooling; Environmental temperature: 18 ℃ . Test specimen is counted for graduation 10 graduated cam of dambered surface graduation, workpiece material is 20CrMnTi, body of nitrogen of carbon of the classics after thick mill in all the temper by dipping in water after ooze comes forcedly HRC60 ～ 62. Use a few lubricating oil are added in compressing air, after pulverization, direct gush cover undertakes in the method of emery wheel and grinding area refrigeration and fall dirt. Surface roughness of surface of outline of cam of 4 tests result (0.

6 ～ 0.

8)µm; (0.

006 ～ 0.

125)mm;(0.

002 ～ 0.

038)mm; cam chamfer is wide outline of cam of on size error keeps precision of paragraph of graduation of static state of jumpy cam mechanism to see a table 1. Express graduation of static state of 1 cam mechanism to check record data to express 　 surface roughness value is 4 results analysis and the cam outline surface after discussion grinding (Ra0.

6 ～ Ra0.

8)m, already achieved a design given requirement. If choose 210 ～ 230 emery wheel, the value can amount to exterior surface roughness (Ra0.

2 ～ Ra0.

4)m, this already can satisfy its the requirement of graduation of high speed, high accuracy to exterior surface roughness. Cam chamfer is wide on size error: Already achieved 0.

01mm left and right sides, one times taller than milling dimension precision above, better land satisfied the requirement on clench the teeth of drive of cam index mechanism. Stay from cam paragraph jumpy look, already achieved (0.

002 ～ 0.

038)m, this and data of record of test of graduation of cam mechanism static state express photograph be identical. By the watch medium fore-and-aft numerical value looks, the cam after grinding keeps precision to be able to be stabilized in 1.

5" left and right sides, this index that shows cam already achieved what the developed country such as beautiful, day makes to be less than 0.

The standard of 005mm. The transverse numerical value in the watch mirrors those who give driven plate to make precision. And closely related the jumpy precision of the stability that graduation outputs and roller. Look from dustproof effect, atmosphere of minim oily mirage is formed after a few lube, made pulverization is joined in compressing air, envelop will control grinding dust in emery wheel and whole grinding area, the method is simple and the effect is distinct. Oneself of PCBN emery wheel is not had almost fall off, dirt bit is little, grind the scrap below to submit fiber form with it, fiber of this kind of iron flies upwards not easily, envelop plus oily mist, in the area with made very small on workbench face concentration, successful settlement the difficult problem that arrive because of grinding bits to distribute on machine tool slideway and affects life of machine tool work. Look from the graduation of field of grinding area temperature, use compress air to cool (belong to dry grind) the effect is distinct. When environmental temperature is 18 ℃ , the temperature rise of emery wheel is maintained control in 27 ℃ (workpiece temperature rise is 22 ℃ ) only. Because the temperature of grinding area gets be controllinged effectively, won't produce grinding burn, won't make because of grinding overheat workpiece is out of shape more and affect grinding precision, grinding of this successive to high accuracy space contrail comes it is important to be. Additional, PCBN emery wheel works the way when grinding to grinding force and tangential grinding force Fn, Ft all is less than wet grinding, and Zw of metallic excision rate is more than wet grinding. This also is the another main factor that chooses air cooling to do wear work. 5 conclusion use He Jujing of wheelhead of pneumatic of high speed of general CNC Milling, configuration cubic nitrogen turns boracic emery wheel, undertake numerical control grinding to face of outline of cam of dambered surface graduation, its method is simple and easy and feasible, and cost is low. Craft of grinding of numerical control of curved surface of this kind of airspace, the grinding of the hard curved surface of temper by dipping in water that already can satisfy general precision asks, if facilities is excellent, its grinding effect can be achieved or be close to the treatment precision of center of numerical control grinding. Can popularize its completely application to arrive on machine tool of other numerical control the grinding that has dimensional curved surface. CNC Milling CNC Machining