Roll nitrogen of linear slideway ion turns metabolic control

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The general function component that rolls linear slideway is machinist job, its quality affects the precision of mechanical equipment and service life directly, because this requirement slideway has tall wearability and dimension stability. Although can obtain tall hardness and wearability,ionic nitrogen changes slideway, but because nitrogen is changed,was out of shape in the past bigger, make slideway ion nitrogen changes commercialization to be restricted. Pass a test, find out slideway ion nitrogen to change metabolic rule, adopt relevant technology measure, make the slideway of length 760 Mm, after ionic nitrogen is changed, the technical condition that can make extreme deviation of bent of slideway bottom tool reference plane and extreme deviation of bent of side tool reference plane satisfy precision of the 5 that sets about document, 6 class. Introduce concerned test case as follows now. One, slideway norms, with material and technical requirement experiment slideway model has two kinds, namely LG25, × of 23 Mm of over all dimension 22.

5mm × 760mm; LG30, × of 28mm of over all dimension 27.

5mm × 760mm. Slideway is shown 1 times like the graph, it is LG25 dimension without bracket number among them, the number inside bracket is LG30 dimension. Ionic nitrogen changes slideway to be steel of 38Cr MoAl A with material, semifinished product is hot-rolling great ability, the diameter is 40 Mm and 50mm respectively, classics cutting machines figuration. The technical condition that slideway nitrogen changes: 650HV of exterior hardness ≥ , nitrogen changes layer deepness ≥ 0.

4mm, 2 class of brittleness ≥ , the law of check proved recipe of deflection and allow difference see graph 2, picture 3 with subordinate list. 2, beforehand semifinished product of heat treatment slideway chooses two kinds beforehand heat treatment craft, namely anneal and shift are simple. Anneal craft: 2h of heat preservation of 870 ℃ , furnace is cold give furnace air below to 500 ℃ cold. Hardness ≤ 229HBW. Shift is simple: Heat preservation of ℃ of 940 of 930 ~ 1.

5h, oily Leng Cuihuo; Subsequently 3h of temper of 680 ℃ , air is cold. 28HRC of ~ of hardness 25. Classics beforehand the slideway semifinished product of heat treatment, mix in groove of side of the plane that finish, mill after getting installing hole to wait for rough machining working procedure, undertake going for the first time stress anneal. In chamfer of steel wire of groove of dig of essence of life, dig and kibble the finish machining working procedure such as 4 plane is finished hind, reentry goes the 2nd times all right stress anneal. Go stress anneal craft (homogeneous phase of two anneal craft is the same as) : 2h of heat preservation of ℃ of temperature 650, furnace is cold give heat below to 250 ℃ . 3, slideway ion nitrogen changes test result to reach its to analyse (the vertical ion nitrogen that 1) ionic nitrogen changes craft standard to change used device to be electric current of rated output dc to be 30A for slideway nitrogen turns heat. Nitrogen changes temperature and time to be respectively: 530 ℃ / ℃ of 8h, 550 / ℃ of 15h, 550 / 22h and 560 ℃ / 10h. (Hardness of the organization that 2) nitrogen changes a layer, surface and ℃ of 530 of classics of steel of hardness echelon 38CrMoAl A / after 8h ionic nitrogen is changed, ooze layer organization is reached by the watch in ordinal ε of the → that it is ε + α of γ ′ → + organization of core of γ ′ → . Its feature is: Most surface layer ply 0.

02 ~ 0.

Lubricious compound layer of 03mm Bai Liang, namely ε photograph. Rely on the second surface layer of white bright lubricious compound layer closely, occurrence nervation is organized, ply 0.

01 ~ 0.

15mm, photograph composition is ε + γ ′ . In the future is diffusion layer, photograph composition is α + γ ′ . Go to again in it is core organization. Still can see in metallographic analysis, the metallographic organization before nitrogen is changed and the content that the nervation after nitrogen changes craft parameter to nitrogen organizes have bigger effect. Anneal organization changes the tendency that nervation organization forms in the process to pledge than tone the organization is gotten greatly in nitrogen much, and nitrogen changes temperature taller, nitrogen changes time to grow more, all promote the formation of nervation organization. Classics is different beforehand the 38CrMoAl A steel of heat treatment changes 22h at ionic nitrogen of ℃ of 560 of 540 ~ , if the graph is shown 4 times,hardness distributings along what nitrogen changes a layer. By the graph 4 can see, after be being handled via afore-mentioned craft, nitrogen changes a deepness to maintain in 0.

50mm above. The hardness profile that nitrogen changes a layer and beforehand heat treatment is concerned. In identical ionic nitrogen chemical art condition falls, anneal condition slideway is made an appointment with 0.

The outside layer hardness of 2mm is taller than mix qualitative condition, from the surface 0.

1mm place, the 800HV100 of hardness prep above of anneal condition, and the hardness that moves qualitative condition here maintains 650HV100 only; From the surface 0.

15mm place, the hardness of anneal condition still prep above 700HV100, but the hardness that moves qualitative condition here already under 600HV100. 4, the standard is narrated to undertake to slideway ionic nitrogen is changed before ionic nitrogen changes slideway metabolic regularity to press. Nitrogen changes slideway be out of shape the rule: Of A of bottom tool reference plane be out of shape bigger, assume raised position; B of side tool reference plane is out of shape lesser, curve a quantity to be less than 0.

1mm. A face deflection and slideway are sectional dimension and heat treatment (include beforehand heat treatment) the element such as craft parameter is concerned. (1) slideway is sectional size is larger, after nitrogen is changed be out of shape smaller for example, LG25 slideway makes an appointment with the cut area ratio of LG35 slideway big 50 % , both all handle via anneal before nitrogen is changed, via ion of ℃ of temperature 530 subsequently nitrogen changes 8h. After nitrogen is changed, of face of LG35 slideway A the biggest curve a quantity for 0.

245mm, and sectional of face of A of small LG25 slideway the biggest curve a quantity to be 0.

489mm, namely the slideway with the smaller than cut area deflection of the slideway with large area of the cut after nitrogen is changed reduced 1 times. Of cut area increase, mean slideway stiffness (cut area and product of stretch model volume) increase. Accordingly, counteractive outside force (the constituent stress that nitrogen changes a process to arise and thermal stress) the ability of deformation increases, the slideway with this cut larger area is in reason nitrogen changes a process to be out of shape mediumly lesser. (2) beforehand heat treatment parts to pledge via anneal and attune to metabolic influence beforehand the LG25 of heat treatment slideway, fall in identical craft parameter (550 ℃ / 15h) undertakes ionic nitrogen is changed. Result discovery, no matter be the slideway with anneal or simple shift, be out of shape to what nitrogen changes slideway B face without how old influence, curve a quantity to maintain in 0.

050 ~ 0.

Inside 060mm limits, but to A face be out of shape the impact is very big, of face of the A after anneal slideway nitrogen is changed opposite the biggest curve a quantity to already was achieved 0.

4mm, and move qualitative slideway curve a quantity bigger, amount to unexpectedly 1.

8 ~ 1.

9mm. Beforehand heat treatment is so apparent to metabolic influence, with beforehand the stability that heat treatment organizes is concerned. Anneal organization is adjacent organize at the balance, in nitrogen organization of the matrix in changing a course is in relatively steady state, of the slideway after reason nitrogen is changed be out of shape lesser. Tone pledges slideway differs, its matrix organizes temper to all alone family name body is in metastable condition. Although nitrogen changes the temper temperature when temperature pledges under tone, also under go the temperature of stress anneal, but long heat preservation course is changed in nitrogen in, carbolic atom obtains energy to undertake diffusing gathering, strive transfers to balance position. This one process compares anneal to be gotten strongly apparently to the change of slideway stress condition much, accordingly, move what qualitative slideway nitrogen changes to be out of shape comparing anneal slideway is the circumstance in anticipation greatly. (3) nitrogen changes time to grow more, be out of shape bigger nitrogen changes time to be opposite of B of side tool reference plane be out of shape without apparent effect, nitrogen changes time to be as long as 22h, of B face be out of shape relatively still be less than 0.

1mm. Nitrogen changes time to be affected to metabolic of A of bottom tool reference plane very big however, change the extension of time as nitrogen, of A face be out of shape bigger, its exceed 1mm (to see graph 5) even relative to deflection. Well-known, nitrogen changes time to grow more, the deepness of azotic atom infiltration is deeper, the addition that accompanies volume of surface layer unit is bigger, because of this slideway be out of shape also influence the growth of time along with nitrogen and increase. (4) local nitrogen changes pair of metabolic influences to be able to see from afore-mentioned test results, all sorts of factors are not quite obvious to influence of metabolic of B of side tool reference plane. And A of bottom tool reference plane is different, any element has a bit slight and fluctuant, very intense to its metabolic influence, the asymmetry sex of this and slideway nitriding face has affinity. In the graph 1 cross section makes perpendicular OP and OQ through center O. OP controls slideway departure, b of side tool reference plane and figure of its corresponding another lateral geometry say relatively roughly. Accordingly, the change of effect of the bulk in the process and stress condition is spent in nitrogen, two symmetrical faces can offset each other, of face of reason comparing B be out of shape lesser. The circumstance that see OQ part slideway up and down now again how? On OQ line half have the groove, late head screw that has installation screw () of big head screw; Below OQ line half part has A of tool reference plane of alveolus screw, bottom to reach its only A face retreats knife chamfer. Bottom gets on OQ line half watch area ratio greatly much. The symmetry photograph of A face and B face is compared, both form sharp contrast. Because two parts asymmetry falls on slideway quality, the addition that nitrogen changes on slideway half nitrogen to turn layer unit volume is bigger than below half, below the aspect expansion ratio that gets on half namely half big. On half body expands get central boycott is more intense than below half also, the stiffness that adds on half again is smaller than below half, the master piece outside sufferring uses next is out of shape to come more easily. What if the graph is shown 2 times,appear is intense bend. Be based on A of bottom tool reference plane to be opposite of whole slideway be out of shape removing dominant to affect action, and of A face be out of shape is what by slideway asymmetry of fluctuation surface area causes. So if should reduce nitrogen to change slideway to be out of shape, should decrease " asymmetry " the influence of the element. another surface of A face and its place correspondence screen rises undertake nitrogen is changed, the nitrogen after slideway nitrogen is changed changes a layer distributing to basically be in symmetrical condition, this is helpful for those who reduce nitrogen to change slideway be out of shape. Test result makes clear, the local nitrogen of afore-mentioned measure is changed to reducing guide be out of shape, especially of A face be out of shape is very effective. For example, LG30 of 38CrMoAl A steeliness slideway (beforehand heat treatment attune pledges) , of face of the A after ionic nitrogen is changed the biggest curve a quantity for 0.

17mm, the technology that satisfies the 5 class precision that provides about document asks. 5, epilogue (nitrogen of 1) slideway ion changes be out of shape have apparent regularity, it is arch case (pursue 3 photographs to detecting platform) . Metabolic is main nitrogen changes asymmetry place to cause the account. (2) uses local nitrogen to change a way, reduce nitrogen to turn the asymmetry sex of the face, can reduce what nitrogen changes slideway to be out of shape significantly. (3) ionic nitrogen changes slideway to be out of shape small, it is undertake handling below vacuum condition, change around surface quality to do not have apparent effect to nitrogen, the nitrogen of slideway is changed can arrange undertake after essence of life is ground, can make sure slideway has deeper nitrogen to change a deepness so. CNC Milling CNC Machining