A kind of cold-drawing method of special-shape bearing Steel Bar During
Technical field
The present invention relates to a kind of manufacture method of metal bar, relate in particular to a kind of cold-drawing method of bearing bar.
Background technology
GCr15 chromium bearing steel is one of main material of making each class bearing.The GCr15 bearing steel is used to make rolling element or the axle sleeve on motor, lathe, tractor, the mine universal machine.The cold drawn bearing steel bar of GCr15 has round steel bar, equilateral hexagonal special-shape bearing Steel Bar During, and unequal-sided special-shape bearing Steel Bar During.The single roll bearing is a kind of in the bearing class, is widely used in the equipment such as textile machine, food machinery, harvester, washing machine, lathe.Employed rolling element in the single roll bearing is exactly a kind of in the special-shape bearing Steel Bar During.
The special-shape bearing Steel Bar During that rolling element uses in the single roll bearing, its cold-drawn special-shape bearing Steel Bar During " surface quality " must reach: defective such as must not there be crackle, folding in the surface, scab, pit, more than the tolerance grade h7, decarburized layer≤0.03mm, cold drawn back linearity≤1mm/m.
At present, the preparation of cold-drawn special-shape bearing Steel Bar During of single roll bearing, its conventional production process flow process is: smelting+refining+vacuum outgas ingot heat is sent (or cold sending) → breaking down cogging → rolling coiling (hot rolling+spheroidizing heat treatment) production → cold machining process (cold drawn → aligning → polishing → cold drawing molding) → check and warehouse-in.Wherein cold drawn concrete technology is: steel are passed from cold drawn mould, utilize pulling capacity to make steel produce plastic deformation, reach required size.
Adopt the single roll bearing profiled bar of the cold-drawing method production of above-mentioned special-shape bearing Steel Bar During, major defect is: the lumber recovery of profiled bar is lower, only be about 58%, finished surface often occur plucking phenomenon (grinded bar because the raising of surface smoothness, the adhesive force of moistened surface agent descends, after cold drawn distortion heat release, lubricating system is destroyed, and cold drawn bar and cold drawn mould stick together, and interlock produces plucking); In addition, the machete bending that can't align appears in cold drawn bar is (in plastic history, the flow direction of metal is to move by the minimum drag direction, in the cold drawing process when the round steel bar becomes profiled bar, the machete bending that can't align has appearred in the inequality that stress distribution occurred, and linearity does not reach requirement, aligning buckling phenomenon after the generation moulding), cause the bar linearity can't reach requirement.
For above-mentioned defective, prior art adopts the baking process of coating lime to eliminate the plucking phenomenon on bar surface, and steel is increased the drafts method during by aligning and eliminate the machete bending, but all can not reach the requirement of ordinary production.
Summary of the invention
The cold-drawing method that the purpose of this invention is to provide a kind of special-shape bearing Steel Bar During, it is used for the production of single roll bearing with special-shape bearing steel profiled bar, use this method that the special-shape bearing Steel Bar During is carried out cold-drawn and should avoid " plucking " that take place in its Cold Drawing Process and " machete is curved " phenomenon, thereby improve the lumber recovery of finished product, satisfy of the production requirement of single roll bearing with cold-drawn special-shape bearing Steel Bar During.
According to the foregoing invention purpose, the invention provides a kind of cold-drawing method of special-shape bearing Steel Bar During, it comprises the following steps:
(1) surperficial peeling: bearing steel disk circle is carried out surperficial peeling, remove blemish, skin decarburization; Because the online shot-peening method that existing continuous drawing machine adopts can be damaged the bearing steel surface, therefore in order to cooperate the technical program, the inventor has adopted surperficial peeling technology, through the circle of the bearing steel disk after this peeling PROCESS FOR TREATMENT, defectives such as its surperficial non-scale, very bright and clean, be better than general bearing steel disk circular surfaces quality at present greatly.
(2) surface preparation: after will bearing steel disk circular surfaces pickling through peeling, epithelium film and lubricant; This step is in order to reduce the coefficient of friction in the drawing process as far as possible, the resistance of deformation during with the reduction drawing.
(3) cold drawn preceding road distortion: adopt drawbench just bearing steel disk circle be out of shape in preceding road and cold drawnly in the cold drawn mould be special-shaped dish circle, preceding road cold-drawing deformation is controlled at 7-10%, cold-drawing speed is smaller or equal to 80m/min, and the semi circular surface that described preceding road is out of shape cold drawn mould is provided with up;
(4) recrystallization annealing: abnormal shape dish circle is warming up to 680-700 ℃, is incubated cooling after 4-6 hour;
(5) annealing rear surface preliminary treatment: after abnormal shape coiled the circular surfaces pickling, epithelium film and lubricant;
(6) cold drawing molding: adopting drawbench is the profiled bar finished product with abnormal shape dish circle cold drawing molding in the cold drawn mould of moulding, cold-drawing deformation in this step is controlled at 30-45%, cold-drawing speed is smaller or equal to 40m/min, and the semi circular surface of the cold drawn mould of described moulding is provided with up.It is that the inventor is carrying out on the basis of plasticity index check and analysis bearing steel disk circle that cold-drawing deformation is controlled at 30-45%, in conjunction with cold deformation amount theory, and simultaneously in conjunction with the correction value that obtains by a large amount of tests, and the result who finally obtains.
Preferably, the cold-drawing method of described special-shape bearing Steel Bar During also comprises step (7) aligning: usage level axle and vertical axis are aligned the profiled bar finished product, control its linearity≤1mm/m.
Preferably, control surface roughness Ra in the described step (1)≤0.8 μ m.
Preferably, adopt the sulfuric acid acid solution to carry out pickling in described step (2) and (5), the composition of described sulfuric acid acid solution is: concentration is the sulfuric acid of 15-20wt%, concentration is the sulfatase inhibitor of 3-6wt%, concentration is the ferrous sulfate smaller or equal to 50g/L, pickling temperature is 50-70 ℃, and the pickling time is 5-8min.
Preferably, the total acidity of film agent is 35-45 described in described step (2) and (5), and free acidity is 5.5-7.0, and the film agent dipping temperature is 70-85 ℃, and dip time is 5-10min.
Preferably, the dip time of lubricant is 4-5min described in described step (2) and (5), and dipping temperature is 75-85 ℃.
The present invention carries out cold-drawn by adopting technique scheme to the special-shape bearing Steel Bar During, and the different in nature rod product that makes it existing explained hereafter has following advantage:
1. the phenomenon of finished product " plucking " " bending " can be avoided substantially, and lumber recovery is greatly improved, and can reach more than 88%;
2. finished surface is processed the requirement that just can directly reach rolling element without any form, has guaranteed the size conforms designing requirement of profile shapes, only after the modified processing of need, just can be directly used in the installation bearing;
3. the operation expense descends significantly, and finished product output and quality all can be guaranteed.
The specific embodiment
Carry out cold-drawn production according to the following step:
(1) bearing steel disk circle is carried out surperficial peeling, remove blemish, skin decarburization: the feed speed of setting the peeling cutter is 25-30m/min, the cutterhead rotating speed is controlled at 2800RPM, use the polishing machine polishing then, polishing machine rotating speed≤240-250RPM, control surface of polished roughness Ra≤0.8 μ m.
(2) surface preparation: sulfuric acid washing → bath → last D3-D35 film agent and lubricant → dry up.The composition of sulfuric acid acid solution is: concentration is the sulfuric acid of 15wt%, and concentration is the sulfatase inhibitor of 5wt%, and the concentration of ferrous sulfate is 50g/L; 55 ℃ of acid liquor temperatures, pickling time 6min.D3-D35 film agent total acidity (TA) is 40, and free acidity (FA) is 6.0,75 ℃ of dipping temperatures, dip time 8min.Lubricant is a LS-2 solution, and its solubility is 6wt%, and the lubricant impregnation temperature is 4-5min, and dipping temperature is controlled at 75-85 ℃.
(3) adopt drawbench just bearing steel disk circle be out of shape in preceding road and cold drawnly in the cold drawn mould be special-shaped dish circle: dish circle → uncoiling and de-distortion → drawing → online collection that twists.Preceding road cold-drawing deformation is controlled at 7-10%, and cold-drawing speed is smaller or equal to 80m/min, and the semi circular surface that preceding road is out of shape cold drawn mould is provided with up.Preceding road is out of shape cold drawn mould inner surface does not have defectives such as sand holes, scuffing, pit, ring-shaped groove, carries out essence with emery grinding grease and throws, and its surface smoothness reaches the minute surface requirement.The physical dimension that preceding road is out of shape cold drawn mould is: 60 ° of inlet angles, and 36 ° of Lubricanting cones, 16 ° of Drawing cones, calibrating strap 3~5mm goes out 60 ° of prostomums, and its material is YG8.Twist to collect and undertaken by two online bending roll units, the dish circle external diameter after the bending is at 1000-1200mm, and internal diameter is 800-1000mm.Preceding road cold-drawing deformation and the cold-drawing speed of embodiments of the invention 1-5 are as shown in table 1.
(4) recrystallization annealing: because bearing steel adopts certain deformation amount technology by the cold drawn one-tenth of circle when special-shaped, the skewness of steel circumferential stress is relatively big, and steel produce the inhomogeneities of work hardening and circumferential stress can't carry out follow-up processing.Therefore, the dish circle after cold drawn can take recrystallization annealing to handle, and to eliminate cold-drawn stress, reduces hardness, recovers plasticity, carries out cold drawn then again.
Profiled bar in the various embodiments of the present invention after cold drawn is annealed at strong convection nitrogen hydrogen protective atmosphere bell furnace, and protection gas is N
2+ AX (mist of nitrogen and hydrogen), nitrogen dew point≤-60 ℃; AX gas dew point≤-60 ℃; Oxygen content :≤5ppm.Abnormal shape dish circle is warmed up to 680-690 ℃ with stove, is incubated band cooling dome cooling after 6 hours.
(5) carry out pickling and lubricated according to the described technology of step (2) again after the annealing.
(6) adopting drawbench is the profiled bar finished product with abnormal shape dish circle cold drawing molding in the cold drawn mould of moulding, and the cold-drawing deformation in this step is controlled at 30-45%, and cold-drawing speed is smaller or equal to 40m/min.Simultaneously, by the trunnion axis of adjustment mould and the angle of vertical axis, keep making progress through the disc of cold drawn rear bearing steel profile shapes.Cold-drawing speed in the total cold-drawing deformation of embodiments of the invention 1-5 and the step (6) is as shown in table 1.The physical dimension of the cold drawn mould of moulding is: 60 ° of inlet angles, and 36 ° of Lubricanting cones, 14 ° of Drawing cones, the calibrating strap shape is the special-shaped final size shape of finished product, length is: 3~4mm, go out 60 ° of prostomums, its material is YG8.
(7) finished product on-line straightening usage level axle (X-axis) and the two-way aligning of vertical axis (Y-axis), linearity≤1mm/m.
Table 1
Each finished product among the embodiment 1-5 is appearance " plucking " and " machete is curved " phenomenon, and profiled bar finished product hardness is: HRB 255-260; Decarburization<0.03; Spherodized structure: 2.0 grades, meet product specification and requirement fully.
Be noted that above enumerate only for specific embodiments of the invention, obviously the invention is not restricted to above embodiment, many similar variations are arranged thereupon.If those skilled in the art all should belong to protection scope of the present invention from all distortion that content disclosed by the invention directly derives or associates.