50钢凸轮轴零件最终热处理工艺设计(2)
Requirements: the camshaft bearing gear cam technology, the depth of hardened layer of 2-6mm, length is 890mm, the hardness of 58-62HRC.
The camshaft is an important part of engine valve system, rotation of the camshaft is driven by the crankshaft, to ensure that each cylinder inlet,exhaust valve follow a time switch, ensure adequate ventilation of engine,the intake valve and exhaust valve, to ensure lasting combustion chambersealing, the engine is sustainable and good power. In addition the camshaftis also used to drive the combustion system parts.
In this design, the specific design of the current frequency, power, the quenching area, sensor, quenching and quenching equipment, cooling andtempering, tempering equipment etc.
Principle to determine the frequency of current:
(1) the primary principles of current frequency is selected through heating.
(2) to high electrical efficiency.
(3) in the workpiece material diathermanous, heating time is the shortest.
At the same time, according to the formula F best =600/ δ x ², we got thehome current frequency range 7222-15000Hz, and select the current frequency 10KHz as the current frequency of this design.
The electric power induction heating the workpiece in the unit area of theabsorption ratio of power is. The equipment for equipment than the poweroutput power and spare parts at the same time the heated area ratio. Than the power of choice by the depth of the hardened layer current and the frequency required to decide. In the choice of specific power, need to consider the following factors: for shaft parts surface hardening, when the quenching area is smaller, the shape is simple, hardening layer is thin, the original microstructure is fine, parts and materials for the medium carbonlow-alloy steel, parts of the production batch is larger, can choose specific power range. On the contrary, it should be the choice of the lower limit.Through calculation, we select the equipment than power is P = 3kW/cm2.
Considering the effect of original microstructure surface before quenchingand heating speed, each kind of steel with a heating specification for the best. And for the design of parts, heating method is used for simultaneousheating method. Cam when quenching, at the same time heating andheating process does not rotate. In the bearing gear quenching by rapidscanning, continuous heating, the workpiece rotation, to achieve uniformheating effect.
And the heating temperature induction quenching at 920 ℃, the heating rate of 120 ℃ /s.
The heating time bearing block for 6S, heating and heating. The small cam10s of heating time, heating and heating. The large cam 4S of heating time,heating and heating.
But according to calculation formula of cooling time: tc= (1~2) tH.
Cooling time cam profile for tc=6-12s. The large cam cooling time selection ofthe design for 8s.The cooling time small cam profile for tc=10-20s. The small camcooling time selection of the design for 15s.
The cooling time bearing block for tc=6-12s. Bearing cooling time selection of the design for 8s.
Design of cooling medium with tap water. Because the water is low cost, canobtain better economic benefit in the production.
In this design, the design of inductor and the most complex, the sensordesigned well, can meet the technical requirements to ensure product quality, low energy consumption, long service life, reasonable cost. The selection of sensors according to the main factors shape workpiece shapeand the selection of heating methods to determine.
The final design of the inductor size as follows: sensor cam profile sensorheight 22mm, bearing retainer sensor height of 35mm induction coil is made of 1.5mm thick wall copper tube, coil diameter is 67mm. The inductor and the workpiece gap size is 3mm.
Quenching equipment used for BPS200/8000. The rated power is PE = 200kW, and use the vertical double camshaft quenching machine tool. The tempering equipment for JHJ-75-6 well type tempering furnace.