Carbide Hobbing Technology for Automotive Gears.

2015

Precision Engineering

a b s t r a c tHigh-accuracy gears are necessary to ensure the strength and silence of compact geared motors. Heattreated surface-hardened small gears are employed in the reducer of a compact geared motor. The heat treatment causes distortion, which deteriorates the gear accuracy. To remove this distortion, surfacehardened small gears are rehobbed with a carbide hob. The rehobbing makes a tool mark on the gear tooth surface. This tool mark leads not only to strength deterioration of the tooth surface, but also vibration and noise. Therefore, a surface finishing method that eliminates the tool mark is required. However, it is difficult to finish surface-hardened small gears. This study proposes a tooth surface finishing method for a surface-hardened small gear. The method employs a gear-shaped tool composed of alumina-fiberreinforced plastic (ALFRP) and a surface finishing device with an oscillation/traverse system. The proposed method was used in an experiment to remove the tool mark on the gear tooth flank of a surface-hardened small gear rehobbed by the carbide hob. The effectiveness of this method was verified. In addition, the processing mechanism of the ALFRP gearshaped tool was analyzed by observing the tool and the chips.

Section: Introductionmentioning

confidence: 99%

Surface finishing method for tooth flank of heat-treated surface-hardened small gears using a gear-shaped tool composed of alumina-fiber-reinforced plastic

Fujisawa

2015

Precision Engineering

“…It has great advantages in increasing productivity and decreasing manufacturing cost (1), (2) . Dry hobbing, however, often causes problems such as the chipping of the cutting edge of a hob or the coarse tooth flank of a manufactured gear.…”

Section: Introductionmentioning

confidence: 99%

“…The same remedy or/and the selection of an adequate coating and material of the hob can improve problems concerning item (3). However, a remedy for problems concerning item (1) has not been found because of complex mechanism of hobbing and chip generation.…”

Section: Introductionmentioning

confidence: 99%

Method of Preventing Cutting Edge Failure of Hob Due to Chip Crush

Sumi²,

Kubo

2004

JSME Int. J., Ser. C

Self Cite

Dry hobbing has great advantages such as its environmental friendliness and its ability to reduce manufacturing cost. Dry hobbing, however, often causes failures of the cutting edge of a hob or problems on the surface quality of the tooth flank of a manufactured gear. The pinching and crushing of generated chips between the cutting edge of a hob and the tooth flank of a work gear is considered to be a major cause of such problems. A simulation method of cutting using a hob was reported. In this report, the simulation is applied to solving the industrial problems of dry hobbing. The simulation clarifies the mechanism of cutting edge failures. The "distance of single-edge cutting" of a hob tooth is proposed to be an index of pinching and crushing of chips. Factors influencing this index are investigated and fundamental countermeasures against pinching and crushing are shown. This method has been applied to solving problems in the mass production of automotive gears, and good results were obtained.

“…Three types of chip crush between hob cutting edge and work gear tooth flank are possible: (1) crush during generation of chip, (2) crush of chip flying after its generation, (3) crush of chip stuck on hob tooth after a rotation of hob (Ref. 3).…”

Section: Introductionmentioning

confidence: 99%

“…The same remedy and/or selecting of adequate coating and material of hob somewhat improves item (3). But the remedy for item (1) has not been clarified because of the complicated mechanism of hobbing and chip generation.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Hobbing for Analysis of Cutting Edge Failure Due to Chip Crush

Volume 4: 9th International Power Transmission and Gearing Conference, Parts a and B

Sumi

Kubo

2003

Self Cite

There are great advantages in dry hobbing not only for friendliness on the environment, but also for increasing productivity and for decreasing manufacturing cost. Dry hobbing, however, often causes failures of cutting edge of hob or problems about the surface quality of tooth flank of manufactured gear, which have not been of problem in case of hobbing with cutting oil. Pinching and crushing of generated chips between cutting edge of hob and tooth flank of work gear is considered to be a major cause for those problems. In this report, a calculating method of trace of each cutting edge of hob relative to work gear is compiled to simulate the clearance between cutting edge of hob and tooth flank of work gear. The thickness and form of generated chip and its movement on rake surface of hob tooth during hobbing process can be clarified by consulting the result of this simulation. Probability of pinching of chips between cutting edges of hob and tooth flank can be evaluated by dealing with the relation among the position and width of clearance, chip thickness and direction of chip movement, which contributes to successful dry hobbing.