• Journal of the korean Society of Automotive Engineers
• /
• v.15 no.3
• /
• pp.120-125
• /
• 1993

The surface roughness of workpiece is reduced during spark-out. The reduction of roughness is a benefit of spark-out, but spark-out lowers productivity. The characteristics of spark-out are different to those of plunge grinding to which feed is applied. This difference is due to overlapping cutting during spark-out. Effect of spark-out is in proportion to volume of grain wear. This phenomenon is due to different overlapping area. Dressing interval can be enlarged by spark-out, when volume of grain wear is large. In this study, the characteristic of spark-out was studied by spark-out obserbation in various grinding conditions. For this purpose thrust force, spark-out time and surface roughness of workpiece were experimentally investigated in various grinding conditions.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.6
• /
• pp.52-58
• /
• 1996

This paper described on the effect of residual stocks in internal grinding of tungsten carbide materials in order to improve the grinding efficiency as well as grinding accuracy. Through the fundamental investigation is carried out for tungsten carbide materials using electroplated diamond wheel, the residual stock after grinding process is effective to the grinding efficiency. The obtained results are as follows: (1) Under the depth of cut(t) is constant and decreasing the workpiece velocity(Vw), the residual stock after grinding is increased, but the difference is little less than the difference by table speed. (2) Increasing the wheel velocity, the residual stock after grinding is decreased. Therefore in order to minimize the residual stock, the wheel velocity should be increased as far as possible. (3) The surface roughness and out-of roundness increased with depth of cut and table speed, and decreased with wheel velocity, but it may as well adopt as much as possible under the dimensional tolerance which is required for high efficiency grinding. (4) In order to remove residual stock, the spark-out grinding shoule be done, and it also can be improved about 20~25% throughout spark-out grinding, and the number of optimal spark-out times were within 10 times.

• Fire Science and Engineering
• /
• v.29 no.3
• /
• pp.43-47
• /
• 2015

Water mist was sprayed on small compartment areas filled with smoke that formed from two different combustibles. The water-mist injection pressure and time were varied, and changes in the light extinction coefficient were measured over time. The smoke removal effect was analyzed with a light sensing smoke meter in different experimental conditions. Using the meter, the changes in smoke density were converted to changes in DC voltage over time to obtain the changes in the light extinction coefficient. The water mist was more effective in eliminating the smoke formed from glowing compared to flaming combustion. The smoke removal effect was significantly better with greater injection pressure and injection time.

• Fire Science and Engineering
• /
• v.28 no.6
• /
• pp.28-34
• /
• 2014

Two kinds of new piperazinomethyl-bis-phosphonic acid $M^{n+}$ ($PIPEABPM^{n+}$) were synthesized and their combustive properties of Pinus rigida plates treated with $PIPEABPM^{n+}$ were tested in comparison with the previously synthesized chemicals. Pinus rigida specimens were painted in three times with 15 wt% $PIPEABPM^{n+}$ solutions at the room temperature. After drying specimen treated with chemicals, combustive properties were examined by the cone calorimeter (ISO 5660-1). As a result, the combustion-retardation properties were partially increased by due to the treated $PIPEABPM^{n+}$ solutions in the virgin Pinus rigida. Especially, the specimens treated with $PIPEABPM^{n+}$ showed both the lower peak heat release rate ($HRR_{peak}$) (173.48~145.36) s and total heat release rate (THRR) (73.0~55.2) $MJ/m^2$ than those of virgin piperazinomethyl-bis-phosphonic acid (PIPEABP)-plate. Compared with virgin PIPEABP-plate, the specimens treated with the $PIPEABPM^{n+}$ showed low combustive properties. However the specimens treated with $PIPEABPM^{n+}$ showed both the shorter time to ignition (TTI) (58~18) s and the time to flameout (Tf) (564~456) s than those of virgin PIPEABP-plate by increasing the thermal conductivity.

• Fire Science and Engineering
• /
• v.29 no.6
• /
• pp.13-19
• /
• 2015

This study was performed to test the combustive properties of Pinus rigida specimens treated with phosphorus (P) and nitrogen (N) additives. Each Pinus rigida specimen was painted three times with 15 wt% P-N additive solutions at room temperature. After drying the treated specimens, the combustion properties were examined using a cone calorimeter (ISO 5660-1). The time to ignition (TTI) for the treated specimens was 90 to 148 s except for the specimen treated with PP/$4NH_4^+$, and the time to flameout (TF) was 556 to 633 s, which was longer than that of virgin plate. While the The specimens treated with P-N additives showed 12.5 to 43.4% higher mean heat release rate ($HRR_{mean}$) and 11.8 to 43.1% higher total heat release (THR) than virgin plate. The effective heat of combustion (EHC) was by 2.9 to 17.5% lower than that of virgin plate. It can thus be concluded that the combustion-retardation properties were partially improved compared to those of virgin plate.

• Applied Chemistry for Engineering
• /
• v.25 no.5
• /
• pp.481-486
• /
• 2014

This study was performed to test combustive properties of medium density fibreboard (MDF) plates treated with piperazinomethyl-bis-phosphonic acid (PIPEABP), methylpiperazinomethyl-bis-phosphonic acid (MPIPEABP), and N,N-dimethylethylenediaminomethyl-bis-phosphonic acid (MDEDAP). MDF specimens were painted three times with 15 wt% solution of the alkylenediaminoalkyl-bis-phosphonic acids at room temperature. After drying specimen treated with chemicals, combustive properties were examined using the cone calorimeter (ISO 5660-1). As a result, combustion-retardation properties increased due to the treatment of bare MDF with alkylenediaminoalkyl-bis-phosphonic acid solution. Especially, the specimens treated with chemicals showed the ignition (TTI) (148 s~116 s) was retarded and the flameout (Tf) (633 s~529 s) time increased, while the total heat release rate (THRR) (61.1~67.0) $MJ/m^2$ was lowered than those of using virgin plate by reducing the burnig rate. Compared with virgin MDF plate, the specimens treated with the alkylenediaminoalkyl-bis-phosphonic acids showed low combustive properties. However the specimens treated with bis-(dimethylaminomethyl) phosphinic acid (DMDP) showed the higher peak heat release rate (PHRR) ($185.08kW/m^2$) than that of the virgin plate.

• Fire Science and Engineering
• /
• v.27 no.6
• /
• pp.70-76
• /
• 2013

Four kinds of new piperazinomethyl-bis-phosphonic acid $M^{n+}$ ($PIPEABPM^{n+}$) were synthesized and their combustive properties of Pinus rigida plates treated with $PIPEABPM^{n+}$ were tested. Pinus rigida specimens were painted in three times with 15 wt% $PIPEABPM^{n+}$solutions at the room temperature. After drying specimen treated with chemicals, com-bustive properties were examined by the cone calorimeter (ISO 5660-1). As a result, the combustion-retardation proper-ties were increased by due to the treated $PIPEABPM^{n+}$ solutions in the virgin pinus rigida. Especially, the specimens treated with $PIPEABPM^{n+}$ showed both the lower peak heat release rate ($HRR_{peak}$) (162.02~145.36) s and total heat release rate (THRR) (73.0~67.4) $MJ/m^2$ than those of virgin piperazinomethyl-bis-phosphonic acid (PIPEABP)-plate. Compared with virgin PIPEABP-plate, the specimens treated with the $PIPEABPM^{n+}$ showed low combustive properties. However the specimens treated with $PIPEABPM^{n+}$ showed both the shorter time to ignition (TTI) (67~23) s and the time to flameout (Tf) (472~433) s than those of virgin PIPEABP-plate by increasing the thermal conductivity.

• Fire Science and Engineering
• /
• v.27 no.5
• /
• pp.57-63
• /
• 2013

This study was performed to test the combustive properties of Pinus rigida plates treated with piperazinomethyl-bisphosphonic acid (PIPEABP), methylpiperazinomethyl-bis-phosphonic acid (MPIPEABP), and N,N-dimethylethylenediaminomethyl- bis-phosphonic acid (MDEDAP). Pinus rigida specimens were painted in three times with 15 wt% alkylenediaminoalkyl- bis-phosphonic acid solutions at the room temperature. After drying specimen treated with chemicals, combustive properties were examined by the cone calorimeter (ISO 5660-1). As a result, the combustion-retardation properties were increased by due to the treated alkylenediaminoalkyl-bis-phosphonic acid solutios in the virgin Pinus rigida. Especially, the specimens treated with chemicals showed both the later time to ignition (TTI) (148-116 s) and longer time to flameout (Tf) (633-529 s) than those of virgin plate by reducing the burnig rate. Compared with virgin pinus rigida plate, the specimens treated with the alkylenediaminoalkyl-bis-phosphonic acids showed partially low combustive properties. However the specimens treated with PIPEABP showed both the higher peak heat release rate (PHRR) (187.56 $kW/m^2$) and higher total heat release rate (THRR) (75.7 $MJ/m^2$) than those of virgin plate.