• 한국기계가공학회지
• /
• 제19권11호
• /
• pp.64-69
• /
• 2020

To determine the effective factors for microparticle blasting with precise sequence position control in the x-axis and y-axis directions, we conducted a statistical experimental analysis of blasted square shapes by considering five condition factors. The control input and output were operated simultaneously by rotation-linear motion conversion and fine particles were blasted onto the aluminum specimen by precise position control driving using multiple execution codes. The micro-driving device used for processing was capable of microparticle blasting and of controlling the system through contact with a limit sensor at high speed and a two-degree-of-freedom driving mechanism. Our experiments were conducted on 1,050 specimens of pure aluminum (containing <1% of other elements). The effects of several factors (e.g., particle and nozzle diameters, blasting pressure, and federate and blasting cycle numbers) on the surface roughness and blasted surface's depth were verified through a statistical experimental analysis by applying the dispersion analysis method. This statistical analysis revealed that the nozzle diameter, the blasting pressure, and the blasting cycle number were the dominant factors.

• 화약ㆍ발파
• /
• 제13권1호
• /
• pp.20-31
• /
• 1995

Many methods and techniques to reduce ground vibrations are well known. Some of them are to adopt electric milisecond detonators with a sequential blasting machine or an initiating system with an adequate number of delay intervals. The types of electric detonators munufactured in Korea include instantaneous, decisecond and milisecond delays byt numbers of delay intervals are only limite from No.1 to No.20 respectively. It is not sufficient to control accurately milisecond time with these detonators in tunnel excavation. Sequential fire time refers to adding an external time delay to a detonators norminal firing time to obtain sequential initiation and it is determined by sequential timer setting. To reduce the vibration level, sequential blasting machine with decisecond detonatore was adopted. A total of 134 blasting was recorded at various sites. Blast-to-structure distances ranged from 20.3 to 42.0 meter, where charge weight varied from 0.25 to 0.75 kg per delay. The results can be summarized as follow : 1. The effects of sequential blasting machine on the vibration level are discussed. The vibration level by S.B.M. are decreased approximately 14.38~18.05 to compare to level of conventional blasting and cycle time per round can be saved. 2. The empirical equations of particle velocity were obtained in S,B.M. and conventional blastin. $V=K(D/W^{1/3})-n$. where the values for n and k are estimated to be 1.665 to 1.710 and 93.59 to 137 respectively. 3. The growth of cracks due to vibrations are found but the level fall to within allowable value.

• 화약ㆍ발파
• /
• 제33권3호
• /
• pp.14-20
• /
• 2015

발파터널의 건설과정에 있어서 가장 중요한 역할을 차지하는 발파작업은 암질상태, 터널의 규모, 사용 장비의 성능, 작업자들의 숙련도 등 다양한 요인에 의해 작업시간에서 차이를 나타낸다. 본 논문에서는 국내 세 곳의 터널발파 현장에서의 발파작업시간 조사를 통해, 표준품셈에서 계산되는 터널발파 사이클 시간과 실제 시공시간과의 차이를 분석하였다. 그 결과, 정상적인 작업이 이루어진 경우 전체적으로 실제 발파작업시간은 품셈보다 약 8%~ 16% 적게 나타나고 있다. 그러나 예상치 못한 상황으로 인해 지연되는 시간까지 포함한다면 실제 작업시간이 품셈을 초과하는 경우가 상당할 것으로 추정되었다. 본 연구는 향후에도 지속적인 작업시간 조사와 품셈과의 비교 분석을 통해 품셈의 적절성을 판단함과 아울러, 발파 굴착의 생산성을 향상시키는데 도움을 주고자 한다.

• 터널과지하공간
• /
• 제4권2호
• /
• pp.132-143
• /
• 1994

Many methods and techniques to reduce ground vibrations are well known. Some of them are to adopt electric millisecond detonators with a sequential blasting machine or an initiating system with an adequate number of delay intervals. The types of electric detonators manufactured in korea include instantaneous, decisecond and millisecond delays but numbers of delay intervals are only limited from No.1 to No.20 respectively. It is not sufficient to control accurately millisecond time with these detonators in tunnel excavation. Sequential fire time refers to adding an external time delay to a detonators norminal firing time to obtain sequential initiation and it is determined by sequential timer setting. To reduce the vibration level, sequential blasting machine(S.B.M) with decisecond detonators was adopted. A total of 134 blasts was recorede at various sites. Blast-to-structure distances ranged from 20.3 to 42.0 meter, where charge weight varied from 0.24 to 0.75 kg per delay. The results can be summarized as follow: 1. The effects of sequential blasting machine on the vibration level are discussed. The vibration level by S.B.M are decreased approximately 14.38~18.05% compare to level of conventional blasting and cycle time per round can be saved. 2. The empirical equations of particle velocity were obtained in S.B.M and conventional blasting. V=K(D/W1/3)-n, where the values for n and k are estimated to be 1.665 to 1.710 and 93.59 to 137 respectively. 3. The growth of cracks due to vibrations are found but the level fall to within allowable value.