| Abstract [eng] |
In this Master degree work there is a description of a safety clutch of a perforator with SDS + chuck. Perforrator‘s main purpose is to drill holes in concrete, metal and wood. Safety clutch purpose is to ensure safety of electrical engine from overworking, which occurs in drilling with drill bit or crown. Safety clutch starts working when electrical engines spins pinion which is placed on cylinder. Pinion is being presseed by the spring to the cylinder‘s knuckles. Drill bit is being placed in the cylinder and when drill bit stucks or if there‘s too high resistance, knuckle goes up and overcomes spings tensile strength – pinion‘s and cylinders knuckles excel. When safety clutch starts working, pinions slide at each other and as friction exists safety clutch‘s pinions worn out. Changing worned out pinions is not complicated, but price of repair takes up to 50 % of a new perforator price. In this Master Degree work there is a comparison of four similar types of perforator safety clutches. Parameters which are included in the comparison is maximum drilling diameter in concrete, perforator price, clutch elements and safety clutch elements repair price. According to these parameters, manufacturer‘s no.4 clutch is decided to be the weakest link. Also there is stated clutch‘s stiffness coefficient – 333. According to the stiffness coefficient, spring pushes pinion with a force of 667 N or 6,67 kg. Averange torque is also stated in this work, as it is needed to make safety clutch work – 73 Nm. In the researched safety clutch knuckles are changed by rolls – rolls can be repaired independently from other safety clutch‘s elements. Maximum torque is set which is needed to start the modernized clutch work. The max torque is 78 Nm. |
