Solved
Increasing every hours in each iteration using for loop in thingworx.
var date = new Date();
for (let index = 0; index < 12; index++) {
let startDate = new Date(date);
startDate.setHours(18 + index, 0, 0);
let endDate = new Date(date);
endDate.setHours(18 + index + 1, 0, 0);
console.log("StartDate " + startDate);
console.log("EndDate " + endDate);
}


