tailieunhanh - Handbook of Shaft Alignment Part 11

Tham khảo tài liệu 'handbook of shaft alignment part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 16 Measuring and Compensating for Off-Line to Running Machinery Movement Up to this point in the book we discussed how to align rotating machinery when it is shut down and hopefully in a very stable position. Once the shafts are aligned within acceptable tolerances the coupling engaged and the machinery started up changes in the positions of the shafts may begin to occur that could alter the accuracy of the alignment when the equipment is running. Virtually all rotating equipments will undergo a change in position during start-up and while running that affects the alignment of the shafts. The driver machine may move a certain amount and in a certain direction as it goes from an off-line to a stable operating condition. The driven elements of the system may move different amounts and in different directions. In order for the shafts to run collinear under normal operating conditions it is desirable to know the amount and direction of this movement to properly position the machinery during what is commonly called the cold . off-line or not running alignment process to compensate for this change. WHAT TYPE OF MACHINERY IS LIKELY TO CHANGE EQUIPMENT S POSITION WHEN RUNNING The OL2R movement characteristics of the vast majority of rotating machinery drive systems in existence have never been measured. Based on observations made on a relatively small percentage of drive systems currently operating it appears that perhaps on 60 -70 of the drive systems in existence the amount of movement is negligible and can basically be ignored. In the remaining cases however this movement can make all the difference between a troublefree drive system and one that is plagued with problems. It is important to know how much movement is occurring before you deem it insignificant and ignore it. The most baffling question is which rotating machinery do you have that is moving enough from OL2R conditions where you need to measure and compensate for this movement. Below is a broad list