tailieunhanh - Drilling and Associated Technologies Part 6

Tham khảo tài liệu 'drilling and associated technologies part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Drilling and Associated Technologies 137 slice levels with helical wandering o Figure 70. The exaggerated hole errors caused by an incorrect drill point geometry and the manufacturing techniques for its subsequent correction 138 Chapter 3 Figure 71. Reaming can correct an assymetrically drilled hole - when correctly adjusted Drilling and Associated Technologies 139 large harmonic variation in the plots is depicted as is the case when a Floating reamer with roller drive has been used inappropriately. Floating Reaming Cylinder head tappet rail drill-reaming - in a single operation Cylinder head valve seats and guides - machining both features in the parent bore and finish machining Solid machine reamers can be floated-down 59 a predrilled hole to produce a much straighter reamed hole than would otherwise be the case. When floating reamers within their specially-located toolholders two techniques are used to float reamers see Fig. 72 these are 1. Radial play - where the machine reamer has limited movement laterally with respect to the principal axis 2. Composed radial and pendulum play - this has both radial play together with a degree of limited angular movement . this motion is similar to that of a Grandfather clock s timing mechanism via its pendulum motion . NB This latter floating technique has the potential for a combination of both radial and pendulum motions to the machine reamer. These unrestrained kinematic motions gives it free motion without lateral and angular constraint to simply follow the line of least resistance along the spindle axis as the reamer progressively feeds down through the predrilled workpiece. Radially-Adjustable Machine Reamers Special-purpose machine drill reamers Fig. 74a are often utilised in high-volume production environments such as in the automotive sector for utility engines which can account for 55 000 complexreaming operations per week. Conversely for defence vehicle engines the production volumes are quite low .