Reaming - Course: Techniques for Machining of Material. Instruction Examples for Practical Vocational Training: Instruction example 6.4.: Drilling block

Reaming - Course: Techniques for Machining of Material. Instruction Examples for Practical Vocational Training

		(introduction...)
		Introduction
		Instruction example 6.1.: Bush
		Instruction example 6.2.: Indexing bearing
		Instruction example 6.3.: Flange
		Instruction example 6.4.: Drilling block

This example serves to practise reaming of taper through holes in prismatic and rotationally symmetrical parts.

Figure

Material

St 60 = 2 (St = steel, 60 = 600 MPa tensile strength, 2 = grade)

Dimensions

dia. 50 x 107 mm

Cutting tools

Centre drill A 2.5; twist drill dia. 24; boring tool for corner work; taper reamer M.T. 4

Measuring and testing tools

Vernier caliper, taper plug gauge M.T. 4

Accessories

Taper sleeves, drill chuck, four-jaw chuck, coolant and lubricant, try-out paste or chalk

Required previous knowledge

Reading of drawings; measuring and testing; centring; drilling and counterboring/countersinking; manual reaming

Explanations to the working drawing

Sequence of operations		Remarks

1.	Measuring of blank	Separate undersize parts (length).

2.	Clamping of workpiece	Type of clamping: “chucking” in a four-jaw chuck using hard chuck jaws.

3.	Centring	Ensure central position. In case of offset align chuck and/or tailstock sleeve.

4.	Drilling	Use coolant. Produce through hole.

5.	Boring of hole	Swivel top slide by a/2 = 1°29’15’’. Take test cut, adjust in case of deviations (several times until taper is bearing over entire length of workpiece), turn by hand, pay attention to machining allowance (for 0.30 mm allowance on dia. - 5.78 mm pre-fitting length). Check for dimensions and surface finish.

6.	Reaming	Use coolant. Finish reaming constantly checking the size. Observe surface pattern. Guide reamer equally.

7.	Unloading of workpiece

8.	Dimensional and surface finish inspection	The workpiece is to be de-burred at both ends. For pre-inspection and final inspection of taper bearing capacity use adequate means (try-out paste or chalk).

Figure