4. Shaping of surfaces standing at an angle to each other and stepped surfaces

For machining of surfaces standing at an angle to each other the same manufacturing techniques as for shaping of plane surfaces and end faces, inclined and parallel surfaces can be applied. The workpieces shall be clamped in such a manner that the surfaces to be machined are accessible from the operating side of the machine, if possible. As a rule, the surfaces inclined to each other are shaped separately. If surfaces meeting under an acute angle are approximately 15 to 20 mm wide, the angle section can be cut out also from the solid material. The surfaces are at first roughed, then finished.

The choice of corresponding shaper tools depends on the angle under which the surfaces to be machined meet. Surfaces standing at an angle to each other should be machined in one clamping if possible, in order to avoid steps that may arise due to changes of the position during relocating.

The tool shall be adjusted according to the angle required. Surfaces standing at an angle to each other are roughed at first in the direction of the inclined surface from the top downwards, then horizontally from the outside inwards.

Finishing is made, as a rule, with pointed side-cutting planer tools which according to the angle of inclination of the surfaces to be machined are ground on both sides.

The angle and its position shall be checked after roughing so that a correction is possible during finishing. The angle shall be checked at both ends and in the middle of the workpiece. When workpieces sensitive to distortion are machined, they should be unloaded (released and tightened again) before finishing to avoid distortions.

Shaping of stepped surfaces can also be understood as shaping of profiles or shaping with formed tool. This concerns workpieces which are composed of various surfaces and shapes. Being horizontal, vertical, parallel, inclined and angular surfaces, they form different geometrical shapes.

Figure 26. Contour

Such surfaces are often shaped, as they can be manufactured with relatively simple tools at lower costs than with milling tools.

Simple stepped surfaces (see Fig. 3) can be produced, as a rule, with the usual shaping tools.

A distinction should be made between shaping of plane surfaces and end faces.

In doing so, the position of the tool depends on the required surface contour of the workpiece. At any rate it must be possible for the tool to cut freely and to be returned.

The exact position of the workpiece in the case of shaping plane surfaces (horizontal surface) is reached by:

- putting and clamping that side on the machine table which has been machined first (make sure that the bearing surfaces are clean and even);

- underlaying of strips ground parallel in the machine vice.

The exact position of the workpiece in the case of shaping end faces (vertical surfaces) is reached by:

- putting and clamping the side machined first against stops and tongues;

- alignment of a vertical reference surface already machined by checking with the dial gauge in longitudinal direction.

In doing so, make sure that the dial gauge tip follows the ram path (use a special holder, if necessary).

- alignment of the machine vice in longitudinal or transverse direction

Figure 27. Checking of the workpiece position at a reference surface (1 vice, 2 workpiece, 3 tool slide with clamped dial gauge, 4 direction of movement, 5 reference surface)

Simple stepped surfaces should always be finish-shaped from the maximum size to the minium size.

Shaping of stepped surfaces possessing a physical shape or profile is characterized by having the shape or the profile of the required workpiece surface machined in the tool (forming tool) or by adjusting the tool at an angle to the workpiece. Stepped shapes or profiles are made mostly in the last working step. The surfaces and edges already machined serve as reference surfaces.

At which points of the workpiece are angles to be checked?
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How is an exact position of the workpiece reached when vertical surfaces are slotted?
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What are the main working steps of machining by shaping?

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