Cylinder liner, cylinder block and process for the preparation of cylinder liner

A cast iron cylinder liner having a shape of cylinder hollow to be enclosed in a cylinder block main body made of aluminum alloy by enclosing-casting method, which comprises a strip-shaped plane surface spirally extending in a circumferential direction of the cylinder liner, the spiral strip-shaped plane surface being formed on an outer circumferential surface of the cylinder liner at intervals in the axis direction, and a circumferential groove spirally and continuously formed between the spiral strip-shaped plane surface,

• the circumferential groove of the cylinder liner in an axial sectional view comprising:
• a first circumferential groove comprising,
• a first slant surface whose diameter is gradually reduced with moving from an outer circumferential edge of a strip-shaped plane surface existing in one end side in an axial direction of the cylinder liner to the one end side in the axial direction of the cylinder liner to undercut a support portion of the strip-shaped plane surface,
• a first curved surface whose diameter is gradually reduced with moving from an inner circumferential end of the first slant surface, and
• a second slant surface whose diameter is gradually increased with moving from an inner circumferential end of the first curved surface to the other end side in the axial direction of the cylinder liner and which faces the first slant surface,
• the first slant surface, the first curved surface and the second slant surface being continuously linked to each other in this order to form a shape of “J” of the alphabet in section view;
• and
• a second circumferential groove comprising,
• a third slant surface which continuously links to an outer circumferential end of the second slant surface and whose diameter is gradually reduced with moving to the other end side in the axial direction of the cylinder liner,
• a second curved surface whose diameter is gradually increased with moving from an inner circumferential end of the third slant surface, and
• a forth slant surface whose diameter is increased with moving from an outer circumferential end of the second curved surface to the one end side in the axial direction of the cylinder liner, which faces the third slant surface and whose outer circumferential end links to an outer circumferential edge of an adjacent strip-shaped plane surface existing in the other end side in an axial direction of the cylinder liner to undercut a support portion of the strip-shaped plane surface,
• the third slant surface, the second curved surface and the forth slant surface being continuously linked to each other in this order to form a shape of “J” of the alphabet in section view.

A process for the preparation of a cast iron cylinder liner having a shape of cylinder hollow to be enclosed in a cylinder block main body made of aluminum alloy by enclosing-casting method, which comprises a plurality of strip-shaped plane surfaces circularly extending in a circumferential direction of the cylinder liner, the circular strip-shaped plane surfaces being formed on an outer circumferential surface of the cylinder liner at intervals in the axis direction, and a plurality of circumferential grooves extending in the circumferential direction, the circumferential grooves being formed between the adjacent strip-shaped plane surfaces, comprising the following steps:

• rotating a cylinder liner material casted in the form of circular cylinder around its central axis, and applying a working tool onto an outer circumferential surface of the material to cut a plurality of first circumferential grooves in the axial direction at intervals,
• each of the first circumferential grooves comprising,
• a first slant surface which, in its axial sectional view, has circular shape and whose diameter is gradually reduced with moving from an outer circumferential edge of a strip-shaped plane surface existing in one end side in an axial direction of the cylinder liner to the one end side in the axial direction of the cylinder liner to undercut a support portion of the strip-shaped plane surface,
• a first curved surface whose, in its axial sectional view, diameter is gradually reduced with moving from an inner circumferential end of the first slant surface, and
• a second slant surface whose, in its axial sectional view, diameter is gradually increased with moving from an inner circumferential end of the first curved surface to the other end side in the axial direction of the cylinder liner and which faces the first slant surface,
• the first slant surface, the first curved surface and the second slant surface being continuously linked to each other in this order to form a shape of “J” of the alphabet in sectional view;
• and
• rotating the cylinder liner material, on which the plurality of first circumferential grooves have been provided by the cutting, around its central axis, and applying a working tool onto the material to cut a plurality of second circumferential grooves in the axis direction at intervals,
• each of the second circumferential grooves comprising,
• a third slant surface which, in its axial sectional view, continuously links to an outer circumferential end of the second slant surface and whose diameter is gradually reduced with moving to the other end side in the axial direction of the cylinder liner,
• a second curved surface whose, in its axial sectional view, diameter is gradually increased with moving from an inner circumferential end of the third slant surface, and
• a forth slant surface whose, in its axial sectional view, diameter is increased with moving from an outer circumferential end of the second curved surface to the one end side in the axial direction of the cylinder liner, which faces the third slant surface and whose outer circumferential end links to an outer circumferential edge of an adjacent strip-shaped plane surface existing in the other end side in an axial direction of the cylinder liner to undercut a support portion of the strip-shaped plane surface,
• the third slant surface, the second curved surface and the forth slant surface being continuously linked to each other in this order to form a shape of “J” of the alphabet in sectional view.

A process for the preparation of a cast iron cylinder liner having a shape of cylinder hollow to be enclosed in a cylinder block main body made of aluminum alloy by enclosing-casting method, which comprises a strip-shaped plane surface spirally extending in a circumferential direction of the cylinder liner, the spiral strip-shaped plane surface being formed on an outer circumferential surface of the cylinder liner at intervals in the axis direction, and a circumferential groove spirally and continuously formed between the spiral strip-shaped plane surface, comprising the following steps:

• rotating a cylinder liner material casted in the form of circular cylinder around its central axis, and applying a working tool onto an outer circumferential surface of the material with moving the tool from one end side in an axis direction of the cylinder liner to the other side end in parallel to the central axis, to cut a first circumferential groove,
• the first circumferential groove comprising,
• a spiral first slant surface whose, in its axial sectional view, diameter is gradually reduced with moving from an outer circumferential edge of a strip-shaped plane surface existing in the one end side in an axial direction of the cylinder liner to the one end side in the axial direction of the cylinder liner to undercut a support portion of the strip-shaped plane surface,
• a first curved surface whose, in its axial sectional view, diameter is gradually reduced with moving from an inner circumferential end of the first slant surface, and
• a second slant surface whose, in its axial sectional view, diameter is gradually increased with moving from an inner circumferential end of the first curved surface to the other end side in the axial direction of the cylinder liner and which faces the first slant surface,
• the first slant surface, the first curved surface and the second slant surface being continuously linked to each other in this order to form a shape of “J” of the alphabet in sectional view;
• and
• rotating the cylinder liner material, on which the spiral first circumferential groove has been provided by the cutting, around its central axis in a direction opposite to the above-mentioned rotating direction, and applying a working tool onto an outer circumferential surface of the material with moving the tool from the other end side in an axis direction of the cylinder liner to the one side end and in parallel to the central axis, to cut a second circumferential groove,
• the second circumferential groove comprising,
• a spiral third slant surface which, in its axial sectional view, continuously links to an outer circumferential end of the second slant surface and whose diameter is gradually reduced with moving to the other end side in the axial direction of the cylinder liner,
• a second curved surface, in its axial sectional view, whose diameter is gradually increased with moving from an inner circumferential end of the third slant surface, and
• a forth slant surface, in its axial sectional view, whose diameter is increased with moving from an outer circumferential end of the second curved surface to the one end side in the axial direction of the cylinder liner, which faces the third slant surface and whose outer circumferential end links to an outer circumferential edge of an adjacent strip-shaped plane surface existing in the other end side in an axial direction of the cylinder liner to undercut a support portion of the strip-shaped plane surface,
• the third slant surface, the second curved surface and the forth slant surface being continuously linked to each other in this order to form a shape of “J” of the alphabet in sectional view.