Cylindrical internal surface with thermally spray coating

Abstract

Before a thermally sprayed coating is deposited onto a cylindrical internal surface of a cylinder bore 3a rough surface 13 is formed to increase the adhesion of the thermally sprayed coating. After forming the rough surface is completed, an internal diameter measurement surface that is smoother than the rough surface is formed on an axial end section of the internal cylindrical surface. The internal diameter of the cylinder bore is measured at the internal diameter measurement surface with an internal diameter measuring instrument. An appropriate thickness for the thermally sprayed coating is determined based on the measurement result.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of this original disclosure:

FIG. 1 is a transverse cross sectional view of a cylinder block having a cylinder bore (internal cylindrical bore) with a thermally sprayed coating formed on its cylindrical internal surface in accordance with a first embodiment of the present invention;

FIG. 2 is an enlarged cross sectional view of an end portion of the cylinder block shown in FIG. 1 that is closer to a crankcase;

FIG. 3 is a series of cross sectional views of a portion of the cylindrical internal surface illustrating the processing applied to the cylinder bore of the cylinder block shown in FIG. 1;

FIG. 4 is a flowchart presenting the processing steps applied to the internal cylindrical bore of the cylinder block shown in FIG. 1;

FIG. 5 is a cross sectional view of the cylinder block in which a roughening process is being applied to the cylindrical internal surface of the base material of the cylinder block shown in FIG. 1;

FIG. 6A is an enlarged cross sectional view of a portion of the cylindrical internal surface illustrating how the base material surface roughening process shown in FIG. 4 is executed using a tool and the discharged cut waste material;

FIG. 6B is an enlarged cross sectional view of a portion of the cylindrical internal surface illustrating a typical screw thread cutting process executed using a tool;

FIG. 7 is a block diagram of a control configuration that compares a measured internal diameter to a threshold value in order to determine if the internal diameter is acceptable (i.e., good or bad);

FIG. 8 is a schematic view of an entire thermal spraying apparatus for depositing a thermally sprayed coating onto the internal surface of the cylinder bore of the cylinder block shown in FIG. 1 after the cylinder bore internal surface has been roughened;

FIG. 9 is a cross sectional view of the cylinder block shown in FIG. 1 illustrating the thermally sprayed coating being honed with a honing tool; and

FIG. 10 is a work flow diagram illustrating the flow of processing steps from the base material surface roughening shown in diagram (c) of FIG. 3 to the finishing (honing) shown in diagram (f) of FIG. 3.

Claims

1. A base member comprising: an internal cylindrical bore including a rough surface section and an internal diameter measurement surface section provided on an axial end of the internal cylindrical bore, the internal diameter measurement surface section being smoother than the rough surface section; anda thermally sprayed coating formed on the rough surface section of the internal cylindrical bore.

2. The base member as recited in claim 1, wherein the internal diameter measurement surface section is processed using a tool that is used to form the rough surface section.

3. The base member as recited in claim 2, wherein the rough surface section and the internal diameter measuring surface section are formed by cutting with the tool while the tool is both rotated and moved axially with an axial feed speed of the tool being slower when processing the internal diameter measurement surface section than when processing the rough surface section.

4. The base member as recited in claim 1, wherein the internal diameter measurement surface section has an internal diameter that is identical to a maximum internal diameter of the rough surface section as defined by a bottom of a recess of the rough surface section.

5. A cylindrical internal surface processing method comprising: providing a base member having an internal cylindrical bore;forming a rough surface section along an internal surface of the internal cylindrical bore;forming an internal diameter measurement surface section on an axial end of the internal cylindrical bore, with the internal diameter measurement surface section being smoother than the rough surface section; andforming a thermally sprayed coating onto the rough surface section of the internal surface of the internal cylindrical bore after forming the internal diameter measurement surface section.

6. The cylindrical internal surface processing method as recited in claim 5, wherein the forming of the internal diameter measurement surface section is performed using a tool that is used in the forming of the rough surface section of the internal cylindrical bore.

7. The cylindrical internal surface processing method as recited in claim 6, wherein: the forming of the rough surface section and the forming of the internal diameter measuring surface section are performed by cutting with the tool while both rotating and moved axially moving the tool, with an axial feed speed of the tool being slower when processing the internal diameter measurement surface section than when processing the rough surface section.

8. The cylindrical internal surface processing method as recited in claim 5, wherein the forming of the internal diameter measurement surface section is performed such that an internal diameter of the internal cylindrical bore at the internal diameter measurement surface section is made identical to a maximum internal diameter of the rough surface section as defined by a bottom of a recess of the rough surface section.

9. The cylindrical internal surface processing method as recited in claim 5, further comprising measuring an internal diameter of the internal diameter measurement surface section to obtain a measurement result of the internal diameter of the internal diameter measurement surface section; anddetermining an acceptability of the measurement result of the internal diameter of the internal diameter measurement surface section, and then performing the forming of the thermally sprayed coating onto the rough surface section of the internal surface of the internal cylindrical bore only if the measurement result is determined to be acceptable.

10. The cylindrical internal surface processing method as recited in claim 9, wherein the determining of the acceptability of the measurement result of the internal diameter of the internal diameter measurement surface section is based on a prescribed threshold value.

11. The cylindrical internal surface processing method as recited in claim 9, wherein the determining of the acceptability of the measurement result of the internal diameter of the internal diameter measurement surface section is determined to be acceptable when an internal diameter measurement value of the measurement result is equal to or smaller than a first prescribed threshold value and larger than a second prescribed threshold value such that a honing process can be performed entirely on the thermally sprayed coating along the rough surface section without at least a portion of the base member being exposed by the honing process of the thermally sprayed coating after the thermally sprayed coating is formed.

12. The cylindrical internal surface processing method as recited in claim 5, further comprising measuring an internal diameter of the internal diameter measurement surface section to obtain a measurement result of the internal diameter of the internal diameter measurement surface section; andadjusting a spray condition used in performing the forming of the thermally sprayed coating onto the rough surface section based on the measurement result of the internal diameter of the internal diameter measurement surface section.

13. The cylindrical internal surface processing method as recited in claim 12, wherein the forming of the thermally sprayed coating onto the rough surface section is performed by using a thermal spray gun configured to spray a molten coating material with the thermal spray gun moving reciprocally inside the internal cylindrical bore while rotating the thermal spray gun; andthe spray condition to be adjusted includes a number of times the thermal spray gun is moved reciprocally inside the internal cylindrical bore.

14. The cylindrical internal surface processing method as recited in claim 13, wherein the adjusting of the spray condition includes increasing the number of times the thermal spray gun is moved reciprocally as the measurement result of the internal diameter of the internal diameter measurement surface section becomes larger.

15. The cylindrical internal surface processing method as recited in claim 9, further comprising removing the internal diameter measurement surface section together with the thermally sprayed coating in a vicinity of the internal diameter measurement surface section after the thermally sprayed coating is formed.

16. A cylindrical internal surface processing apparatus comprising: an internal diameter measuring device configured to measure an internal diameter of an internal cylindrical bore formed in a base member to obtain a measurement result of the internal diameter; anda quality determining section configured to determine if the internal diameter measurement result obtained by the internal diameter measuring device is acceptable to allow a subsequent thermally sprayed coating to be applied.

17. The cylindrical internal surface processing apparatus as recited in claim 16, wherein the quality determining section is further configured to determine an acceptability of the measurement result of the internal diameter measurement surface section is based on a prescribed threshold value.

18. The cylindrical internal surface processing apparatus recited in claim 17, wherein the quality determining section is configured to determine that the measurement result of the internal diameter measurement is acceptable when an internal diameter measurement value is equal to or smaller than a first prescribed threshold value and larger than a second prescribed threshold value such that a honing process can be performed entirely on the thermally sprayed coating along the rough surface section without at least a portion of the base member being exposed by the honing process of the thermally sprayed coating after the thermally sprayed coating is formed.