GB2525411A

GB2525411A - A method of material-spray coating an engine component

Info

Publication number: GB2525411A
Application number: GB1407191.4A
Authority: GB
Inventors: Christopher Smith
Original assignee: Caterpillar Shrewsbury Ltd
Current assignee: Caterpillar Shrewsbury Ltd
Priority date: 2014-04-24
Filing date: 2014-04-24
Publication date: 2015-10-28
Anticipated expiration: 2034-04-24
Also published as: GB2525411B; GB201407191D0

Abstract

A method is provided for material-spray coating an engine component 1 having a plurality of support portions 9-1, 9-2, 9-3, 9-4, 9-5, each support portion having an aperture therein, the support portions being arranged in a segregated manner along a central axis X so that the respective apertures of each support portion cooperate with one another to form a bore (5, figure 1) along the central axis, the support portions being provided for rotatably supporting another engine component. The method comprises: locating a blocking device (37, figures 3 and 4) between adjacent support portions so that a through-hole of the blocking device cooperates with the respective apertures of the adjacent support portions and so that an inner surface is provided by the adjacent support portions and the blocking device; and moving a material-spray device 49 substantially along the central axis and through the bore so as to allow at least a portion of the inner surface to be coated with material-spray. The blocking device (37, figures 3 and 4) may be flexible so that it is deformed before inserting between adjacent support portions. The engine component 1 is preferably a cylinder block, with the plurality of support portions 9-1, 9-2, 9-3, 9-4, 9-5 comprising bearing portions in which a crankshaft or camshaft is located. Preferably molten metal is sprayed onto the bearing surfaces.

Description

A method of material-spray coating an engine component

Technical field

The present disclosure relates to a method of material-spray coating an engine component. More particularly, the present disclosure relates to a method of material-spray coating an engine component having a plurality of support portions.

Background

Mi internal combustion engine is made up of many component parts, which interact together so as to allow operation of the engine. Such component parts may require repThcement or repair due to a number of reasons.

For example, a cylinder block crank bore can be damaged by a rotating crankshaft when there is a shortage of lubricant oil. In more detail, the cylinder block crank bore is formed from several segregated support portions, known as bearings, which are connected to one another and are provided to support the crankshaft. Bearing shells are provided within the bearings and the crankshaft may rotate within the bearing shells on a thin film of oil. The bearing shells may have small protrusions in the form of "tangs", which protrude into the bearings to help them properly locate in the bearings in a manner that they cannot easily change position. The tangs are formed by two parallel cuts at one of the bearing shell and then by bending the section there between so that it protrudes away from the rest of the body of the bearing shell.

When there is a shortage of oil, the bearing shells may overheat and stick to the crankshaft. This causes the bearing shells to spin with the rotating crankshaft. The spinning of the bearing shells within the bearings causes damage to the internal surfaces of the bearings. For example, the tangs on the spinning bearing shells may cause a gouging of material from the bearing surfaces.

Accordingly, due to the damage to the bearings sustained by the spinning bearing shells, the cylinder block will reguire replacing, which can be an expensive process.

Summary

According to one aspect of the present disclosure, there is provided a method of material-spray coating an engine component having a plurality of support portions, each support portion having an aperture therein, the support portions being arranged in a segregated manner along a central axis so that the respective apertures of each support portion cooperate with one another to form a bore along the central axis, the support portions being provided for rotatably supporting another engine component, the method comprising: locating a blocking device between adjacent support portions so that a through-hole of the blocking device cooperates with the respective apertures of the adjacent support portions and so that an inner surface is provided by the adjacent support portions and the blocking device; and moving a material-spray device substantially along the central axis and through the bore so as to allow at least a portion of the inner surface to be coated with material-spray.

Brief description of the drawings

Aspects of the present disclosure will now be described, by way of example only, with reference to the following figures, in which: Figure 1 is a perspective view cf a cylinder block; Figure 2 is an exploded view of a support portion of the cylinder block of Figure 1; Figure 3 is a perspective view of a blocking device according to an embodiment of the present disclosure; Figure 4 is a schematic showing the blocking device of Figure 3 being used with the cylinder block of Figure 1; and Figure 5 is a schematic showing a material-spray coating process being performed.

Detailed description

Embodiments of the present disclosure relate to a method material-spray coating an engine component. The nethod may be used, in some cases, for generally applying material-spray coatings to an engine component. :n other cases, the method may be used for repair of a damaged engine component. A blocking device is described herein, which can be placed between support portions, which define a segregated bore (e.g. in which a crankshaft can be located) so as to restrict surface areas of the segregated bore that can be coated with material during a material-spray process.

Whilst embodiments of the present disclosure have been described herein with reference to a cylinder block crank bore, it will be appreciated that the principles of the present disclosure will be applicable to any segregated structure having a bore therein. For example, the present disclosure may additionally or alternatively be applicable to a segregated bore used to support a camshaft (both for the case of a camshaft located in the cylinder block and in the case of an overhead camshaft located in a rocker box) Figure 1 is a perspective view of a cylinder block 1 of an internal combustion engine (not shown) , such as a diesel engine. The cylinder block 1 has a central axis X. The cylinder block 1 comprises a housing 3, which at least partially defines a primary bore 5 therein. The primary bore 5 is located along the central axis X. A secondary bore 7 is located adjacent to the primary bore 5 and is also at least partially defined by the housing 3 of the cylinder block 1. In this exemplary embodiment, the primary bore 5 is for locating a crankshaft (not shown) therein and the secondary bore 7 is for locating a camshaft (not shown) therein.

More particularly, the primary bore 5 is at least partially defined by a plurality of support portions 9 (shown in more detail in Figure 2) arranged in a segregated manner along the central axis X (i.e. spaced along the central axis at regular intervals) . Each support portion 9 comprises an aperture 10 or through-hole having a generally circular cross-section. The apertures 10 of each support portion 9 are aligned along the central axis X so as to at least partially define the primary bore 5. In this manner, the support portions 9 are configured to rotatabiy support an engine component such as a crankshaft.

Referring to Figure 2, each support portion 9 comprises a lower bearing portion 11 and an upper bearing portion 13, which are secured together using bolts 15. Tn this example, the lower bearing portion 11 is integrally formed with the housing 3 (see Figure 1) and the upper bearing portion 13 is separately formed from the housing 3. The upper bearing portion 13 is constructed and arranged to fit the lower bearing portion 11 via mating surfaces 17-1, 17-2, 19-1, 19- 2 of both the upper and lower bearing portions 11, 13. For example, the upper and lower bearing portions 11, 13 may initially be formed together and then subsequently divided by a outting operation.

The lower bearing portion 11 comprises a lower radial inner surface 21 and the upper bearing portion 13 comprises an upper radial inner surface 23, such that the aperture 10 is defined by the lower and upper radial inner surfaces 21, 23 when the lower bearing portion 11 and the upper bearing portion 13 are brought together.

Lower bearing shells 25 and upper bearing shells 27, sometimes called "half-bearing shells", are respectively provided on the lower and upper inner radial surfaces 21, 23 of the respective lower and upper bearing portions 11, 13.

A protrusion 29, also known as a "tang" is provided on an outer surface of the lower bearing shell 25, which communicates with a location slot 31 of the lower bearing portion U. The protrusion 29 assists location of the lower bearing shell 25 on the lower bearing portion 11 and helps retain the lower bearing shell 25 in position on the lower bearing portion 11.

Similarly, a protrusion 33 is provided on an outer surface of the upper bearing shell 27 and can communicate with a location slot 35 of the upper bearing portion 13.

Figure 3 is a perspective view of a blocking device 37 in accordance with an embodiment of the present disclosure.

The blocking device 37, in this example, takes the form of a tube, and more particularly, a hollow cylindrical tube having a first end 39, a second end 41 and a peripheral side wall 43 extending between the first end 39 and the second end 41. A through-hole 45 is provided between the first end 39 and the second end 41. The through-hole 45 is sized and shaped with dimensions so as to allow a material-spray device (described herein with reference to Figure 5) to pass within the through-hole 45 from the first end 39 to the second end 41. In this exemplary embodiment, the through-hole has a constant radius defined by an inner surface 46 of the blocking device 37. The constant radius is substantially the same as the radius of the primary bore S as defined by the apertures 10 of the support portions 9.

The peripheral side wall 43 comprises a length substantially egual or greater than a distance between adjacent support portions 9.

The blocking device 37 comprises a material that is resilient and flexible, such that it can temporarily deform under force but can return to its original shape when such a force is removed. For example, the blocking device 37 may comprise a polymer or elastomer such as silicon or rubber.

A method of material-spray coating the inner surfaces of the support portions 9 will now be described with reference to Figures 4 and 5. In particular, the described method is for repairing damaged surfaces of the support portions 9.

Figure 4 is a simplified cross-sectional view of the segmented arrangement of the support portions 9 defining the primary bore 5. In this arrangement, the lower bearing shells 25 and the upper bearing shells 27 have been removed from selected lower bearing portions 11 and the upper bearing portions 13. This is done by first removing the bolts 15-1, 15-2, then removing the upper bearing portions 13, removing the bearing shells 25, 27 and then re-attaching the upper bearing portions 13 to their respective lower bearing portions 11. The lower radial inner surfaces 21 and the upper radial inner surfaces 23 have then been machined" using specialist tools to remove layers of material from these surfaces. This is to ensure that the aperture 10 defined by these lower and upper radial inner surfaces 21, 23 has a constant radius so that a subsequent material-spray operation may build up layers of material on the relevant support portions 9 in an even manner. In some exemplary embodiments, only selected support portions 9 are machined in this manner, however in other exemplary embodinents, all of the support portions 9 are machined in this manner.

In a first step, the blocking device 37 is temporarily deformed in an axial direction (i.e. along the direction of the through-hole 45) under a force.

Next, the blocking device 37, whilst being temporarily deformed, is placed between a selected pair of adjacent support portions 9. In this example, a single blocking device 37 has been placed between a first support portion 9-1 and a second support portion 9-2. The blocking device 37 is arranged so that the through-hole 45 aligns with the central axis X and the apertures 10 of the suppcrt portions 9-1, 9-2.

The force cn the blocking device 37 is then removed, thus allowing the blocking device 37 to axially expand to its original, non-deformed state. As the blocking device 37 is dimensioned with a length greater than the separation distance between the adjacent support portions 9-1, 9-2, the blocking device 37 cannot return to its original, non-deformed state but instead exerts a force against the support portions 9-1, 9-2. More particularly, the first end 39 of the blocking device 37 pushes against the first support portion 9-1 and the second end 41 of the blocking device 37 pushes against the second support portion 9-2.

The material composition of the blocking device 37 allows the first end 39 and the second end 41 to conform to the surfaces of the support portions 9-1, 9-2 with which they are in contact. In this manner, the inner surface 46 of the blocking device 46 is continuous with the lower inner radial surfaces 21 and upper inner radial surfaces 23 of the respective first and second support portions 9-1, 9-2 (i.e. there are no significant gaps between the adjacent support portions 9-1, 9-2 and the blocking device 37) Next, as shown in Figure 5, a material-spray device 49 is introduced to the primary bore 5. The material-spray device may, for example, comprise a spray head 51 rotatably mounted on a rod 53. The spray head 51 may comprise a nozzle 55 and may be configured to spray material out of the nozzle 55, whilst rotating about the rod 53. The material-spray device 49 may therefore be introduced to the primary bore 5 along the central axis X and may begin a selective material-spray operation once inside the primary bore 5. The spray head 51 may rotate about the rod and about the central axis X as the material spray device 49 travels along the primary bore 5 along the central axis X in the direction depicted by arrow 57. The continuous inner surface provided by the blocking device may therefore be coated with the material-spray from the material-spray device 49. The blocking device 37 acts to prevent material-spray from reaching surfaces other than those belonging to the first and second support portions 9-1, 9-2.

It will be appreciated that one or more blocking devices 37 may be provided between pairs of adjacent support portions 9, as required. For example, in situations where only a single support portion 9 requires material-spray coating, a single blocking device 37 can be used or two blocking devices 37 may be used either side of the designated support portion 9. Thereafter, the material-spray device 49 may be actuated only when it is determined that it is in the vicinity of the designated support portion 9 within the primary bore 5. In other examples, a blocking device 37 is provided between every gap in the segregated bore. In this manner, the gaps are sealed. The material-spray process can then be continuous as the material-spray device 49 travels along the primary bore 5.

Once the material-spray process is complete, the one or more blocking devices 37 can then be removed. Any material collected within the blocking devices 37 can be removed so that the blocking devices 37 may be removed.

Following removal of the one or more blocking devices 37, a second machining process (i.e. removal of material from the lower and upper inner radial surfaces 21, 23) may take place so as to ensure that the apertures 10 will be the appropriate size for the respective support portions 9 to perform their function (e.g. to rotatably support a crankshaft) . New location slots 31, 35 may reguire forming so as to allow location of lower and upper bearing shells 25, 27 in their respective lower and upper bearing portions 11, 13.

In the above exemplary embodiment described with reference to Figure 3, a blocking device 37 was described as taking the form of a hollow cylindrical tube. However, it will be appreciated that the shape of the blocking device 37 may take other forms. In particular, the inner surface of the blocking device 37 need not provide a cylindrical bore having a circular cross-section, but may instead have other forms of cross-section such as an oval, ellipse, triangle, curvilinear triangle, parallelogram, trapezoid, and so forth. Similarly, the outer surface of the blocking device 37 need not provide a cylindrical shape having a circular cross-section, but may instead have other forms of cross-section.

Whilst the blocking device 37 of the above exemplary embodiment described with reference to Figure 3 has been described with a through-hole 45 having a constant radius which is substantially the same as the radius of the primary bore 5, it wili be appreciated that the through-hoie need not have a constant radius. Instead, the cross-section defining the cylindrical bore and/or the outer shape of the blocking device 37 may vary along the length of the blocking device 37. Furthermore, in some exemplary embodinents, the radius of the through-hole 45 need not be substantially the same as the radius of the aperture 10, but instead may take a smaller or larger value.

In the above exemplary embodiment described with reference to Figures 1 and 3, separate lower bearing portions 11 and upper bearing portions 13 were described. However, it will be appreciated that in other exemplary embodiments, the lower bearing portions 11 and the upper bearing portions 13 may be integrally formed together with the housing 3, such that the bolts 15 are not required. Furthermore, in other exemplary embodiments, the lower bearing portion 11 may be provided separately to the housing 3 and need not be Integrally formed with the housing 3.

The material-spray described herein may use molten metal or any other material suitable for coating an engine component, which may include alloy-type material such as nickel-aluminium.

Industrial applicability

The method described above may be implemented in any structure having a segregated bore, such as a cylinder block crank bore for supporting a crankshaft or a cylinder block bore for supporting a camshaft. The method can be used to facilitate a simpler material-spray operation to take place for building up material on surfaces that define a bore.

Accordingly, the method can be used for facilitating repair of a damaged bore.

The blocking devices 37 prevent material-spray from coating surfaces other than the support portions 9. In particular, the material-spray is substantially confined to the bore which is being sprayed. This prevents other components outside of the relevant bore from being damaged.

Using several blocking devices 37 to fill the gaps along the segregated bore allows the bore to be completely enclosed (except for the ends) . Accordingly, the material-spray process by the material-spray device 49 can be continuous as the material-spray device 49 travels along the bore.

Although exemplary embodiments of the present disclosure have been described herein, it will be appreciated that various improvements and modifications may be incorporated without departing from the scope of the following claims.

Claims

Claims 1. A method of material-spray coating an engine component having a plurality of support portions, each support portion having an aperture therein, the support portions being arranged in a segregated manner along a central axis so that the respective apertures of each support portion cooperate with one another to form a bore along the central axis, the support portions being provided for rotatably supporting another engine component, the method comprising: locating a blocking device between adjacent support portions so that a through-hole of the blocking device cooperates with the respective apertures of the adjacent support portions and so that an inner surface is provided by the adjacent support portions and the blocking device; and moving a material-spray device substantially along the central axis and through the bore so as to allow at least a portion of the inner surface to be coated with material-spray.
2. A method according to claim 1, comprising selectively removing material from the two support portions, prior to locating the blocking device, so that the respective apertures have substantially the same dimensions.
3. A method according to claim 1 or 2, comprising removing the blocking device after the portion of the inner surface has been coated with material-spray.
4. A method according to any preceding claim, comprising selectively removing material from the two support portions, after removal of the blocking device, so that the respective apertures have substantially the same dimensions.
5. A method according to any preceding claim, comprising locating a blocking device between adjacent support portions for each pair of adjacent support portions of the plurality of support portions.
6. A method according to any preceding claim, wherein locating the blocking device between adjacent support portions comprises temporarily deforming the blocking devioe so as to allow insertion of the blocking device between adjacent support portions.
7. A method according to any preceding claim, wherein the engine component is a cylinder block.
8. A method aocording to any preoeding olaim, wherein the bore is a cylinder block crank bore for locating a crankshaft therein.
9. A method aocording to any preoeding olaim, wherein the support portion is a bearing for supporting a portion of a crankshaft.
10. A method according to any of claims 1 to 7, wherein the bore is a camshaft bore for locating a camshaft therein.
11. A method according to claim 10, wherein the support portion is a bearing for supporting a portion of a camshaft. :15
12. A method according to any preceding claim, wherein the blocking device comprises silicon.
13. A method according to any preceding claim, wherein the material-spray comprises metal.
14. A method for repair of a damaged cylinder block bore comprising the method of any of claims 1 to 9.