AU683895B2 - Camshaft bearing surface linishing tool - Google Patents

Description

DPI DATE 17/01/95 APPLN. ID 69901/94 AOJP DATE 23/02/95 PCT NUMBER PCT/AU94/00333 AU9469901 (51) International Patent Classification 5: (11) international Publication Number: WO 95/00293 B24D 9/04, B24B 15100 Al (43) International Publication Date: 5 January 1995 (05.01.95) (21) International Application Number: PCT/AU94100333 (81) Designated States: AM, AT, AU, BB, BG, BR, BY, CA, CH, CN, CZ, DE, DK, ES, F1, GB, GE, HU, JP, XE-, KG, XP, (22) International Filing Date: 20 June 1994 (20.06.94) KR, KCZ, LKr, LU, LV, MD, MG, MN, MW, NL, NO, NZ, PL, PT, RO, RU, SD, SE, Si, SIC, TI, r, UA, US, UZ, VN, European patent (AT, BE, CH, DE, DK., ES, ,FR, GB, Priority Data-, GR, IT, LU, MC, NL, PT, SE), QAPI patent (BF, B1, PL 9499 18 June 1993 (18.06.93) AU CF, CG, CI, CM, GA, GN, MS, WR NE, SN, TD), TG), (71)(72) Applicant and Inventor: EASTWOOD, James, Norman Published [AU/AU1; Box No. 13, 65 Patterson Road, Moorabbin, V'IC With international search report.

3189 Before the expiration of the time limit for amending the claims and to be repablished in the event of the receipt of amendments.

(54) Title: CAMSHAFT BEARING SURFACE LiNISHING TOOL (57) Abstract To this end, there is provided a linishing tool for reconditioning a camshaft integral bearing surface of a cylinder head includig an elongate body having an outer surface at least a portion of the outer surface of the body being a linishing surface and at least one handle provided at an end of the body, the body having at least one cylindral section with a latetal cross section having a diameter coresponding to the required bearing diameter of the camshaft integral bearing surface, 'The metal finshing process of ilnshing' involves the use of 4 surface covered by fine particles of hard material which acts as an abraive for the removal of matter by scratching and grinding. This is distinguished from line borers, reamers and files which all use a cutting action to remove material -1- CAMSHAFT BEARING SURFACE LINISHING TOOL This invention relates to a linishing tool for use in the reconditioning of cylinder heads of internal combustion piston engines.

A common problem with internal combustion piston engines is that the cylinder head can become warped due to adverse operating conditions leading to localised hot spots in the cylinder head and/or unbalanced forces or pressures acting on the head.

A warped cylinder head needs to be reconditioned to bring the clearances substantially back into specification before it can be reused.

During reconditioning, the integral camshaft bearing surfaces supporting the overhead camshaft may need to be realigned. The current procedure for realigning the bearing surfaces is to use a line borer to ream the "camshaft tunnel" to the required clearance. The line borer is essentially a metal cutting tool which requires the cylinder head to be accurately secured in position relative to the line borer before the procedure can be conducted. Realigning camshaft integral bearing surfaces is therefore at present a time consuming procedure.

It is an object of the invention to provide a relatively simple tool for realigning camshaft integral bearing surfaces which will reduce the time required to conduct this procedure.

According to the present invention there is provided a linishing tool for 20 reconditioning a camshaft integral bearing surface of a cylinder head comprising an elongate body and at least one handle provided at an end of the body, wherein the elongate body comprises at least one cylindrical section having on its outer surface a linishing surface in the form of a non-removably fixed spiral band circling the cylindrical section, and wherein the cylindrical section has a lateral cross-section having 25 a fixed diameter over the entire linishing surface said diameter corresponding to a required bearing diameter of the camshaft integral bearing shaft.

The "required bearing diameter" is the radius of curvature of the integral bearing surface which enables the surface to support a camshaft without binding of that camshaft when fitted.

The metal finishing process of "linishing" involves the use of a surface covered by fine particles of hard material which acs as an abrasive for the removal of matter

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-2by scratching and grinding. This is distinguished from line borers, reamers and files which all use a cutting action to remove material.

A substantial portion of the body outer surface may comprise the linishing surface. The linishing surface, in the form of a spiral band ci cling the cylindrical section(s), may preferably cover about 50% of the outer surface of the elongate body.

In another alternative, the linishing surface may comprise substantially the entire outer surface of the elongate body.

The elongate body may be provided by a plurality of cylindrical sections arranged in a row with their axes of symmetry co-axial with a common elongate axis of the body. The diameter of the lateral cross-section of each cylindrical section may preferably decrease sequentially from one end of the body to the end thereof. The diameter of the lateral cross-section of each cylindrical section corresponds to the required bearing diameter of a particular camshaft integral bearing surface of the cylinder head. A range of linishing tools can therefore be produced for different production cylinder heads, even in the case where the bearing diameters of each integral bearing surface varies on a particular cylinder head.

A handle may be provided at opposing ends of the elongate body the handles may be substantially cylindrical and may have a lateral cross-section with a diameter less than the diameter of the cylindrical section with the smallest diameter.

20 Preferred examples of the present invention will hereinafter be described with reference to the accompanying drawings, in which: Figure 1 is a side elevation view of one example of a linishing tool according to the invention; and •Figure 2 is a detailed side view of an other example of the linishing tool of the 25 present invention.

Referring initially to the linishing tool shown in Figure 1, the linishing tool includes an elongate cylindrical body 1 having an outer surface 2. At least a portion g of the outer surface 2 is in the form of a linishing surface 3. In the illustrated example, the linishing surface 3 is in the form of a spiral circling the body 1 from one end to the opposing end thereof. The linishing surface 3 preferably covers about 50% of the outer surface. The advantage of having a linishing surface

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WO 95/00293 PCT/AU94/00333 "3" 3 covering only a portion of the body outer surface 2 is that the smooth surfaces 4 between the linishing surfaces 3 provide a discharge path for material removed by the linishing tool.

Nevertheless, it is also envisaged that the linishing surface 3 comprise substantially the entire outer surface 2.

The diameter of the elongate body 2 corresponds to the required bearing diameter of the camshaft integral bearing surfaces of the cylindrical head. Where the bearing diameters of each bearing surface varies sequentially along the cylinder head, the body 1 may include a plurality of cylindrical sections 7, 8 as shown in a detail view in Figure 2 with the diameter of the lateral cross-section of each section corresponding to the required bearing diameter of a particular bearing surface. The axis of symmetry of each cylindrical section 7, 8 are co-axial with a common elongate axis of the body 1. The cylindrical section diameters can decrease in diameter sequentially from one end of the body 2 to the other end thereof providing a series of stepped changes in diameter. A range of linishing tools can therefore be produced to suit the varying camshaft bearing diameters already in production cylinder heads.

Handles are provided at opposing ends of the elongate body 1 and are cylindrical in form. The lateral cross-section of each handle 5 has a diameter less than that of the lateral cross section of the cylindrical section with the smallest diameter.

The linishing tool is used by placing the elongate body 1 of the tool in the "camshaft tunnel" as defined by the integral bearing surfaces, and by moving the tool in a direction parallel to its elongate axis and/or rotating the tool about the axis so that the linishing surfaces 3 abrades the bearing surface removing all of the "high spots" therein which would cause binding of the camshaft if not removed Although the illustrated example shows handles for manual use of the linishing tool, it is also envisaged that the linishing tool be motor driven.

As the linishing tool works on all the bearing surfaces simultaneously, the bearing surfaces are aligned more quickly than by the known procedure. Furthermore, because the tool is dimensioned to the required bearing diameter(s), and because the linishing process provides a smooth finish, the bearing surfaces are more accurately finished to the required clearance.

The linishing tool can be machined from a single bar of bright steel or from mild steel which is then nickel plated. The handles 5 would therefore be integral with the elongate body 1. The linishing surface is applied to the outer surface of the body 1 by known means, the abrasive material preferably being silicon carbide (commonly known "carborundum") or SUBSTrIUTE SHEST (Rule 26)

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WO 95/00293 PCT/AU94/00333 "4" diamond dust, although other materials are also envisaged. It is also envisaged that the handles be made separately from the elongate body. Alternatively, if the linishing tool is to be used only a few times, then the tool could be made of wood with an abrasive coating applied using adhesive on the body.

sUBSTITUT SHEET (Rule 26)

Claims (9)

1. A linishing tool for reconditioning a camshaft integral bearing surface of a cylinder head comprising:- an elongate body and at least one handle provided at an end of the body; wherein the elongate body comprises at least one cylindrical section having on its outer surface a linishing surface in the form of a non-removably fixed spiral band circling the said cylindrical section; and wherein the cylindrical section has a lateral cross- section having a fixed diameter over the entire linishing surface said diameter corresponding to a required bearing diameter of the camshaft integral bearing shaft.

2. A linishing tool according to Claim 1 in which the diameter of the cylindrical section is manufactured to a tolerance of plus or minus 0.0002 inches of the required bearing diameter of the camshaft integral bearing surface.

3. A linishing tool according to Claims 1 or 2 in which the linishing surface covers about 50% of the cylindrical section.

4. A linishing tool according to Claims 1, 2 or 3 in which the elongate body has a plurality of cylindrical sections arranged in a row with their axes of symmetry co-axial I: with a common elongate axis of the body and wherein the diameter of the lateral cross-section of each cylindrical section corresponds to the required bearing diameter of a particular camshaft integral bearing surface of the cylinder head. A linishing tool according to Claim 4 in which the diameter of the lateral cross-section of each cylindrical section decreases sequentially from one end of the body SRA 4 N to the other end thereof.

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6. A linishing tool according to any preceding claim in which a handle is provided at opposing ends of the elongate body.

7. A linishing tool according to any preceding claim in which a handle is substantially cylindrical and has a lateral cross-section with a diameter less than the diameter of the cylindrical section with the smallest diameter.

8. A linishing tool according to any preceding claim in which one or both of the handles is adapted to engage drive means so that the linishing tool may be motor driven.

9. A linishing tool according to any preceding claim in which the linishing surface comprises a diamond dust abrasive compound. A linishing tool according to any preceding claim which comprises a cylindrical section of lateral cross-section diameter of 27mm, 29mm, 30mm, 32mm '3mm, 34mm or 38mm. 1. A linishing tool for reconditioning a cam shaft integral bearing surface of a cylinder head, the tool being o substantially as herein described, with reference to, and as shown in Figure 1 or Figure 2 of the accompanying drawings. o DATED THIS 4TH DAY OF AUGUST 1997 SANDERCOCK AND COWIE PATENT ATTORNEYS FOR NORMAN JAMES EASTWOOD