DESC:FIELD OF INVENTION

The present invention relates to high-speed reamers. In particular, the present invention relates to high-speed reamers for finishing holes in hard components. More particularly, the present invention relates to high-speed reamers suitable for substantially reducing the cycle-time for finishing holes in hard components at low cost.

BACKGROUND OF THE INVENTION

The reamers presently used for finishing holes made in hard components, e.g. cylinder head, normally use feeds of about 0.10 mm/revolution with the presently available tools. This results in very low-production per day, i.e. of the order of just about 100 meters per day. Any attempt to increase the feed with the presently available tools results in poor quality products, such as the roundness and concentricity of the holes reamed in such hard components with respect to the valve guide is not up to the desired accuracy. Moreover, the tool-setting time for this is also very high and requires high operator-skills.

DISADVANTAGES WITH THE PRIOR ART

During the analysis of the process presently being used for finishing holes made in hard components, it was observed that:

1. The cycle time of valve guide is 80% of the total Cycle Time of cylinder head valve guide and valve seat machining, because the valve guide tool travels by about 85 mm (with a feed of 0.10mm /revolution), whereas the valve seat tool travels just about 2 mm. Therefore, it is necessary to reduce the cycle time of valve guide machining.

2. The attempts were made by using high speed and feed with the existing tools, however the critical quality parameters such as desired circularity and concentricity of the holes reamed with respect to the valve guide could not be achieved.
3. Due to heavy load, the reamer is often broken and reamer life is reduced, which is far below the required reamer life of about 100 meters per reamer.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a high-speed reamer for finishing holes made in hard automotive components.

Another object of the present invention is to provide a high-speed reamer for finishing holes requiring substantially reduced cycle time.

Still another object of the present invention is to provide a high-speed reamer for finishing holes made in hard automotive components, which have desired circularity with respect to the valve guide.

Yet another object of the present invention is to provide a high-speed reamer for finishing holes made in hard automotive components, which have desired concentricity with respect to the valve guide.

A further object of the present invention is to provide a high-speed reamer for finishing holes with highly accuracy made in hard automotive components, which are high in accuracy.

A still further object of the present invention is to provide a high-speed reamer for finishing holes made in hard automotive components, which is inexpensive to manufacture.

These and other objects and advantages of the present invention will become more apparent from the following description when read with the accompanying figures of drawing, which are, however, not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a high feed reamer for finishing holes in hard components for reducing the cycle time, comprising:

• a straight cylindrical shank of a predetermined length and diameter;

• another shank having a smaller length and diameter than the straight shank connected thereto by a tapered profile; the smaller shank having a plurality of flutes formed thereon;

• a central coolant hole made throughout the reamer to supply coolant at the tool tip with a coolant hole opening at the front end thereof for flushing out the coolant therefrom for cooling the cutting point by reducing the abrasive resistance of the cutting material;

wherein said plurality of flutes are disposed at unequal angles around said smaller shank by means of different indexing for minimizing the axial load on the reamer with the same basic reamer geometry.

Typically, the coolant hole opening comprises a 100-opening configured at the tool tip angle for flushing out the coolant to obtain an optimum cooling thereof.

Typically, the multi-flute configuration by differential indexing comprises at least six (6) unequal flutes preferably disposed at 500, 600 and 700 respectively.

Typically, the reamer achieves a surface finish of 0.8 Ra at an increased feed rate of 250 m/min for reaming the valve guide holes in the automotive cylinder heads.

Typically, the reamer comprises radial margin with a residual angle at the tool tip for obtaining accurately sized holes and surface finish of the holes reamed in the machined component.

Typically, the tool tip is chamfered at an angle of 300 and configured with a lead chamfer made of compound angles of 200 and 80 respectively and includes a front angle with 50 primary and 150 secondary components thereof.
Typically, the maximum radial margin of 0.3 to 0.4 mm along the flutes is provided with a residual angle to keep the friction on the outer surface substantially low.

Typically, the run-out setting of the tool is maintained within 0.003mm by using a hydro-grip holder incorporated with the valve seat machining arrangement.

In another embodiment of the present invention, there is also provided a high feed reamer for finishing holes in hard components for reducing the cycle time, comprising:

• a first straight cylindrical shank of a length L and diameter D;

• a second shank having a length l and diameter d smaller than the length L and diameter D of the first shank and connected to the first shank by a profiled section, preferably tapered at 100;

• the second shank having a plurality of flutes, preferably at least six (6) fluted formed thereon; said flutes having a radial margin of about 0.3-0.4 mm for reducing friction on the outer surface thereof;

• a central coolant hole made throughout the reamer to supply coolant at the tool tip for cooling the cutting point by reducing the abrasive resistance of the cutting material;

• the tool tip provided with a coolant hole opening at the front end thereof, preferably opening with a 100 angle for optimally flushing out the coolant therefrom;

wherein said plurality of flutes are disposed on said smaller shank with unequal indexing, preferably disposed at 500, 600 and 700 respectively for minimizing the axial load on the reamer with the same basic reamer geometry.

Typically, the tool-tip lead angle is configured as a compound angle comprising a lead chamfer of 200 and 80 respectively and a front angle having two components, a primary front angle of 50 and a secondary front angle of 150; said compound angle configuration facilitating the conversion of the radial force into axial force for direct transfer to the spindle head.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, which include:

Figure 1a shows the front view of the special reamer configured in accordance with the present invention.

Figure 1b shows the special reamer of Figure 1a when viewed from the reamer tip.

Figure 1c shows a typical metal cutting operation using the special reamer of Figure 1a.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, different embodiments of the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1a shows the front view of the special reamer configured in accordance with the present invention. The straight reamer has a length L (e.g. 120 mm) with a main straight round shank of diameter D (e.g. Ø 10h6) and length L1 (e.g. 22.5 mm). The flutes are formed on a smaller shank dimeter d1 (e.g. Ø 7.8 mm – 0.05 mm) which is joined to the main shank by a profiled portion tapered at angle a1 (e.g. 100). In contrast to the tool-tip having a coolant hole puncturing at an angle of 200 in the conventional direct cooling of the tool-tip, the coolant hole CH (Ø 0.3 mm) is punctured here at 100 for flushing out. This additional feature facilitates the special reamer to withstand the abrasive resistance of the tungsten carbide material and to have long lip profile and better cooling at the cutting point. The flutes of unequal indexing (e.g. 500, 600, 700) are formed over the length L2 (e.g. 48 mm) from the tip pf the reamer, which is tapered by an angle a2 (e.g. 300). Reamer flutes have an enlarged diameter d2 of the tip for a length L3 (e.g. 30 mm) for actual metal cutting/reaming operation. The radial margin dm (e.g. 0.3 to 0.4 mm) with a residual angle is provided to ensure the accurate size and surface finish of the final hole, e.g. in cylinder head machined.

Figure 1b shows the special reamer of Figure 1a when viewed from the reamer tip. Here, an unequal indexing of the flutes (number of flutes n = 6) is provided for minimizing the axial load on the special reamer. The width of the cylindrical land x.CL (x = 0.4) is highlighted hatched in pink colour. The flutes are indexed at a6 (e.g. 500), a7 (e.g. 600), and a8 (e.g.700) respectively. This new reamer configuration facilitates in reaching higher feed of 250 m/min with surface finish of 0.8 Ra and thereby to configure longer lip profile and improved cooling at the cutting point of the special reamer.

Figure 1c shows a typical metal cutting operation using the special reamer of Figure 1a. The width of the cylindrical land x.CL (x = 0.4) e.g. removes about 0.20 mm thick metal by using tool tip chamfered at an angle a3 (e.g. 300) and configured with a lead chamfer made of compound angles a4 (e.g. 200) and a5 (e.g. 80) respectively and having a front angle with 50 primary and 150 secondary components. The maximum radial margin of 0.3 to 0.4 mm along the flutes is provided with a residual angle to ensure the size and surface finish of the machined valve guide by keeping the friction on the outer surface substantially low.

DESCRIPTION OF THE PRESENT INVENTION

Accordingly, the major challenge with the presently available reaming tools used for finishing holes made in hard automotive components such as cylinder heads is to substantially reduce the cycle time by suitably increasing the feed. This feed can be increased by increasing the number of effective cutting edges in the reamer.

The tool-setting operation needs to be very operator-friendly and to facilitate operators with low skill to easily perform this tool-setting operation. In addition, the cost of the tool or reamer should be as low as possible.
The problem with designing such an improved reamer is that the reamers generally available in market have a lead angle of 45° with single chamfer of 8° primary angle and 18° secondary angle. It was seen that instead of penetrating the work piece, the conventional lead angle of 45° deflected the tool. Therefore, it was felt necessary that reamer design should facilitate a minimal load at high feed.

Accordingly, the improvement was achieved by making the front lead angle to be less than 45°, so that the radial force on the tool is minimal. Simultaneously, the radial margin over the diameter is to take care of the desired surface finish. Vc of 45-60 M/min is recommended (i.e. RPM 1800-2600 for reamer diameter of 8.5 mm) with a load per tooth 0.02 mm per flute, with a 6-flute reamer. The recommended feed is 250 m with a surface finish of 0.8 Ra. In addition, the run-out setting of the tool is maintained within 0.003mm. This can also be achieved by using a Hydro-grip Holder with the possibilities of valve seat machining, i.e. Special Hydro Grip Holder is incorporated with the Valve Seat Machining facilities.

Accordingly, the feed of the valve guide machining needs to be increased for reducing the cycle-time. This is successfully achieved by using a Multi-edge cutting tool, i.e. a special reamer (Fig. 1b).

Moreover, there is also the task of controlling the Run-out setting of the tool. This is also achieved by using a Hydro-grip Holder with the option of Valve seat machining. All in all, the innovative solution consists of:

a) Reamer having at least 6 flutes,

b) Reamer having differentially indexed flutes to minimize axial load.

c) The presently available and used reamers for similar operations have a single 450 chamfer and include 80 primary angle and 180 secondary angle.

d) In contrast, in the reamer configured in accordance with the present invention, the radial force acting on the tool is reduced by making the lead angle as a compound angle, i.e. the lead chamfer is 20° and 8° and the Front angle has two components, i.e. primary front angle of 5° and secondary front angle of 15°. By such configuration, the radial force is converted into the axial force directly transferred to the spindle head, which is not present on the reamer.

e) Further, the radial margin is configured to provide a surface finish of the valve guide of the order of 0.8 Ra. A radial margin of 0.3 to 0.4 mm with a residual angle is also provided to ensure the size and surface finish.

f) The differential flute indexing (i.e. a6=500, a7=600 and a8=700) ensures a reduction in axial load and increases the feed by keeping the same basic reamer geometry.

g) By keeping a radial margin of about 0.3-0.4 mm along the flutes, there is low-friction on the outer surface.

h) The desired surface finish is easily achieved.

i) A coolant hole puncturing is done at 100 to flush out any coolant, which is different from the existing 200 angle for direct cooling of the reamer cutting tip, thereby the heat generation during high feed is reduced, hence the cutting profile withstands the abrasive resistance of the Tungsten Carbide material.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The high-speed reamer for finishing holes requiring substantially reduced cycle time configured in accordance with the present invention has the following advantages:

• Reamer includes at least 6 flutes.

• Reamer includes differentially indexed flutes to minimize axial load.

• Reamer includes 80 primary Angle and 180 secondary angle.

• Lead angle is 20° and 8°.

• Front angle has a primary front angle of 5° and a secondary front angle of 15°.

• Radial margin is configured to provide surface finish of 0.8 Ra with an increased feed of 250 m/min.

• Radial margin of 0.3 to 0.4 mm with a residual angle is provided to ensure the size and surface finish.

• Reduces axial load by differential flute indexing and increases the feed while keeping the same reamer geometry.

• Radial margin of 0.4 mm along the flutes ensures low-friction on the outer surface.

• The desired surface finish is easily achieved.

• A 100-coolant hole puncturing to have long lip profile and better cooling at the cutting point.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.

The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.

It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, the skilled person will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments described herein and can easily make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies, assemblies and in terms of the size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention. ,CLAIMS:We claim:

1. A high feed reamer for finishing holes in hard components for reducing the cycle time, comprising:

• a straight cylindrical shank of a predetermined length and diameter;

• another shank having a smaller length and diameter than the straight shank connected thereto by a tapered profile; the smaller shank having a plurality of flutes formed thereon;

• a central coolant hole made throughout the reamer to supply coolant at the tool tip through the coolant hole opening made at the front end thereof for flushing out the coolant therefrom for cooling the cutting point by reducing the abrasive resistance of the cutting material;

wherein said plurality of flutes are disposed at unequal angles around said smaller shank by means of different indexing for minimizing the axial load on the reamer with the same basic reamer geometry.

2. High feed reamer as claimed in claim 1, wherein the coolant hole opening comprises a 100-opening configured at the tool tip angle for effectively flushing out the coolant to obtain an optimum cooling thereof.

3. High feed reamer as claimed in claim 1, wherein the multi-flute configuration by differential indexing comprises at least six (6) unequal flutes preferably disposed at 500, 600 and 700 respectively.

4. High feed reamer as claimed in claim 1, wherein the reamer achieves a surface finish of 0.8 Ra at an increased feed rate of 250 m/min for reaming the valve guide holes in the automotive cylinder heads.

5. High feed reamer as claimed in claim 1, wherein the reamer comprises radial margin with a residual angle at the tool tip for obtaining accurately sized holes and surface finish of the holes reamed in the machined component.

6. High feed reamer as claimed in claim 1, wherein preferably the tool tip lead angle is chamfered at an angle of 300 and configured with a lead chamfer made of compound angles of 200 and 80 respectively and includes a front angle with 50 primary and 150 secondary components thereof.

7. High feed reamer as claimed in claim 1, wherein preferably the maximum radial margin of 0.3 to 0.4 mm along the flutes is provided with a residual angle to keep the friction on the outer surface substantially low.

8. High feed reamer as claimed in claim 1, wherein the run-out setting of the tool is maintained within 0.003mm by using a hydro-grip holder incorporated with the valve seat machining arrangement.

9. A high feed reamer for finishing holes in hard components for reducing the cycle time, comprising:

• a first straight cylindrical shank of a length L and diameter D;

• a second shank having a length l and diameter d smaller than the length L and diameter D of the straight shank connected to the first shank by a profiled section, preferably tapered at 100;

• the second shank having a plurality of flutes, preferably at least six (6) flutes formed thereon; said flutes having a radial margin of about 0.3-0.4 mm for reducing friction on the outer surface thereof;

• a central coolant hole made throughout the reamer to supply coolant at the tool tip for cooling the cutting point by reducing the abrasive resistance of the cutting material;

• the tool tip provided with a coolant hole opening at the front end thereof, preferably opening with a 100 angle for optimally flushing out the coolant therefrom;

wherein said plurality of flutes are disposed on said smaller shank with unequal indexing, preferably disposed at 500, 600 and 700 respectively for minimizing the axial load on the reamer with the same basic reamer geometry.
10. High feed reamer as claimed in claim 9, wherein the tool-tip lead angle is configured as a compound angle comprising a lead chamfer of 200 and 80 respectively and a front angle having two components, a primary front angle of 50 and a secondary front angle of 150; said compound angle configuration facilitating the conversion of the radial force into axial force directly being transferred to the spindle head.

Dated: this day of 30th May, 2016. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT