A METHOD OF MANUFACTURING A DIE AND A DIE THEREOF
TECHNICAL FIELD
The disclosure relates to field of cold forging header, more particularly relates to a process of designing a die used for cold forging header.
BACKGROUND
The disclosure relates to a process of designing a die for cold forging header. Basically, these trim dies are interchangeable tools in the header machine, mostly used in the fourth station punch side during final trimming stage. These trim dies tool life is vital, since lesser tool life or premature failure of these trim dies leads to unwanted tool change time loss, finally leading to lower productivity. So, it is very much important to have a better optimized tool life for these trim dies. The trim dies design is optimized with cutting edge geometry, trimming hob angle, outer relief geometry, and smooth surface of the metal working areas during trimming, thereby to offer almost zero resistance for the material to flow, thereby enhancing the trim die tool life. This optimized trim dies are manufactured through a specially designed process, which stands unique to the conventional manufacturing processes. The disclosure provides for a design process for hexagonal trim dies manufacturing with a specific sequence of operations to achieve required designed specifications and configurations. The disclosure also provides for a process controls and checks for the manufacturing process design of hexagonal trim dies.
In the existing conventional process of manufacturing Trim dies, the Cutting edge is filed manually, leaving behind a uneven radius, which leads to irregular trimming action causing premature failure of the trim dies with cutting edge getting chipped off.
The disclosure address the tool life problem of trim dies, and is aimed at overcoming the existing lesser tool life problem by a specially designed process for manufacturing the hexagonal trim dies configuration and specifications. Thus, a higher hexagonal trim dies tool life is achieved which is almost double the existing tool life. By this process, the hexagonal trim die tool change time loss is drastically reduced and thereby increasing the productivity significantly. Due to the tool life improvement, an additional benefit of reduced tool cost per 2
piece is accomplished. Also, the hexagonal trim dies consumption has got reduced drastically, thereby reducing the total tool manufacturing cost.
STATEMENT OF THE DISCLOSURE
Accordingly, the disclosure relates to a method of manufacturing a die (1), said method comprising acts of preparing die-blank (1a) using predetermined processes, hobbing and face turning the die-blank (1a) to obtain desired shaped profile (2), angular face turning the die-blank (1a) to obtain tapered top surface (1b), developing plurality of outer relief (1d) on the tapered top surface (1b) and land portions (2c) on the profile (2) by grinding, developing uniform negative rake (2b) on cutting edges (2a) of the profile (2) by sparking, lapping and polishing to improve surface roughness of the die-blank (1a), and extrude honing the die-blank (1a) to improve surface roughness of the die (1); and also relates a die (1) comprising a base (1c) and tapered top surface (1b), a predetermined profile (2) of axial opening at the tapered top surface (1b) extending till the base (1c), plurality of land portions (2c) at the opening is being configured as cutting edges (2a) of the die (1), wherein said cutting edges (2a) comprise negative rake (2b) to enable uniform loading of the die (1) onto a work piece, and plurality of outer relief (1d) on the top surface (1b) extending from the land portions (2c).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.
FIG. 1 shows the sectional view of the die of prior art,
FIG. 2 shows the sectional view of the die according to the present invention,
FIG. 3 shows perspective view of the die according to instant invention,
FIG. 4a and 4b shows top and bottom views of the die according to instant invention,
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FIG. 5 shows the sequential operations of turning, annealing, hobbing, polishing, coating, and OAL facing of the die-blank according to instant invention,
FIG. 6 shows the sequential operations of annular turning, grinding of the die-blank according to instant invention,
FIG. 7 shows the sequential operations of sparking, lapping & polishing of the die-blank according to instant invention, and
FIG. 8 shows the sequential operations of extrude honing, de-magnetizing, CVD coating, vacuum hardening and tempering, extrude honing and grinding of the die-blank to obtain the die according to instant invention.
DETAILED DESCRIPTION
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.
This disclosure is drawn, inter alia, to method of manufacturing die and a die.
The principal embodiment of the present disclosure relates to a method of manufacturing a die (1), said method comprising acts of preparing die-blank (1a) using predetermined processes, hobbing and face turning the die-blank (1a) to obtain desired shaped profile (2), angular face turning the die-blank (1a) to obtain tapered top surface (1b), developing plurality of outer relief (1d) on the tapered top surface (1b) and land portions (2c) on the profile (2) by grinding, developing uniform negative rake (2b) on cutting edges (2a) of the profile (2) by sparking, lapping and polishing to improve surface roughness of the die-blank
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(1a), and extrude honing the die-blank (1a) to improve surface roughness of the die (1).
In yet another embodiment of the present disclosure said preparing processes comprises sequential operations of turning, annealing, drilling, polishing, and coating.
In still another embodiment of the present disclosure said annealing is carried-out to a predetermined value of 15 Rc max.
In still another embodiment of the present disclosure said polishing is on inner and outer surfaces of the die-blank (1a).
In still another embodiment of the present disclosure the hobbing comprise extrusion of the die-blank (1a) using a hob of Molybdenum-2 material to obtain hexagonal bore profile (2d).
In still another embodiment of the present disclosure the land portions (2c) are obtained by grinding on hexagonal bore profile (2d).
In still another embodiment of the present disclosure the improved surface roughness of about 0.05 Ra is obtained by the lapping and the polishing.
In still another embodiment of the present disclosure said method comprises finishing operations of demagnetizing, CVD coating, vacuum hardening, and tempering subsequent to the lapping and the polishing processes.
In yet another principal embodiment of the present disclosure a die (1) comprising a base (1c) and tapered top surface (1b), a predetermined profile (2) of axial opening at the tapered top surface (1b) extending till the base (1c), plurality of land portions (2c) at the opening is being configured as cutting edges (2a) of the die (1), wherein said cutting edges (2a) comprise negative rake (2b) to enable uniform loading of the die (1) onto a work piece, and plurality of outer relief (1d) on the top surface (1b) extending from the land portions (2c).
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In still another embodiment of the present disclosure said die (1) is preferably cylindrical in shape comprising circular outer surface and hexagonal inner surface.
In still another embodiment of the present disclosure the die (1) material is Molybdenum steel selected from a group comprising M2, M4 and M35.
In still another embodiment of the present disclosure the shape of axial opening is a hexagon with cutting edges (2a).
In still another embodiment of the present disclosure the negative rake (2b) has width ranging about 0.19 mm to about 0.21 mm, depth of about 0.09 mm and angle ranging about 24o to 26o.
Hexagonal Trim dies are used to trim upsetted (cold forged) blanks into required hexagon shape of desired size. The hexagonal trim dies are part of interchangeable tools for every part size. The tool life of the hexagonal trim dies is vital, since this determines the productivity, which in turn being influenced by tool change downtime as well. Lesser the tool change time, higher the productivity. By increasing the tool life of the hexagonal trim dies, the tool consumption will come down, thereby reducing the tool change down time. This will result in higher productivity. The key to increase the hexagonal trim die tool life is to have an optimized design for the trim die and to provide suitable process design to suffice the new design requirement.
The metal working areas of the hexagonal trim die was focused and the key areas of trim dies functioning are optimized to have a smooth flow of trimmed flash material. The metal working areas of a Hex trim die are: Land (Hexagonal), Inner relief angle (Hob angle), outer relief angle, and cutting edge chamfer (all around).
The Geometry and the dimensions of the above areas of focus are designed with a special focus on the surface roughness on these areas (FIGS.1 and 2 and Tables 1 & 2), thereby enabling a smooth flow of material during trimming action. Lesser the resistance to the material flow, higher the tool life. The
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process is designed to achieve the desired Geometry and surface roughness on these metal working areas.
FIG 3 and FIG. 4a & 4b illustrates perspective view, top and bottom views of the die respectively according to instant invention.
Table 1
Parameters
Prior art
Instant invention
Land
0.80/1.00
1.08/1.16
Outer Relief
NIL
30o/31o
Inner Relief
4o
2.5o/3.0o
Cone angle
15o
35o
Edge Radius (All around)
Non-uniform Radii R0.1
0.20x24.5o Chamfer
Table 2
Parameters
Prior art
Instant invention
Land
0.84
0.05
Outer Relief
0.92
0.4
Inner Relief
0.86
0.4
Cone angle
1.54
1.00
The process comprises the sequence of operations by referring to FIGS 5 to 8, are; turning die-blank, annealing the die-blank to 15 Rc max, hobbing die-blank, polishing through bore & taper bore, coating zinc phosphate on the die-blank, hobbing & OAL (Over All Length) facing, angular face turning & OD turning, grinding on OAL, outer relief and land, sparking negative rake on the cutting edge & Polish the negative rake, lapping & polishing, extrude honing the hobbed area & outer relief, de-magnetizing, CVD coating, vacuum hardening & tempering, extrude hone the hobbed area & outer relief, grinding the OD, de-magnetizing, and final inspection for packing & dispatch.
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The steps as mentioned above are in the process of designing the trim-die to achieve the desired results. The hobbing process involves a forward extrusion (cold forming) technique to form the desired size of hexagonal profile on to the trim die blank. A Hob of M2 material with a surface finish of about 0.04 Ra max on the hex profile is used to hob the trim die-blank, in a hydraulic press. A lubricant is applied on the die bore and the hob prior to hobbing. The facing stock on the die blank is arrived at, considering the required Hex size. The hobbing process is very critical to achieve the desired size of the hexagon head profile of the screw or bolt during trimming operation.
In the process of hex trim die a negative rake of 0.2 x 25° is sparked on the cutting edge by using a special hexagonal cone electrode, precisely sparking the negative rake for a resultant depth of 0.09 mm, which results in a uniform chamfer all around the cutting edge of hexagonal profile. The negative rake enables a uniform loading of the trim die during trimming action, and also the edges are strengthened due to the increased area of cutting edge as a result of negative rake. Thus negative rake is one of the principal embodiments of the hexagonal trim die which improves the trim die life.
Lapping and Polishing is a super-finished process carried out to improve the surface roughness of the hex trim die. The flatness of the trim die top face is improved by Lapping and polishing process carried out in a Lapping & Polishing machine. The Flatness of 5 microns is achieved by this special process and the surface roughness achieved by this process is 0.05 Ra. This process is designed to result in a perfect smooth surface, thereby enabling a free movement of material during trimming action leading to a longer life of the trim die without causing any scoring marks or damages on the surface of the trim die due to frictional resistance offered by the trim die surface.
Extrude honing is also being carried-out before and after CVD coating and Vacuum hardening & tempering. This is special process of super-finishing utilizing a highly viscous abrasive paste forced to enter the trim die bore and contact the top face and outer relief by means of a double acting piston in a hydraulic press. This abrasive paste compressed at a high pressure behaves 8
like a cutting tool which makes an abrasive action on the metal contact areas of the trim die. In this process, the hobbed hex profile and the outer relief are exposed to the abrasive action and as a result of which the surface roughness of the hobbed hexagonal profile area and the outer relief areas are improved to a value of 0.4 Ra.
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two 9
recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
Referral Numerals:
1: die,
1a: die-blank,
1b: tapered top surface,
1c: base,
1d: outer relief,
2: profile,
2a: cutting edges,
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2b: negative rake,
2c: land portions,
2d: hexagonal bore profile, and
2e: inner relief.
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We claim:

1. A method of manufacturing a die (1), said method comprising acts of:
a. preparing die-blank (1a) using predetermined processes,
b. hobbing and face turning the die-blank (1a) to obtain desired shaped profile (2),
c. angular face turning the die-blank (1a) to obtain tapered top surface (1b),
d. developing plurality of outer relief (1d) on the tapered top surface (1b) and land portions (2c) on the profile (2) by grinding,
e. developing uniform negative rake (2b) on cutting edges (2a) of the profile (2) by sparking,
f. lapping and polishing to improve surface roughness of the die-blank (1a), and
g. extrude honing the die-blank (1a) to improve surface roughness of the die (1).

2. The method as claimed in claim 1, wherein said preparing processes comprises sequential operations of turning, annealing, drilling, polishing, and coating.

3. The method as claimed in claim 2, wherein said annealing is carried-out to a predetermined value of 15 Rc max.

4. The method as claimed in claim 2, wherein said polishing is on inner and outer surfaces of the die-blank (1a).

5. The method as claimed in claim 1, wherein the hobbing comprise extrusion of the die-blank (1a) using a hob of Molybdenum-2 material to obtain hexagonal bore profile (2d).

6. The method as claimed in claims 1 and 5, wherein the land portions (2c) are obtained by grinding on hexagonal bore profile (2d).

7. The method as claimed in claim 1, wherein the improved surface roughness of about 0.05 Ra is obtained by the lapping and the polishing.

8. The method as claimed in claim 1, wherein said method comprises finishing operations of demagnetizing, CVD coating, vacuum hardening, and tempering subsequent to the lapping and the polishing processes.

9. A die (1) comprising:
a. a base (1c) and tapered top surface (1b),
b. a predetermined profile (2) of axial opening at the tapered top surface (1b) extending till the base (1c),
c. plurality of land portions (2c) at the opening is being configured as cutting edges (2a) of the die (1), wherein said cutting edges (2a) comprise negative rake (2b) to enable uniform loading of the die (1) onto a work piece, and
d. plurality of outer relief (1d) on the top surface (1b) extending from the land portions (2c).

10. The die (1) as claimed in claim 9, wherein said die (1) is preferably cylindrical in shape comprising circular outer surface and hexagonal inner surface.

11. The die (1) as claimed in claim 9, wherein the die (1) material is Molybdenum steel selected from a group comprising M2, M4 and M35.

12. The die (1) as claimed in claim 9, wherein the shape of axial opening is a hexagon with cutting edges (2a).

13. The die (1) as claimed in claim 9, wherein the negative rake (2b) has width ranging about 0.19 mm to about 0.21 mm, depth of about 0.09 mm and angle ranging about 24o to 26o.