PROCESS FOR PREPARING SEAT PIPE USING HOLLOW PIPES ON
HYDRAULIC PRESS
Field of the present invention;
The present invention relates to the manufacturing a seat pipe by cold extrusion
process wherein the initial material received for billet cutting is hollow metallic
pipe of certain thickness and inner diameter.
Background and object of the present invention;
Seat pipes are very important parts used in automobiles particularly in power
generation/ transmission. One conventional method used for manufacturing seat
pipes involves cold forging which may have its own merits but it is a very time
taking and resource involving process. To perform said forging operation, the
raw material/work-piece is maintained at a suitable temperature, below the
recrystallization temperature of said material used. Trimming is used when a
forming operation leaves material in the form of flash around the edges of the
part. As with punching, blanking and trimming do not create features as precise
as machining but the speed at which it could be done makes it very attractive
when large quantities are involved. However, this process is an expensive
process, particularly in case of large scale production for a longer or continuous
duration. The product manufactured by the conventional process, involves one
or more following drawbacks in its structure and in functionality:
• Lesser tolerance against abrasion;
• Warping of material during the cooling process;
• Undesirable result due to reaction of metal with that of surroundings;
• Varied metal structure;
• After performing the principle steps of product forming, involvement
of several such machining and refining processes, which may
deteriorate the structural strength and functional life;
• In one of the conventional methods for producing such seat pipe, the
cold forging involves complex machinery, sophisticated die designing
and power consuming heavier/powerful equipments.
In light of above mentioned facts and practical experiences of the concerned
field of manufacturing the present invention proposes such a method of
manufacturing seat pipe, which mainly involves cold extrusion operation on
hydraulic cold extrusion former, wherein it utilizes hollow pipes of certain
thickness and iimer diameter for billet forming and using thereafter. The
proposed method herein is a noble effort to get rid of all above mentioned
drawbacks associated with the seat pipe products, manufactured using the
conventional methods. The proposed method provides a good tolerance and
the initial material does not required any specific heat
treatment/conditioning, wherein the said proposed cold extrusion process is
preferably performed at room temperature on the billet. The present method
results in a very finely shaped end product and thus requires lesser number of
effective and easy performing secondary steps towards the product fiiushing.
Thus the forging is a more difficult and time consuming process than the
extrusion, particularly for the concerned seat-pipe product herein. So,
depending upon the specific needs and use of product being manufactured,
the process of manufacturing should be chosen to be economical. So the
process described here in present invention is better in terms of cost and
efforts required.
The main objective of the present invention is to propose a process for
manufacturing seat pipe, which mainly involves cold extrusion operation on
hydraulic cold extrusion former, wherein it utilizes hollow pipes of certain
thickness and inner diameter for billet forming and using thereafter.
Another important object of the present invention is to eliminate any forging
operation, conventionally being performed for the production of a seat pipe,
by essentially performing the extiusion process for the same purpose thereof,
wherein said forging operation might be supported and followed by certain
other steps towards machining, shape refining, strengthening etc. Thus by
such novel improvement in the seat pipe making process substantial
resources, material and time are saved, which is not only economical and cost
effective, but it also proposes a more environment friendly process.
Another object of the present invention is to propose a set of suitable die(s) to
be employed for performing the cold extrusion process on the hydraulically
operated cold extrusion press for manufacturing the seat pipe.
Another object of the present invention is to propose a process for preparing
seat pipe, wherein it involves cold extrusion of the billet to the desired shape
and dimension, wherein said billet is cut from the supplied hollow pipes of
certain thickness and inner diameter.
Another object of the proposed invention herein is propose the seat pipe with
much advanced properties like stress bearing capacity; very high structural
strength and long functional life. For instance, cold formed parts can be made
quickly, with less energy and less scrap. As a result, the costs and lead times
can be reduced by up to 70%. The process also has a number of additional
benefits, capable of consistently producing stronger components with a better
finish.
Statement of the present invention:
The present invention is intended to propose a process for manufacturing seat
pipe, which mainly involves cold extrusion operation on hydraulic cold
extrusion former, wherein it utilizes hollow pipes of certain thickness and
inner diameter for billet forming and using thereafter; and wherein it
proposes:
a process to eliminate any forging operation, conventionally being performed
for the production of a seat pipe, by essentially performing the extrusion
process for the same purpose thereof, wherein said forging operation might
be supported and followed by certain other steps towards machining, shape
refining, strengtheiiing etc.;
a set of suitable die(s) to be employed for performing the cold extrusion
process on the hydraulically operated cold extrusion press for manufacturing
the seat pipe;
a process for preparing seat pipe, wherein it involves cold extrusion of the
billet to the desired shape and dimension, wherein said billet is cut from the
supplied hollow pipes of certain thickness and iimer diameter; and
the seat pipe with much advanced properties like stress bearing capacity; very
high structural strength and long functional life.
Description of the present invention:
The present invention discloses a novel and advanced method of
manufacturing seat pipe component, wherein it involves billet formation,
followed by cold extrusion operations hydraulically on cold former. In the
present process the raw material is in the form of hollow metallic pipe. From
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said raw material, depending upon its thickness and inner diameter therein
and based on the pre-calculated length, inner-diameter, thickness and overall
dimension of the final product, a suitable piece of billet is cut and is subjected
to cold extrusion operation on the hydraulic extrusion press. Such
optimization of the billet size and its overall metal content is necessary to
effectively minimize the loss of material during the proposed manufacturing
process.
The cold extrusion operation upon the billet is performed preferably at room
temperature or optionally at near room temperature. The advantages of such
operation over hot extrusion, which is not at all preferred in the present
proposed process, are the lack of oxidation, higher strength due to cold
working, closer tolerances, good surface finish, and fast extrusion speeds if
the material is subject to hot shortness.
The proposed cold extrusion operation is preferably the direct extrusion,
wherein the die is kept stationary and the ram performs the movement. The
press position is preferably vertical where the ram movement is vertical,
preferably controlled by hydraulic pressing means.
The overall manufacturing process mainly involves followed four steps:
• Cold Extrusion for basic dimension of seat pipe,
• Cold Extrusion for Hex formation followed by shape finalization.
• CNC machining
• Finishing and other process.
The billet, before initiating the extrusion operation, is subjected to certain
chemical treatment, namely bonderizing, towards application of a corrosion
resistant and lubricating coating. Such surface conditioning of the billet not
only improves the surface properties of the final product, but by the lubricant
base layer further supports easy and effective extrusion in cold condition
towards elongation of the hollow seat pipe and shape modification therein.
Bonderizing helps in easy optimization of the hydraulic pressure applicable
for the desired extrusion operation and less power consumption in the
operation; and further supports the whole extrusion operation by enhancing
stress-tolerance by the billet material under operation to avoid any fatigue.
In first part of the cold extrusion operation, the hollow billet piece is
elongated to the desired length with other preferred dimensional parameters,
except creation of final head section.
In next step of the extrusion, a particular set of dies is applied for the purpose
of head formation, wherein one end of the extruded work-piece of the hollow
elongated pipe of first step gets modified to a particular head shape. Said
head section of the work-piece, which is a small pre-calculated portion of the
whole body of the pipe, achieves its outer surface as cylindrical one with
enhanced outer diameter in comparison to rest of the pipe body, while its
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irmer hollow region is extruded in such a way to create a regular hexagonal
surface or near to a hexagonal surface, throughout the length of the head
section therein. In one more step of extrusion process herein, the outer and
iimer shape and configuration of the head section is refined and thus the inner
region of the head section resembles the shape of a little regular hexagonal
tube with open ends.
The material is pushed/drawn through a die of the desired cross-section. The
die assumes the shape of a block with depth, begirming first with a shape
profile that supports the center section. The die shape then internally changes
along its length into the final shape, with the suspended center pieces
supported from the back of the die. The product received after cold extrusion
is then passed through another die-set towards the formation of final product.
In this process another extrusion is used with another die. The dies used for
the process is in hexagonal or near hexagonal form, whichever is optionally
used. The present method mainly focuses on using of two set of dies which
have different parameters in terms of area/dimension and shape.
Unlike in forging and machining, the grain structure of the material being
elongated is forced to follow the contours of the component. Therefore, the
strength of the part is maximized along its length, in much the same way that
a piece of wood is stronger "with the grain".
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Producing components using the cold former process also makes it possible to
achieve a superior finish, both internally and on the surface. Accurate internal
profiles and complex external profiles are possible, enabling precision parts to
be manufactured that can have a significant impact on the performance of the
assemblies and machinery in which they are used.
One preferred schematic scheme for the complete set of presently proposed
seat pipe production process, involving various preferred principle and
secondary steps is being furnished hereinbelow:
Raw Material receipt & inspection (Hollow
metallic pipe of certain thickness and irmer
diameter)
Billet cutting
Cold Extrusion-1
Cold Extrusion-2
(Head section formation: Hex
Forming)
(Principle
steps of the
whole
process)
Pre-Mechining
CNC-l(Tap side M/cng)
CNC-2(Hexagonal Head M/cng)
Cross hole Drilling
Hole Drilling
Thread Tapping
Deburring
Centreless Grinding
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Washing
Final Inspection(Sampling PDI)
Oiling & Packing
Storage in FG store
Dispatch
Pre machining is the term related to the pre inspection of quality and capacity
of machine and product before CNC process.
After completion of the extrusion stage, certain set of machining operations
are performed to enhance the structural and functional properties of the final
product being produced. Such operations mainly include, preferably in stepwise
manner one by one, are: CNC machining (including the tap side as well
as hexagonal head machining), cross hole drilling, hole drilling, thread
tapplin, deburring, centreless grinding, washing, oiling etc.
The CNC in CNC machining stands for Computer Numerical Control.
CNC machining operations involve the use of computers to control machine
tools. Tools that can be controlled in this manner include lathes, mills, routers
and grinders, wherein such processes are more precise than manual
machining, and can be repeated in exactly the same marmer over and over
again. Because of the precision possible with CNC machining, this process can
produce complex shapes that would be almost impossible to achieve with
manual machining.
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After CNQ cross hole drilling is done, in which a bit is used to cut or enlarge
a hole of circular cross-section in solid material. The process of cutting threads
that means the irregularities in the shape, using a tap is called tapping,
whereas the process is called threading. This whole process is called thread
tapping.
Deburring is the most important process in finishing of the present product.
Centreless grinding has paved the way to producing complex and detailed
metal parts without having to grind a hole in the center of the work piece.
Centerless grinding is actually the machining, that uses abrasive cutting to
remove material from the work piece.
Scope of the invention:
Although the invention has been described with reference to specific
embodiments, this description is not meant to be construed in a limiting
sense. Various modifications of the disclosed embodiments, as well as
alternate embodiments of the invention, will become apparent to persons
skilled in the art upon reference to the description of the invention. It is
therefore contemplated that such modifications can be made without
departing from the spirit or scope of the present invention as defined.
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OR - .3325DEL13
We claim; ^ 2 NOV 2013
1. A process for manufacturing seat pipe, which mainly involves cold
extrusion operation on hydraulic cold extrusion former, followed by a set
of stepwise machining operations including CNC machining, cross-hole
drilling, hole drilling, thread tapping, deburring and centreless grinding;
wherein said process is characterized by cold extrusion of a hollow
metallic billet pipe to an elongated seat pipe product with a head section,
created with the hexagonal irmer surface therein.
2. A process for manufacturing seat pipe, as claimed in claim 1, wherein the
cold extrusion is performed on the hollow metallic piece of pipe of certain
thickness and inner diameter, wherein prior to the said cold extrusion
operation said billet preferably receives chemical treatment on its surface,
namely bonderizing.
3. A process for manufacturing seat pipe, as claimed in claim 1, wherein the
said process is characterized by eliminating any forging operation step,
conventionally being performed for the production of a seat pipe, by
essentially performing the extrusion process for the same purpose thereof.
4. A process for manufacturing seat pipe, as claimed in claim 1, wherein said
cold extrusion operation(s) involves set(s) of suitable die(s) to be employed
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ORIGINAL 3 3 2 5 » 1 3
for seat pipe extrusion and the head section formation, including the
hexagonal inner surface profile creation therein. 1 2 NOV 2013
5. A process for manufacturing seat pipe, as claimed in claim 1, wherein cold
extrusion of the billet to the desired shape and dimension is characterized
by cutting the billet from the supplied long hollow pipe of certain
thickness and irmer diameter.
6. A process for manufacturing seat pipe, as claimed in claim 1, wherein said
cold extrusion process preferably involves two steps of extrusion using
two different sets of dies, wherein the first cold extrusion step is primarily
responsible for elongation of the hollow billet piece to the desired length of
the said seat pipe, with other preferred shape and dimensional parameters,
except the final creation of the head section thereof.
7. A process for manufacturing seat pipe, as claimed in claim 1 and claim 6,
wherein the second cold extrusion step is mainly responsible for
finalization of the head section preparation, including the formation of
inner surface of the head section as the regular hexagonal surface therein.
8. A process for manufacturing seat pipe, as claimed in claim 1, wherein the
said cold extrusion operation on horizontal cold former applies one
suitable die for creating main body of the said seat pipe, its major
structural and functional features, while another die is used for major
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surface depressions and structure of the said seat pipe component;
wherein the said embodiment of the seat pipe, created by cold former
undergoes other structural and functional property enhancer operations.
9. A process for manufacturing seat pipe, as claimed in claim 1, wherein the
said method is characterized by formation of optional embodiment of the
said seat pipe, in various optional and different shapes, sizes, dimensions,
features towards functionality of the said pipe, surface pattern and
corvfiguration therein, are manufactured by the present said method
involving the horizontal cold former, using suitable dies of the
corresponding optional shapes, sizes, dimensions, features towards
functionality of the said seat pipe, surface pattern and configuration
therein.