Description:A GRIPPER JAW ASSEMBLY USED IN THE COLD DRAWING PROCESS FOR MANUFACTURING SEAMLESS TUBES’

FIELD OF INVENTION:
[001] The present invention relates generally to the manufacturing of seamless steel pipes. More particularly the invention relates to carriage used for manufacturing seamless tubes by cold drawing process still more particularly the invention relates to gripper jaw assembly used in the cold drawing process.

BACKGROUND OF THE INVENTION:
[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[003] Normally in the manufacturing of the seamless steel tubes, the smaller diameter tube is derived from the bigger size Hollows. For example, if the outside diameter required is 44.5mm, then the outer diameter more than 54.1mm hollow is being used. This method is called the cold drawing process. Outside diameter of the tube is controlled by the Draw Die inside diameter and Wall thickness of the tube is controlled by the Draw Plug. The front end of the hollow is pointed to a diameter less than the inside diameter of the draw die to ease the entry of the larger diameter hollow into the draw die and hold the pointed end with a gripper jaws during drawing process in draw bench. For example, if the Tube outside diameter required is 44.5mm, a Hollow diameter of 54.1mm is pointed to a diameter of 42 mm in the drawing die through gripper jaw in the pointing machine for drawing of the required tube size of 44.5mm outside dimeter.
[004] Cold drawing is done with a Gripper Jaw block, which holds the bigger size hollow and pulls it through the die. The gripper jaw comprises of two halve blocks (Left Block & Right Block) made of Hardened high carbon steel. The drawing force requirement can be as high as 50-tons. This high repetitive force acting on a hardened block results in the formation of fatigue cracks and potentially failure along the various stress concentrating area like sharp corners and bend, gripping teeth and jaw. Frequent failure requires replacement of the gripper jaw block, which increases the production cost. Each failure of block leads to material wastage in the form of damaged tubes and increased cycle time due to time involved for tool change. Further, specific tool can be used only for drawing materials with hardness less than the gripper jaw block. To solve this problem an alternate jig/tool for cold drawing process is required to be devised.

OBJECTS OF THE INVENTION:
[005] It is therefore an object of the present invention to propose a tool to improve the tool life and reduce the failure rate.

[006] Another object of the present invention is tool interchangeability across various drawing bench.

[007] Yet another object of the present invention is to reduce the cycle time of the tool change.

[008] Still another object of the present invention is to reduce the cost of production by reducing the material rejection rate, tool replacement interval and carriage life.

[009] Further another object of the present invention is to provide a gripper jaw assembly which is used as a fixture in the cold drawing process for manufacturing seamless tubes, wherein different tube sizes can be handled with same tool.

[0010] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.

SUMMARY OF THE INVENTION:
[0011] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus/composition and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.

[0012] Top plate comprises of guideway on one side and projection on other side to locate and hold the gripper jaw. This projection is circular in nature. Guideway comprises of multiple holes with counter bore for locking the top plate with connecting block. Bottom plate comprises of projection to locate and hold the gripper jaw. There are plurality of holes with counter bore, two of them for locking with connecting block and two of them for locking the locating plate. Connecting block is a hollow block to connect the top and bottom block. This block has a projection to hold the cylindrical gripper pad in its position. This projection ensures the gripping pad in position. Connecting block comprises of threaded holes to allow the assembly with top and bottom block. Locating block is on the side of connecting block. It has a half radius groove to connect it to a lever which pushes the assembly to and fro. It is connected and held to bottom block through multitude of screws. Gripping pad is a cylindrical block secured in its place by a top, bottom plate and connecting block. Gripping pad is an interchangeable part of the gripper jaw assembly which can be changed based on the tube material and outer diameter (OD). The main function of the gripping pad is to hold the pointed end of hollow.

[0013] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

[0014] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

[0015] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
[0016] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein:-

Figure-1 shows the details of the bottom plate.
Figure-2 shows the details of the connecting block.
Figure-3 shows the details of the cylindrical gripping block.
Figure-4 shows the details of the top plate.
Figure-5 shows the details of the locating block.
Figure-6 shows the assembly of top plate, bottom plate, connecting block, locating block and gripper pad according to the present invention.

[0017] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF PREFERED EMBODIMENT OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS:

[0018] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

[0019] The present invention makes a discourse regarding a gripper jaw assembly used in the cold drawing process for manufacturing seamless tubes.
[0020] Accordingly, the base of the gripper jaw assembly (100) comprises of two halves, both halves are similar in construction. Each half is made with flat block and now it is hence forth called as bottom block (101) by mounting the connecting block (102) in the back side of the bottom block (101) by means of tightening it with mounting bolts (103) with two nos of equally spaced thru bore holes (107). Holes are counter bored from other side to ensure proper seating of bottom plate. There are two nos, of holes with counter bore (108) perpendicular to the earlier hole along one side for mounting the locating block (106). Further, bottom block (101) has a step projection (109) of a circle which is divided into two unequal parts by a chord at a particular distance from the centre. The other part of circle is part of the mating bottom half. To this assembly, the gripping cylindrical block (104) with half radius threads (112) perpendicular to the cylindrical axis is fitted with the connecting block (102) through a groove (111) in the gripping cylindrical block (104) for a depth of 4 mm with diameter of 90 mm. The diameter of half radius threads (112) ranges from 19mm to 76mm to suit different tube sizes. This gripping cylindrical block (104) is inserted to this step (114) on the inside surface of connecting block (102). The recession (110) in the bottom of gripping cylindrical block (104), along the axis will make the perfect seating with step projection (109) on bottom block (101) so that during the return stroke, the gripping cylindrical block (104) will not come out of the gripper jaw assembly (100) which is used in the forward stroke for drawing operation. The mounting bolt (103) includes a M10 bolt passing through hole (107) in bottom block (101), through a hole (113) in the connecting block (102) and counter bored hole (115) on the top plate (105) connecting them as already explained above. In addition to these, the top plate (105) comprises of a forward/backward guideway (116) which ensures that gripper jaw assembly (100) moves as per the desired path. The locating block (106) has holes made with internal thread (118) to connect to the bottom plate (101) with draw bench (not shown). A half circle groove (117) is provided in the locating block (106) to seat in the turret head.

[0021] By the above way of connecting the components to form the gripper jaw assembly (100), in place of regular gripper jaw block has the following advantages:
- Reduction in material rejection rate by 20%;
- Reduction in cost incurred for jigs, fixture failure and replacement by 75%;
- Allows interchangeability between machine;
- Improvement in Production capacity by 40%.

TEST RESULT
[0022] The invention was successfully used in 50T Draw bench at Cold Mill/SSTP so as to grip the mother tube during drawing process without failure.

WORKING OF THE INVENTION
[0023] In Cold drawing process, the Draw benches have three components: a back bench, die head, and front section. The Die head is made of sintered tungsten carbide inserts with a cobalt binder that have been shrunk-fit into a steel casing. A plug made of Tungsten carbide or Die steel is threaded or brazed onto the end of a mandrel rod which is anchored at the back of the bench. The tube to be drawn is loaded over the mandrel rod. The gripper jaw assembly of the invention is mounted on a carriage/trolley (Front section) and is used for gripping the tube. A hook on the back of the trolley engages a moving chain, pulling the tube through the Die and plug.

[0024] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.

[0025] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

[0026] 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 particulars 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 recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogues 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”.

[0027] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.

[0029] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.

[0030] 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.

LIST OF THE COMPONENTS WITH REFERENCE NUMERALS

101 Bottom block
102 Connecting block
103 Mounting bolts
104 Cylindrical gripping block
105 Top plate
106 Locating block
107
Counter bore M10 hole in bottom plate
108
Counter bore screw hole in bottom plate
109
Projection in bottom block to seat the cylindrical gripping block

110
Recession in the cylindrical gripping block
111 Groove along the axis
112 Half radius threads
113
M10 thru holes in connecting Block
114 Step in Connecting block
115
Counter bore in top plate for connecting block
116
Forward/backward guideway on the top plate
117
Half radius groove on locating Block
118 Screw hole on the locating block
, Claims:WE CLAIM
1. A gripper jaw assembly used in the cold drawing process for manufacturing seamless tubes comprising of bottom block (101) mounted with connecting block (102), cylindrical gripping block (104), top plate (105), locating block (106) connected to the bottom plate (101) with draw bench, in which the gripping cylindrical block (104) is inserted into step (114) on inside surface of the connecting block (102).

2. The gripper jaw assembly as claimed in claim 1, wherein the connecting block (102) is mounted in the back side of the bottom block (101) by tightening it with multiple mounting bolts (103) with a plurality of equally spaced through bore holes (107).

3. The gripper jaw assembly as claimed in claim 1 or 2 comprising of holes with counter bore (108) perpendicular to the hole along one side for mounting the locating block (106).

4. The gripper jaw assembly as claimed in claims 1-3, wherein the bottom block (101) has a step projection (109) of a circle which is divided into two unequal parts by a chord at a particular distance from the centre, in which the other part of circle is part of the mating bottom half.

5. The gripper jaw assembly as claimed in claims 1-4, wherein the gripping cylindrical block (104) with half radius threads (112) perpendicular to the cylindrical axis is fitted with the connecting block (102) through a groove (111) in the gripping cylindrical block (104).

6. The gripper jaw assembly as claimed in claims 1-5, wherein the recession (110) in the bottom of gripping cylindrical block (104), along the axis makes the seating with step projection (109) on bottom block (101) that during the return stroke, the gripping cylindrical block (104) does not come out of the gripper jaw assembly (100) used in the forward stroke for drawing operation.

7. The gripper jaw assembly as claimed in claims 1-6, wherein the mounting bolt (103) passes through hole (107) in bottom block (101), through hole (113) in the connecting block (102) and counter bored hole (115) on the top plate (105) connecting therewith.

8. The gripper jaw assembly as claimed in claims 1-7, wherein the top plate (105) comprises of a forward/backward guideway (116) which ensures that gripper jaw assembly (100) moves as per the desired path.

9. The gripper jaw assembly as claimed in claims 1-8, wherein the locating block (106) has holes with internal thread (118) to connect to the bottom plate (101) with draw bench, in which a half circle groove (117) is provided in the locating block (106) to seat in the turret head.

10. The gripper jaw assembly as claimed in claims 1-9 comprising of Gripping pad, which is a cylindrical block secured in its place by a top, bottom plate and connecting block, in which the Gripping pad is an interchangeable part of the gripper jaw assembly which may be changed based on the tube material and outer diameter (OD).