Claims:We claim:

1. An expansion fixture for outer diameter turning of a thin walled cylinder (104), the expansion fixture comprising:
a base plate (302) having sliding pins (306) threaded on its top surface;
a plurality of sliding blocks (304) forming a circular block assembly, each of the plurality of sliding blocks (304) is having a sliding slot (304-S), a clamping slot (304-C), and a central taper bore (304-TP), wherein each of the plurality of sliding blocks (304) is mounted on the top surface of the base plate (302) in such a way that the sliding slot (304-S) matches with respective sliding pin (306) threaded on the base plate (302);
a drive bolt (308) within a taper pin (310) fastened on the top surface of the base plate (302) through the central taper bore (304-TP) formed on each of the plurality of sliding blocks (306); and
a clamping fastener (312) fastened on the top surface of the base plate (302) through the clamping slot (304-C) formed on each of the plurality of sliding blocks (304).

2. The expansion fixture as claimed in claim 1, further comprising a push pin assembly (314) to slide respective sliding blocks (304) towards a central region of the circular block assembly for loading and unloading of the thin walled cylinder (104) over outer periphery of the plurality of sliding blocks (304) so as to perform the diameter turning of the thin walled cylinder (104).

3. The expansion fixture as claimed in claim 1, wherein the base plate (302) is mounted from its bottom surface on a lathe face plate.

4. The expansion fixture as claimed in claim 1, wherein the drive bolt (308) is formed with one of a hexagonal head or Allen head and with a fine pitch threading on a bottom end to match with a center threaded hole of the base plate (302).

5. The expansion fixture as claimed of claim 1, wherein the plurality of sliding blocks (304) are made of low-density metals.

6. The expansion fixture as claimed in the claim 1, wherein the plurality of sliding blocks (304) includes either 3 or 6 equal sliding blocks.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates, in general, to mechanisms for outer diameter turning of thin walled cylinders. This present disclosure, in particular, relates to a split-type expansion fixture for outer diameter turning of thin walled cylinders.
BACKGROUND
[0002] Background description includes information that may be useful in understanding the present subject matter. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed subject matter, or that any publication specifically or implicitly referenced is prior art.
[0003] Thin walled cylinders has a wall thickness of less than 7% of their inner diameter. Such thin walled cylinders are generally used as boiler shells, pressure tanks, pipes and in other low-pressure processing equipment. However, before implementation of these thin walled cylinders, outer diameter turning of these thin walled cylinders is required.
[0004] As shown in FIG. 1A, and 2A for outer diameter turning using a tool 102, the thin walled cylinders 104 are clamped in lathes using conventional axial and radial clamps 106. The axial and radial clamps 106 may include three jaw chuck, clamping pad, or studs. The conventional axial and radial clamps are generally not designed to completely enclose an inner circumference of the thin walled cylinder 104, which will result in deformation of the component due to clamping force (shown with arrows 108) and cutting force (shown with arrow 110) of the tool 102. A typical deformation 112 of the thin walled cylinder 104 during machining in the lathes using the conventional radial or axial clamps 106 is illustrated in FIGS. 1B and 2B. The deformation 112 of the thin walled cylinder 104 will affect the dimensional accuracy, shape, and surface finish of the thin walled cylinder 104. To overcome the mentioned issue related to the deformation 112, it is necessary to have a fixture which should provide required clamping force, but at the same time that fixture should also protect the thin walled cylinder 104 from the deformation 112 occurred due to the clamping force and the cutting force during machining of the thin walled cylinder 104.
[0005] Therefore, there is a need for a device or structure for outer diameter turning of the thin walled cylinders with stepped inner profile.
OBJECTS OF THE DISCLOSURE
[0006] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed hereinbelow.
[0007] An object of the present disclosure is to provide a split type expansion fixture for outer diameter turning of thin walled cylinder.
[0008] Another object of the present disclosure is to provide a split type expansion fixture in which thin walled cylinders can be machined with more dimensional accuracy, shape and surface finish, without any deformation.
SUMMARY
[0009] This summary is provided to introduce concepts related to split type expansion fixture for outer diameter turning of thin walled cylinders with plain or stepped inner profile. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0010] The present disclosure relates to an expansion fixture for outer diameter turning of a thin walled cylinder. The expansion fixture includes a base plate having sliding pins threaded on its top surface; a plurality of sliding blocks forming a circular block assembly, each of the plurality of sliding blocks is having a sliding slot, a clamping slot, and a central taper bore, wherein each of the plurality of sliding blocks is mounted on the top surface of the base plate in such a way that the sliding slot matches with respective sliding pin threaded on the base plate; a drive bolt within a taper pin fastened on the top surface of the base plate through the central taper bore formed on each of the plurality of sliding blocks; and a clamping fastener fastened on the top surface of the base plate through the clamping slot formed on each of the plurality of sliding blocks.
[0011] In an aspect, the expansion fixture further includes a push pin assembly to slide respective sliding blocks towards a central region of the circular block assembly for loading and unloading of the thin walled cylinder over outer periphery of the plurality of sliding blocks so as to perform the diameter turning of the thin walled cylinder.
[0012] In an aspect, the base plate is mounted from its bottom surface on a lathe face plate.
[0013] In an aspect, the drive bolt is formed with one of a hexagonal head or Allen head and with a fine pitch threading on a bottom end to match with a center threaded hole of the base plate.
[0014] In an aspect, the plurality of sliding blocks are made of low-density metals.
[0015] In an aspect, the plurality of sliding blocks includes either 3 or 6 equal sliding blocks.

BRIEF DESCRIPTION OF THE 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 methods that are consistent with the subject matter as claimed herein, wherein:
[0017] FIGS. 1A and 2A illustrate a conventional arrangement of outer diameter turning of a thin walled cylinder using conventional radial and axial clamps;
[0018] FIGS. 1B and 2B illustrate possible deformation occurred due to the clamping force applied by the conventional radial and axial clamps of the convention arrangement of outer diameter turning of the thin walled cylinder;
[0019] FIGS. 3A and 3B illustrate different views of a split type expansion fixture in un-assembled condition, in accordance with an embodiment of the present disclosure; and
[0020] FIGS. 4A and 4B illustrate different views of a split type expansion fixture in assembled condition, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION
[0021] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0022] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0024] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0025] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0026] Embodiments explained herein pertain to the manufacturing process and working principle of the Split type expansion fixture for outer diameter turning of thin walled cylinder, in which the thin walled cylinders outer diameter can be turned in lathes with more dimensional accuracy, shape and surface finish without any deformation.
[0027] Regardless of their specific construction, FIGS. 3-4 show an expansion fixture for diameter turning of the thin walled cylinder 104, in accordance with an exemplary implementation of the present disclosure.
[0028] Referring to FIGS. 3A, 3B, 4A and 4B, FIGS. 3A and 4A show top view of the expansion fixture, while FIG. 3B shows a cross-section A-A of the expansion fixture before assembly and FIG. 4B shows the cross-section A-A of the expansion fixture after assembly.
[0029] The expansion fixture is formed with a base plate 302 having a bottom surface and a top surface. The base plate 302 is mounted from its bottom surface on a lathe face plate (not shown in figures). On the top surface of the base plate 302, a number of threaded grooves are formed to mount a plurality of sliding blocks 304 forming a circular block assembly. In an aspect, the plurality of sliding blocks 304 includes 3 or 6 number of equal sliding blocks depending on the inner diameter of the thin walled cylinder 104 and required clamping force.
[0030] First, sliding pins 306 are threaded on the top surface of the base plate 302. The number of sliding pins 306 threaded on the base plate 302 corresponds to the number of sliding blocks 304 that would be mounted on the base plate 302. For instance, as shown in FIGS. 3A and 4A, there are six number of sliding pins 306 threaded for mounting of three number of slicking blocks 304. Although the nomenclature of “sliding pin” is used, those skilled in the art can appreciate that this nomenclature is only to distinguish or classify the pin and not on the basis of its functionality.
[0031] In an aspect, each of the plurality of sliding blocks 304 is having a sliding slot 304-S, a clamping slot 304-C, and a taper bore 304-TP on its center. With such configuration, each of the plurality of sliding blocks 304 is mounted on the top surface of the base plate 302 in such a way that the sliding slot 304-S matches with respective sliding pin 306 threaded on the base plate 302. The sliding pin 306 fitted on the base plate 302 will provide controlled movement of the sliding blocks 304 over the base plate 302.
[0032] Once the blocks 304 are mounted on the base plate 302 using the matching of the sliding slot 304-S and the respective sliding pin 306, a drive bolt 308 along with a 1:10 taper pin 310 is fastened on the top surface of the base plate 302 through the taper bore 304-TP formed on each of the plurality of sliding blocks 304. Such combination of the drive bolt 308 within the taper pin 310 will provide uniform pressure with fine movement on all the sliding blocks 304 for expansion, which will ensure required clamping pressure on the thin walled cylinder 104.
[0033] After obtaining required clamping pressure, the clamping screws 312 firmly fasten the sliding blocks 304 with the clamping slots 304-C formed on the base plate 302, so as to avoid any movement during machining of the thin walled cylinder 104. Since the sliding blocks 304 are completely enclosing the inner circumference of the thin walled cylinder 104 during its loading, the sliding blocks 304 will protect the thin walled cylinder 104 from the deformation which could occur due to the clamping force and the cutting force of the tool 102.
[0034] The expansion fixture further includes a push pin assembly 314 to slide respective sliding blocks 304 towards a central region of the circular block assembly for loading of the thin walled cylinder 104 over outer periphery of the plurality of sliding blocks 304 so as to perform outer diameter turning of the thin walled cylinder 104.
[0035] Further, in an aspect, in order to reduce the tightening torque on the drive bolt 108, the sliding blocks 304 can be made of aluminium or any other low-density metals.
MANUFACTURING PROCESS
[0036] In an exemplary implementation, the entire manufacturing process of the split type expansion fixture proposed herein can be summarized in following steps:
Base Plate 302: The base plate 302 is prepared with face machining on both side, followed with mark, drill and tapping of the holes/groves for the fastening of the clamping screws 312, the sliding pins 306 and the drive bolt 308.
Sliding Pin 306: The sliding pins 306 are threaded and fix on the front surface of the base plate 302, so as to control the movement/sliding of the sliding blocks 304 over the base plate 302.
Sliding blocks 304: A sliding block 304 is prepared in aluminium or any low density metals, from a circular plate with an outer diameter having machining allowance of 3-5 mm over the inner diameter of the thin walled cylinder 104. Each of the sliding blocks 304 is prepared by:
i. face machining the circular plate on both side to suit the height of the thin walled cylinder 104,
ii. carrying out the slotting operation on circular plate for the clamping screws 312 and the sliding pins 306,
iii. performing drilling and 1:10 taper boring on center of the circular plate equal to the diameter of the taper pin 310,
iv. slitting the circular plate in to 3 or 6 equal number of pieces which forms sliding block 304 and fixing them of the top surface of the base plate 302 while matching the slots on the threaded sliding pins 306,
v. using the taper pin 310 and drive bolt 308 to partly expand the sliding blocks 304,
vi. machining the outer diameter of the sliding blocks 304 to match the inner profile of the thin walled cylinder 104.
Push pin assembly 314: The push pin assembly 314 is prepared to push the sliding blocks 304 towards center for easy loading and unloading of the thin walled cylinder 104 after removal of taper pin 310.
Taper pin 310: The 1:10 taper pin 310 is prepared with outer diameter matching with the center taper bore 304-TP of each of the sliding blocks 304 before slitting. Then, the taper pin 310 is drilled to form a center through hole on the taper pin 310 to receive the drive bolt 308.
Drive Bolt 308: The drive bolt 3018 is prepared with hexagonal or Allen head, so as to turn the body diameter to have sliding fit with the taper pin 310 inner diameter and do fine pitch threading on the bottom end to match with center threaded hole formed on the base plate 302.
Clamping screw 312: The clamping screw 312 is prepared to fasten the sliding blocks 304 with the base plate 302 after obtaining the required clamping force through taper pin 310 and the drive bolt 308.
WORKGING OPERATION
[0037] Once the split type expansion fixture proposed herein has been manufactured, the following working operation shall be performed by the proposed split type expansion fixture for outer diameter turning of a thin walled cylinder 104:
[0038] In step 1, the base plate 302 is fixed on a lathe face plate or table.
[0039] In step 2, the sliding pins 306 threaded on the front surface of the base plate 302.
[0040] In step 3, the sliding blocks 304 are mounted on the front surface of the base plate 302 so as to ensure that the orientation of the sliding pin slots 304-S formed on the sliding blocks 304 matches with the sliding pin 306 threaded on the base plate 302.
[0041] In step 4, the clamping screws 312 are fastened, without full tightening, with the sliding block 304 and base plate 302.
[0042] In step 5, the push pin assembly 314 is used to push the sliding blocks 304 towards the center of the formed circular block assembly so as to load the thin walled cylinder 104.
[0043] In step 6, after loading of the thin walled cylinder 104 onto the sliding blocks 304, the taper pin 310 is placed through the center taper pin hole 304-TP formed on the sliding blocks 304.
[0044] In step 7, the drive bolt 308 is fastened with the base plate 302 through center through hole of the taper pin 310 to expand the sliding blocks 304 so as to obtain the required clamping pressure on the thin walled cylinder 104.
[0045] In step 8, after obtaining the required clamping pressure to machine the thin walled cylinder 104, the clamping screws 312 are full tightened.
[0046] In step 9, the expansion fixture is ready for outer diameter machining of the thin walled cylinder 104.
[0047] In step 10, after completion of outer diameter machining, the drive bolt 308 and the taper pin 310 are removed from the expansion fixture.
[0048] In step 11, the push pin assembly 314 is used to push the sliding blocks 304 towards the center of the circular block assembly so as to unload the machined thin walled cylinder 104.
[0049] It can be appreciated by those skilled in the art that all the components or elements of the device/machine proposed herein have been hardened before utilizing of the same.
[0050] Further, it will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope.
[0051] Furthermore, all examples recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.
[0052] The above description does not provide specific details of the 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.
[0053] 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.
[0054] 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.
[0055] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.