FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10 and rule 13]
“A TEST FIXTURE FOR COIL SPRING AND A METHOD OF
ASSEMBLING THEREOF”
NAME AND ADDRESS OF THE APPLICANT:
TATA MOTORS LIMITED, an Indian company having its registered office at Bombay
house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra, INDIA.
Nationality: Indian
The following specification particularly describes the invention and the manner in which it is to be performed.
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TECHNICAL FIELD
This disclosure relates to a test fixture for a coil spring. More particularly this test fixture is used to measure the stiffness and the durability performance to evaluate the fatigue life of automotive suspension coil springs.
BACK GROUND OF THE INVENTION
A typical vehicle suspension is made up of two components that are a spring and a damper. The suspension stores energy in the spring and dissipates energy through the damper. Both components are fixed at the design stage. The spring is chosen based solely on the weight of the vehicle, while the damper is the component that defines the suspensions placement on the compromise curve. Hence design of the spring in the suspension design is very crucial.
It is required to measure the spring performance like stiffness & perform durability on the coil spring to evaluate life as per design requirements, in the vehicle suspension development cycle. Spring photograph & component drawing are shown in Figs. 1a & 1b.
Conventionally spring setup & test fixtures are shown in the Fig-2. The limitation of this set up & fixture is high set up time, change in the fixture design according to the different spring sizes, which is more unproductive and unsafe for the operation. To overcome this problem a novel test fixture is designed which can accommodate wide range of springs, which are used in vehicle suspension.
STATEMENT OF THE DISCLOSURE
Accordingly, the disclosure provides a test fixture for a coil spring comprising, a top mounting fixture and a bottom mounting fixture for supporting the coil spring, wherein at least one of the spring fixture is provided with at least two slots that slidabily accommodates at least one fastening element on each slot, at least one movable spring holder provided on each fastening element to hold the coil, and a stopper member provided between the top mounting fixture and the bottom mounting fixture, wherein the coil spring is placed around the stopper member, it also provides a method of assembling a test fixture for a coil spring said method comprising, mounting bottom end of a stopper member (9b) to a bottom mounting fixture, wherein the bottom mounting fixture is
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provided with at least two slots to slidably accommodate at least one fastening element on each slot, placing the coil spring around the stopper member, mounting a top mounting fixture with a stopper member (9a); wherein the top mounting fixture is provided with at least two slots to slidably accommodate at least one fastening element on each slot and clamping the coil spring to the fastening element using plurality of movable spring holder. Also, it provides a method of testing a coil spring, said method comprises acts of, mounting bottom end of a stopper member (9b) to a bottom mounting fixture, wherein the bottom mounting fixture is provided with at least two slots to slidably accommodate at least one fastening element on each slot, placing the coil spring around the stopper member, mounting a top mounting fixture with a stopper member (9a); wherein the top mounting fixture is provided with at least two slots to slidably accommodate at least one fastening element on each slot, clamping the coil spring to the fastening element on the spring fixtures using plurality of movable spring holders; and applying load on the coil spring in predetermined quantity through the test machine.
SUMMARY OF THE DISCLOSURE
The shortcomings of the prior art are overcome and additional advantages are provided through the provisions as described in disclosure.
Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
The disclosure provides a test fixture for a coil spring comprising, a top mounting fixture and a bottom mounting fixture for supporting the coil spring, wherein at least one of the spring fixture is provided with at least two slots that slidabily accommodates at least one fastening element on each slot. Further at least one movable spring holder is provided on each fastening element to hold the coil spring. And a stopper member is provided between the top mounting fixture and the bottom mounting fixture, wherein the coil spring is placed around the stopper member.
In one embodiment of the present disclosure the movable spring holder consists of a spring end clamp provided with plurality of semi-circular grooves to accommodate free end diameter of the coil spring.
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In one embodiment of the present disclosure the movable spring holder consists of a spring holding clamp that supports the coil spring on any one of the sides of the coil spring.
In one embodiment of the present disclosure the stopper member is plurality of tubes with different diameters.
In one embodiment of the present disclosure the tubes are arranged concentrically and mounted on said top and bottom fixtures respectively, such that one of the tube moves inside the other tube.
Another embodiment of the present disclosure provides a method of assembling a test fixture for a coil spring said method comprising, mounting bottom end of a stopper member (9b) to a bottom mounting fixture, wherein the bottom mounting fixture is provided with at least two slots to slidably accommodate at least one fastening element on each slot. Further, placing the coil spring around the stopper member. And mounting a top mounting fixture with a stopper member (9a); wherein the top mounting fixture is provided with at least two slots to slidably accommodate at least one fastening element on each slot and clamping the coil spring to the fastening element using plurality of movable spring holder.
Another embodiment of the present disclosure provides a method of testing a coil spring, said method comprises acts of, mounting bottom end of a stopper member (9b) to a bottom mounting fixture, wherein the bottom mounting fixture is provided with at least two slots to slidably accommodate at least one fastening element on each slot, placing the coil spring around the stopper member, mounting a top mounting fixture with a stopper member (9a); wherein the top mounting fixture is provided with at least two slots to slidably accommodate at least one fastening element on each slot, clamping the coil spring to the fastening element on the spring fixtures using plurality of movable spring holders; and applying load on the coil spring in predetermined quantity through the test machine.
In an alternative embodiment of the present disclosure the stopper is selected from a group comprising solid metallic element and elastic element, which arrests the movement of the spring during testing of coil spring.
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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
The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:
Fig 1 illustrates the schematic diagram of a coil spring having different diameters.
Fig 2, illustrates a photographic image of conventional test fixture.
Figs. 3a, 3b and 3c illustrate the front view, side view, and top view of the test fixture according to the disclosure.
Figs. 4a, 4b, 4c and 4d illustrate the front view, left profile view, top view and perspective view of the spring end clamp according to the disclosure.
Figs. 5a, 5b and 5c the front view, top view and perspective view of the spring holding clamp according to the disclosure.
Fig 6 shows the schematic representation of the coil spring mounted on a test rig.
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.
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DETAIL DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
It is to be noted at this point that all of the above described components, whether alone or in any combination, are claimed as being essential to the disclosure, in particular the details depicted in the drawings and reference numerals in the drawings are as given below.

Referral Numerals Description
1 Coil spring
2 Top mounting fixture
3 Bottom mounting fixture
4 Fastening element
4a bolts
4b Nuts
5 Load cell mounting stud
6 Actuator mounting stud
7 Spring end clamp
7a, 7b, 7c Semi-circular grooves
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8 Spring holding clamp
9a, 9b First tube and second tube
10 slot
11 Vertical column
12 Cross Head
13 Load cell
14 Hydraulic Actuator
15 Actuator Base
16 Testing machine
This present disclosure disclosed herein relates a test fixture for a coil spring (1) accommodating different wire diameters. More particularly this test fixture is used to measure the stiffness and the durability performance to evaluate the fatigue life of a suspension coil spring.
The disclosure provided herein discloses a test fixture for measuring the coil spring characteristics as shown schematically in figs. 3a, 3b & 3c. The test fixture is provided with a bottom mounting fixture (3) at its bottom which is fixed to an actuator with the help of actuator mounting stud (6). The test fixture on the top most part is provided with a top mounting fixture (2) which is fixed to load cell with the help of load cell mounting stud (5). Also, the schematic fig. 3c, illustrates the top and bottom fixture provided with at least two slots (10) to slidabily accommodate at least one fastening element (4) on each slot (10). Wherein the bottom fixture is not visible in the top view. The fastening element (4) used in these fixtures (2, 3) are standard M16 bolts (4a) and nuts (4b). Each bolt (4a) in the said fixture is provided with a M16 nut (4b) to lock the position of the fastening element (4). Before assembling the spring (1) to the test rig, a stopper member is assembled to the test rig. The stopper member consists of a second tube (9b) which is assembled with the actuator mounting stud (6) at bottom and a first tube (9a) assembled to load cell mounting stud (5). These tubes acts as guide as shown in the figure - 3. The diameter of the tubes (9a) and (9b) are different. These tubes are arranged in such a manner that one tube fits concentrically into the other tube during the testing of coil spring. The purpose of these tubes (9a and 9b) is to avoid displacement of the spring accidentally, during the test. Thus these tubes (9a and 9b) ensure safe operation. In an alternative embodiment the stopper member can be a metallic solid element or an
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elastic member which serves the purpose of arresting the coil spring to be displaced from the test rig in case of any accidents while testing. It should be appreciated that these embodiment are described for purpose of illustration only, and that numerous other alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. Further the coil spring (1) is clamped to the test fixture using plurality of movable spring holders. The movable spring holder consists of a spring end clamp (7) and a spring holding clamp (8).
The detail schematic of a spring end clamp (7) is shown in fig. 4a, 4b, 4c & 4d. The spring end clamp (7) is provided with M16 standard threads which engages with M16 bolts (4a) provided in the slots (10) of the test fixture. And said spring end clamp (7) is provided with plurality of semi-circular grooves (7a, 7b, 7c) on its body. The purpose of these grooves is to hold the wire diameter of the coil spring (1). Each semi-circular groove is of different diameter as shown in fig. 4a, 4b, 4c and 4d. Once the wire diameter is fixed in the semi-circular groove the spring end clamp (7) is locked. And the fastening element (4) is fixed to its position with the help of the M16 nut (4b).
The detail schematic of a spring holding clamp (8) is shown in fig. 5a, 5b & 5c. The spring holding clamp (8) having M16 standard thread is provided on the fastening element (4) which will engage with the M16 threaded fastening element (4). The coil spring (1) is held in its position by rotating the holding clamp (8) manually as per the spring helix angle or as per slope diagram of the spring or till the holding clamp touches to the spring. As soon as spring holding clamp (8) makes contact with the spring (1) the M16 nut (4b) provided on the fastening element (4) is tightened to hold the spring holding clamp (8) at the desired position. The detail schematic of spring holding clamp (8) is shown in fig. 5.
When the diameters of the coil spring (1) varies as shown in fig. 1, the test fixture is adjusted to the required coil spring (1) diameter by sliding the fastening element (4) in the slots (10) to adjust the top and bottom diameter of the spring (1). If only top diameter of the coil spring changes, the fastening element (4) provided in the top mounting fixture (2) is slided to the required position and is locked in the desired position by the nut (4b) provided on the fastening element (4). Also, if only bottom diameter of the coil spring (1) is changed, the fastening element (4) provided in the bottom mounting fixture (3) are
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slided to the required position and is locked in the desired position by the nut (4b) provided on the fastening element (4).
Once the fastening elements are adjusted and fixed, the spring end clamp (7) is inserted on either one of the fastening element (4) of the bottom mounting fixture (3), and the spring holding clamp (8) is provided on the other fastening element (4) of the bottom mounting fixture (3). Further same, spring end clamp (7) and spring holding clamp (8) inserts are provided for both the fastening element (4) in top mounting fixture (2). These test fixtures are made up of high strength & toughened steel so that they can withstand high shock loads during the durability tests.
The detailed schematic arrangement of spring (1) on rig is shown in the fig – 6. A load cell mounting stud is fixed to a load cell (13). And the load cell is mounted on a crosshead (12). The crosshead (12) is further mounted on a vertical column (11). The actuator mounting stud is fixed on the hydraulic actuator (14). Actuator is rigidly mounted on base (15). The cross head (12) height is adjusted as per spring length or as required. In this manner, the test fixture can be assembled for measuring the spring characteristics.
Thus the present disclosure is constructed to integrate functionalities of the measuring and testing of the coil spring (1) with respect to performance characteristic, durability and reliability in a single set up and facilitate ease of handling, fitment & safe operating practices. This testing arrangement further enables to produce accurate & consistent test results on different sizes of coil spring.
In an alternative embodiment, an angled form of holder can be provided to support the coil spring. The fastening element (4) in the spring mounting fixture is provided with an angled form of holder which arrests the movement of the spring i.e. the angled holder holds the coil spring in its position. A person skilled in art can infer that any shaped holder can serve the purpose of holding the coil spring in the disclosed invention.
The foregoing description provides specific embodiments of the present disclosure. It should be appreciated that these embodiment are described for purpose of illustration only, and that numerous other alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It
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is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.
Equivalents
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 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
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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.
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We claim:
1. A test fixture for a coil spring (1) comprising:
a top mounting fixture (2) and a bottom mounting fixture (3) for supporting the coil spring (1); wherein at least one of the spring fixture is provided with at least two slots (10) that slidabily accommodates at least one fastening element (4) on each slot (10);
at least one movable spring holder provided on each fastening element (4) to hold the coil spring (1); and
a stopper member provided between the top mounting fixture (2) and the bottom mounting fixture (3); wherein the coil spring (1) is placed around the stopper member.
2. The movable spring holder as claimed in claim 1, wherein the movable spring holder consists of a spring end clamp (7) provided with plurality of semi-circular groove (11a, 11b and 11c) to accommodate free end diameter of the coil spring (1).
3. The movable spring holder as claimed in claim 1, wherein the movable spring holder consists of a spring holding clamp (8) that supports the coil spring (1) on any one of the sides of the coil spring (1).
4. The test fixture as claimed in claim 1, wherein the stopper member is plurality of tubes (9a and 9b) with different diameters.
5. The stopper member as claimed in claim 4, wherein the tubes 9a, 9b are arranged concentrically and mounted on said top and bottom mounting fixture (2,3) respectively, such that one of the tube moves inside the other tube.
6. A method of assembling a test fixture for a coil spring (1) said method comprising:
mounting bottom end of a stopper member (9b) to a bottom mounting fixture (3); wherein the bottom mounting fixture (3) is provided with at least two slots (10) to slidably accommodate at least one fastening element (4) on each slot (10);
placing the coil spring (1) around the stopper member;
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mounting a top mounting fixture (2) with a stopper member (9a); wherein the top mounting fixture (2) is provided with at least two slots (10) to slidably accommodate at least one fastening element (4) on each slot (10); and
clamping the coil spring (1) to the fastening element (4) using plurality of movable spring holders.
7. A method of testing a coil spring, said method comprises acts of:
mounting bottom end of a stopper member 9b to a bottom mounting fixture (3);wherein the bottom mounting fixture (3) is provided with at least two slots (10) to slidably accommodate at least one fastening element (4) on each slot;
placing the coil spring (1) around the stopper member;
mounting a top mounting fixture (2) with a stopper member 9a; wherein the top mounting fixture (2) is provided with at least two slots (10) to slidably accommodate at least one fastening element (4) on each slot;
clamping the coil spring (1) to the fastening element (4) on the spring fixtures using plurality of movable spring holders; and
applying load on the coil spring (1) in predetermined quantity through a test machine.
Dated this 22nd Day of February, 2012
NAVEEN C.
Of K & S Partners
Agent for the Applicant
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A TEST FIXTURE FOR COIL SPRING AND A METHOD OF
ASSEMBLING THEREOF
ABSTRACT
The disclosure relates to a test fixture for a coil spring (1) comprising, a top mounting fixture (2) and a bottom mounting fixture (3) for supporting the coil spring (1), wherein at least one of the spring fixture is provided with at least two slots that slidabily accommodates at least one fastening element (4) on each slot. And at least one movable spring holder provided on each fastening element (4) to hold the coil spring (1) and a stopper member is provided between the top mounting fixture (2) and the bottom mounting fixture (3), wherein the coil spring (1) is placed around the stopper member.
Fig. 3
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