Description:THIS APPLICATION IS A PATENT OF ADDITION TO INDIAN PATENT APPLICATION NO. 201621020178 FILED ON JUNE 13th, 2016.
FIELD
The present disclosure relates to field of superfinishing technology. Particularly to a field of super finishing operation on threads of a ball screw.
DEFINITION
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise.
BALL SCREW: The term ‘BALL SCREW’ used in the context of this disclosure refers to, but is not limited to, ball screw is a mechanical linear actuator that converts rotational motion into linear motion with minimal friction. the ball screw has a first end, a second end and a cylindrical body with a longitudinal helical raceway for balls.
SUPER-FINISHING: The term ‘SUPER FINISHING’ used in the context of this disclosure refers to, but is not limited to, a machining or a polishing process which improves the surface roughness to finer level roughness by removing only skin layer (1-10 microns), which also leads to improve the anti-friction condition, also cause of reducing the vibrations by some extend.
BACKGROUND
A ball screw is a mechanical linear actuator that converts rotational motion into linear motion with minimal friction. Conventionally, a ball screw includes a threaded shaft which provides a helical raceway for balls and functions as a precision screw. Ball screws are generally used in steering systems for automobiles and for motion transmission in machine tools.
During manufacturing, it is required that ball screws be machined with super finishing operations after heat treatment. Conventional methods of performing finishing operations on ball screws include manual/semi-automatic processes which are far from reliable because of the human intervention involved. An example of performing a finishing operation on ball screws includes polishing the ball screw manually using various abrasives, precision machining, grinding methods, and the like. However, when employing these conventional finishing methods, the ball screw is susceptible to deformation or bending caused by its own self weight and the forces generated during the machining process. As a result, the threads of the ball screw end up with an uneven surface finish, impeding its optimal performance. Further, to support the self-weight of the ball screw, in the conventional method of super finishing, a separate attachment is required which create hinderance in the machining of the ball screw.
Accordingly, there exists a need to provide an apparatus for performing super finishing operations on threads of a ball screw which overcomes the abovementioned drawbacks.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment 5 herein satisfies, are as follows:
An object of the present disclosure is to provide an apparatus for performing super finishing operation on threads of a ball screw.
Another object of the present disclosure is to provide an apparatus which supports the self-weight of the ball screw while machining.
Still another object of the present disclosure is to provide an apparatus which performs the finishing operation of the threads while supporting the ball screw.
Yet another object of the present disclosure is to provide an apparatus which is simple and economical.
Still another object of the present disclosure is to provide an apparatus which reduces the machine lead time.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisages an apparatus for performing super finishing operation on threads of a ball screw. The ball screw is defined by first end and second end and a cylindrical body provided with a longitudinal helical raceway for balls. The apparatus comprises at least one holder to removably hold either the first end or the second end of the ball screw; a first replaceable finishing tool which is configured with a threaded portion on an operative first inner concave portion; a second replaceable finishing tool which is configured with a threaded portion on an operative second inner concave portion, the first and the second inner concave portions are configured to operatively abut to form a hollow cylindrical cavity and further configured to clamp an operative cylindrical portion of the ball screw within the cavity; a slit film backed abrasive is configured to continuously fed within circumferential surface of the cavity to form an interface between the finishing tools and the operative cylindrical body portion containing threads of the ball screw; and at least one driving means which is configured to rotate and linearly displace the holder with the ball screw mounted thereon relative to the threaded portion of the inner concave portions. The ball screw mounted on the holder is configured to traverse through the cavity to perform the super-finishing operation of the ball screw.
In an embodiment, the first replaceable finishing tool and the second replaceable finishing tool is defined by a “C” shaped body.
In an embodiment, the apparatus includes a pair of arms. Each of the arm is configured to mount the first replaceable finishing tool and the second replaceable finishing tool, respectively. The arms are configured to be pivotally mounted on the apparatus to support the self-weight of the ball screw in an operative configuration of the apparatus.
In an embodiment, the pivot axis of the arms and the centroidal axis of the ball screw is parallel in an operative configuration of the apparatus. In an embodiment, the pivot axis of the arms and the centroidal axis of the ball screw is coplanar in an operative configuration of the apparatus. In an embodiment, the centroidal axis (C) is perpendicular to an axis (M) passing perpendicular from the pivot axis (P).
In an embodiment, the holder is configured to slide back and forth to move the ball screw through the cavity longitudinally for performing the finishing operation of the ball screw in an operative configuration of the apparatus.
In an embodiment, the slit film backed abrasive is a non-woven abrasive. The thickness of the slit film backed abrasive is in range of 0.2mm to 1.0mm.
In an embodiment, the threaded portion defined in the concave portions is configured to be complimentary to the thread of the ball screw. The slit film backed abrasive is provided with a pitch, which is equal is equal to pitch defined on the threaded section of the inner concave portions of the finishing tool and pitch defined on the thread of the ball screw.
In an embodiment, the apparatus includes a gear driven indexing mechanism. The indexing mechanism is configured to control the movement of the slit film backed abrasive between the inner concave portions of the finishing tools and the operative portion of the ball screw.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
An apparatus for performing super finishing operation on threads of a ball screw, of the present disclosure will now be described with the help of the accompanying drawing, in which:
Fig. 1A illustrates a schematic view of a conventional apparatus for performing finishing operation on a ball screw;
Fig. 2 illustrates isometric view of a finishing tool with the ball screw of the conventional apparatus for performing finishing operation on a ball screw;
Fig. 3 illustrates an isometric view of a finishing tool used in the conventional apparatus of Figure 1 and Figure 2;
Fig. 4 illustrates a schematic view of the present replaceable finishing tool of the present apparatus with the ball screw for performing super finishing operation on threads of a ball screw, in accordance with an embodiment of the present disclosure;
Fig. 5 illustrates a schematic view of the present replaceable finishing tool of the present apparatus mounted on a gripping means, in accordance with an embodiment of the present disclosure;
Fig.6 illustrates a schematic view of the slit film backed abrasive in respective concave portion of the replaceable finishing tool of the present apparatus, in accordance with an embodiment of the present disclosure;
Fig.7 illustrates a schematic arrangement of the slit film backed abrasive in respective concave portion of the replaceable finishing tool and the ball screw of the present apparatus, in accordance with an embodiment of the present disclosure;
Fig. 8 illustrate a schematic view of arms with the gripping means and an actuator, in accordance with an embodiment of the present disclosure; and
Fig. 9 illustrates an isometric view of at least one holder with the ball screw mounted therein, and the arms with the replaceable finishing tool, in accordance with an embodiment of the present disclosure.
LIST OF REFERENCE NUMERALS
100' Conventional Apparatus for performing super finishing operation
100 Apparatus of present disclosure for performing super finishing operation on threads of a ball screw
10 First replaceable Finishing tool
10A first concave portion of First replaceable Finishing tool
15 Second replaceable finishing tool
15A second concave portion of Second replaceable finishing tool
20 Slit film backed abrasive
30 Gripping means
40 Ball screw
40A Threads
42 Holder
44 Driving means
46 Arm
50 Actuator
P Pivot axis of arms
C Centroidal axis of ball screw
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises”, “comprising”, “including” and “having” are open-ended transitional phrases and therefore specify the presence of stated features, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, elements, components, and/or groups thereof.
When an element is referred to as being “mounted on”, “engaged to”, “connected to” or “coupled to” another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Terms such as “bottom”, “inner”, “outer”, “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
During manufacturing, it is required that ball screws be machined with super finishing operations after heat treatment. Conventional apparatus (100’)/ methods of performing finishing operations on ball screws (40) include manual/semi-automatic processes which are far from reliable because of the human intervention involved. An example of performing a finishing operation on ball screws includes polishing the ball screw manually using various abrasives, precision machining, grinding methods, and the like. Fig. 1A illustrates a schematic view of a conventional apparatus for performing finishing operation on a ball screw; Fig. 2 illustrates isometric view of a finishing tool with the ball screw of the conventional apparatus for performing finishing operation on a ball screw; and Fig. 3 illustrates an isometric view of a finishing tool used in the conventional apparatus of Figure 1 and Figure 2.
However, when employing these conventional finishing methods, the ball screw is susceptible to deformation or bending caused by its own self weight and the forces generated during the machining process. As a result, the threads of the ball screw end up with an uneven surface finish, impeding its optimal performance. Further, to support the self-weight of the ball screw, in the conventional method of super finishing, a separate attachment is required which create hinderance in the machining of the ball screw.
In order to address the aforementioned problems, the present disclosure envisages an apparatus (100) for performing super finishing operation on threads of a ball screw. The present disclosure is explained with reference to the figure 4 to figure 9. The ball screw (40) is defined by first end and second end and a cylindrical body with a longitudinal helical raceway thereon for balls. The apparatus (100) comprises at least one holder (42), a first replaceable finishing tool (10), a second replaceable finishing tool (15), a slit film backed abrasive (20) and at least one driving means (44). Fig. 4 illustrate a schematic view of the present replaceable finishing tool of the present apparatus with the ball screw for performing super finishing operation on threads of a ball screw, Fig. 5 illustrate a schematic view of the present replaceable finishing tool of the present apparatus mounted on a gripping means.
The holder (42) is configured to removably hold the extreme ends .i.e. the first end and the second end of the ball screw (40). The holder (42) is further configured to slide back and forth on a sliding bed (not shown) to enable the movement of the ball screw parallelly to the sliding bed. The movement of the ball screw over the bed enable the finishing operation of the ball screw to a desired length in an operative configuration of the apparatus (100).
Further, the apparatus (100) is provided with splitable arms. These arms are configured to split and separate as two independent arms (46) so as to hold and supports the operative cylindrical portion of the ball screw (40) while in operation. Each arm (46) is configured to be actuated by means of an actuator (50) and is further configured to attach at least one gripping means (30).
In an embodiment, each arm (46) splits in an operative vertical direction so as to optimize the space requirement and utilize the vertical space of the apparatus (100).
In an embodiment, the gripping means (30) is either slidably mounted or fastened to an operative extreme end of each of the arm (46).
In an embodiment, the arms (46) are configured to be pivotally mounted (P) on the apparatus (100) to thereby support the self-weight of the ball screw (40) in an operative configuration of the apparatus (100).
The gripping means (30) is defined with a cut-out to receive the finishing tools therein. The finishing tool is divided as the first replaceable finishing tool (10) and the second replaceable finishing tool (15). The first replaceable finishing tool (10) and the second replaceable finishing tool (15) is defined by a “C” shaped body structure with a first concave portion (10A) and a second concave portion (15A) therein. The first operative concave portion (10A) and the second operative concave portion (15A) of each of the replaceable finishing tools (10, 15) is configured with a threaded portion.
In an embodiment, the threaded portion provided on the concave portions (10A, 15A) of the first and second replaceable finishing tools (10, 15) is complementary to the threads of the ball screw. The first and the second inner concave portions (10A, 15A) of the first and the second replaceable finishing tools (10, 15) is configured to operatively abut to form a hollow cylindrical cavity and is further configured to clamp an operative cylindrical portion of the ball screw (40) within the cavity.
In an embodiment, the first and the second inner concave portions (10A, 15A) of the first replaceable finishing tool (10) and the second replaceable finishing tool (15) are configured to partially cover the operative cylindrical portion of the ball screw (40) in an operative configuration of the apparatus (100).
Since, during machining, the first replaceable finishing tool (10) and the second replaceable finishing tool (15) partially covers the operative cylindrical portion of the ball screw (40) and supports the ball screw. And, the pivot axis (P) of the arms and the centroidal axis (C) of the ball screw (40) is mutually parallel and coplanar in an operative configuration of the apparatus (100). Advantageously, thereby it avoids the possibility of the bulging of the ball screw (40) due to its self-weight or due to the force generation while machining.
In an embodiment, the centroidal axis (C) is perpendicular to an axis (M) passing perpendicular from the pivot axis (P).
The apparatus is configured with the slit film backed abrasives (20) and is further configured to be fed within a circumferential surface of the first and the second inner concave portions (10A, 15A) of the first finishing tool (10) and the second finishing tool (15). The slit film, thus forms an interface between the threaded portion provided on the concave portions (10A, 15A) of the replaceable finishing tools (10, 15) and the threads of the ball screw (40) during machining. The slit film is provided with a uniform pitch along width of slit film. The pitch defined on the slit film backed abrasive (20) is equal to pitch defined on the threaded section (or portion) of the inner concave portions (10A, 15A) of the finishing tools and pitch defined on the thread (40A) of the ball screw (40). Fig.6 illustrates a schematic view of the slit film backed abrasive in respective concave portion of the replaceable finishing tool of the present apparatus; and Fig.7 illustrates a schematic arrangement of the slit film backed abrasive in respective concave portion of the replaceable finishing tool and the ball screw of the present apparatus, in accordance with an embodiment of the present disclosure.
In an embodiment, the slit film backed abrasives is configured to be driven at the interface formed between the threaded portion of the replaceable finishing tools (10, 15) and the threads of the ball screw (40) by means of a gear driven indexing mechanism. The indexing mechanism is configured to control the movement of the slit film backed abrasive (20) between the first and the second inner concave portions (10A, 15A) of the finishing tools (10, 15) and the operative portion of the ball screw (40).
In an embodiment, the slit film backed abrasive (20) is a non-woven abrasive.
In an embodiment, the depth of the individual slit of the continuous slit film backed abrasive (20) is equal to difference between the major diameter and the minor diameter of the thread (40A) of the ball screw (40) in an operative configuration of the apparatus (100).
In an embodiment, the thickness of the slit film backed abrasive (20) is in range of 0.2mm to 1.0mm.Further, the apparatus (100) includes at least one driving means (44). The driving means (44) is configured to be coupled with the holder (42) and is further configured to rotate the holder (42) with the ball screw (40). The rotational motion of the holder (42) facilitates a linear displacement of the ball screw (40) relative to the threaded portion provided on the first and the second concave portions (10A, 15A) of the first and second replaceable finishing tools (10, 15) during machining, and thus the desired length of the ball screw gets machined. Fig. 8 illustrate a schematic view of arms with the gripping means and an actuator and Fig. 9 illustrates an isometric view of at least one holder with the ball screw mounted therein, and the arms with the replaceable finishing tool, in accordance with an embodiment of the present disclosure.
In an embodiment, the apparatus (100) can have only one driving means (44), which is configured to rotate the ball screw (40) as well as to move the slit film backed abrasive (20) in an operative configuration of the apparatus (100).
In another embodiment, the apparatus (100) can have two separate driving means (44), one is coupled with the holder (42) and the other is coupled with the slit film backed abrasive (20). The two-driving means (44) are configured to rotate at two different speed ratios.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
TECHNICAL ADVANCEMENTS AND ECONOMIC SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of the apparatus for performing super finishing operation on threads of a ball screw, that:
• supports the self-weight of the ball screw while machining and thus avoid the buckling of the ball screw during superfinishing operation;
• performs the finishing operation of the threads while supporting the ball screw;
• is simple and economical; and
• reduces the machine lead time.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
, Claims:WE CLAIM:
1. An apparatus (100) for performing super finishing operation on threads of a ball screw, the ball screw (40) defined by first end and second end and a cylindrical body having a longitudinal helical raceway for balls, said apparatus (100) comprising:
• at least one holder (42) to removably hold either the first end or the second end of the ball screw (40);
• a first replaceable finishing tool (10) configured with a threaded portion on an operative first inner concave portion (10A);
• a second replaceable finishing tool (15) configured with a threaded portion on an operative second inner concave portion (15A), said first inner concave portion (10A) and said second inner concave portion (15A) configured to operatively abut to form a hollow cylindrical cavity and further configured to clamp an operative cylindrical portion of the ball screw within said cavity;
• a slit film backed abrasive (20) configured to be continuously fed within circumferential surface of said cavity to form an interface between the threaded portion of said concave portions (10, 15) and the operative cylindrical portion containing threads of the ball screw (40); and
• at least one driving means (44) configured to be in communication with said holder and further configured to rotate and linearly displace the holder (42) with the ball screw mounted thereon relative to said threaded portion of said inner concave portions (10A, 15A),
wherein the ball screw mounted on said holder configured to traverse through said cavity to perform the super-finishing operation of the ball screw.
2. The apparatus (100) as claimed in claim 1, wherein said holder (42) is configured to slide back and forth to move the ball screw longitudinally for performing said finishing operation of the ball screw in an operative configuration of said apparatus (100).
3. The apparatus (100) as claimed in claim in 1, wherein said cavity formed by said inner concave portions (10A, 15A) is configured to partially cover said operative cylindrical portion of the ball screw (40) in an operative configuration of said apparatus (100).
4. The apparatus (100) as claimed in claim in 1, wherein said first replaceable finishing tool (10) and said second replaceable finishing tool (15) is defined by a “C” shaped body.
5. The apparatus (100) as claimed in claim 4, includes a pair of arms (46), each of said arm (46) is configured to mount said first replaceable finishing tool (10) and said second replaceable finishing tool (15) thereon respectively.
6. The apparatus (100) as claimed in claim 5, said arms (46) are configured to be pivotally mounted on said apparatus (100).
7. The apparatus (100) as claimed in claim 5, wherein pivot axis (P) of said arms and centroidal axis (C) of the ball screw (40) is parallel in an operative configuration of said apparatus (100).
8. The apparatus (100) as claimed in claim 5, wherein the centroidal axis (C) is perpendicular to an axis (M) passing perpendicular from the pivot axis (P).
9. The apparatus (100) as claimed in claim 5, wherein pivot axis (P) of said arms and the centroidal axis (C) of the ball screw (40) is coplanar in an operative configuration of said apparatus (100).
10. The apparatus (100) as claimed in claim in 5, wherein said first replaceable finishing tool (10) and said second replaceable finishing tool (15) are configured to be mounted on said arm (46) by means of a gripping means (30).
11. The apparatus (100) as claimed in claim 1, wherein said slit film backed abrasive (20) is a non-woven abrasive.
12. The apparatus (100) as claimed in claim 1, wherein said threaded portion defined in said concave portions (10A, 15A) are configured to be complimentary to the thread (40A) of the ball screw (40).
13. The apparatus (100) as claimed in claim 11, wherein said slit film backed abrasive (20) is provided with a pitch, which is equal to pitch defined on the threaded section of said inner concave portions (10A, 15A) of said finishing tool and pitch defined on the thread (40A) of the ball screw (40).
14. The apparatus (100) as claimed in claim 1, wherein depth of said individual slit of said continuous slit film backed abrasive (20) in said threaded portion of said finishing tools (10, 15) is equal to difference between the major diameter and the minor diameter of the thread (40A) of the ball screw (40) in an operative configuration of said apparatus (100).
15. The apparatus (100) as claimed in claim 1, wherein said apparatus (100) includes a gear driven indexing mechanism which is configured to control the movement of said slit film backed abrasive (20) between said inner concave portions (10A, 15A) of said finishing tools (10, 15) and the operative portion of the ball screw (40).
16. The apparatus (100) as claimed in claim 1, wherein the thickness of said slit film backed abrasive (20) is in range of 0.2mm to 1.0mm.

Dated this 21st day of July, 2023

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K. DEWAN & CO.
Authorized Agent of Applicant