Claims:We claim,
1. A backlash prevention system (100) for achieving an anti-backlash movement of a structure (102), the backlash prevention system (100) comprising:
a first assembly (104) comprising:
a screw rod (202) to which the structure (102) is connected, wherein rotation of the screw rod (202) results in movement of the structure (102) along a first axis (106); and
an anti-backlash spring loaded nut (204) received by the screw rod (202), and connected to the structure (102), wherein the anti-backlash spring loaded nut (204) limits backlash movement while moving the structure (102) along the first axis (106); and
a second assembly (108) comprising a rack and pinion setup (302) to which the structure (102) is connected, wherein,
rotation of the pinion (304) results in movement of the structure (102) along the first axis (106);
the pinion (304) is an anti-backlash gear; and
operation of the first assembly (104) to move the structure (102) along the first axis (106) results in movement of the second assembly (108) along the first axis (106).
2. The backlash prevention system (100) as claimed in claim 1, wherein the structure (102) is a printhead of an additive manufacturing machine.
3. The backlash prevention system (100) as claimed in claim 2, wherein the first axis (106) is perpendicular to a print plate of the additive manufacturing machine.
4. The backlash prevention system (100) as claimed in claim 1, wherein the second assembly (108) further comprises a slider assembly (306), which enables the structure (102) to slide along the first axis (106) when the pinion (304) rotates to move the structure (102) along the first axis (106).
5. The backlash prevention system (100) as claimed in claim 4, wherein the slider assembly (306) comprises a track (308) and a slider (310), wherein one of the track (308) or the slider (310) is connected to the structure (102), such that the structure (102) is stationary relative to the connected track (308) or the slider (310).
6. The backlash prevention system (100) as claimed in claim 5, further comprising a structure holder (312), wherein the structure holder (312) is connected to the structure (102) such that:
the rack and pinion setup (302) is connected to the structure holder (312); and
one of the track (308) or the slider (310) of the slider assembly (306) is connected to the structure holder (312), such that the structure holder (312) is stationary relative to the connected track (308) or the slider (310).
7. The backlash prevention system (100) as claimed in claim 4, wherein the slider assembly (306) is a dovetail slider.
8. The backlash prevention system (100) as claimed in claim 1, further comprising a lateral frame (110) connecting the structure (102) to the first assembly (104), wherein rotation of the screw rod (202) results in movement of the lateral frame (110) along the first axis (106), thereby resulting in the movement of the structure (102) along the first axis (106).
9. The backlash prevention system (100) as claimed in claim 8, comprises a pair of first assemblies (104), wherein the lateral frame (110) extends between the pair of first assemblies (104).
10. The backlash prevention system (100) as claimed in claim 8, wherein second assembly (108) is engaged to the lateral frame (110).
11. The backlash prevention system (100) as claimed in claim 8, further comprising a housing (112), wherein the housing (112) supports the structure (102) and is connected to the lateral frame (110).
12. The backlash prevention system (100) as claimed in claim 1, wherein the movement of the structure (102) resulting from the rotation of the screw rod (202) is independent of the movement of the structure (102) resulting from the rotation of the pinion (304).
13. The backlash prevention system (100) as claimed in claim 1, wherein,
the screw rod (202) enables maximum movement of the structure (102) by a first distance;
the rack and pinion setup (302) enables maximum movement of the structure (102) by a second distance; and
the first distance is greater than the second distance.
14. The backlash prevention system (100) as claimed in claim 1, wherein the second assembly (108) is configured to extend or retract the structure (102) along the first axis (106) within a housing (112).
15. The backlash prevention system (100) as claimed in claim 1, comprises a pair of second assemblies (108) wherein,
each of the second assemblies (108) is connected to a separate structure (102); and
each of second assemblies (108) is independently operable to move the structure (102) along the first axis (106).
16. The backlash prevention system (100) as claimed in claim 15, further comprising a pair of motors (314), wherein shaft of each motor (314) is connected to the pinion (304) of each rack and pinion setup (302), wherein operation of the motor (314) results in rotation of the pinion (304), thereby resulting in movement of the structure (102) along the first axis (106).
17. The backlash prevention system (100) as claimed in claim 16, wherein the pair of motors (314) are connected to a housing (112), wherein the housing (112) supports the structure (102).
18. The backlash prevention system (100) as claimed in claim 1, wherein the first assembly (104) further comprises a sliding member (206), which enables the structure (102) to slide along the first axis (106) when the screw rod (202) rotates to move the structure (102) along the first axis (106).
19. The backlash prevention system (100) as claimed in claim 18, wherein the sliding member (206) comprises a slider guide (208) and a sliding block (210), wherein one of the slider guide (208) or the sliding block (210) is connected to the structure (102), such that the structure (102) is stationary relative to the connected slider guide (208) or the sliding block (210).
20. The backlash prevention system (100) as claimed in claim 19, further comprising:
a structure holder (312), wherein the structure holder (312) is connected to the structure (102); and
a lateral frame (110), wherein the lateral frame (110) is engaged to the structure holder (312), wherein one of the slider guide (208) or the sliding block (210) of the sliding member (206) is connected to the lateral frame (110), such that the lateral frame (110) is stationary relative to the connected slider guide (208) or the sliding block (210).
21. The backlash prevention system (100) as claimed in claim 18, wherein the sliding member (206) is a dovetail slider.

Dated this 17th day of January 2019
(Digitally signed)
Kartik PUTTAIAH
Patent Agent-IN/PA-1809
, Description:[0001] Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to being prior art by inclusion in this section.
Field of the invention:
[0002] The subject matter in general relates to backlash reduction in the movement of a structure. More particularly, but not exclusively, the subject matter relates to reducing backlash in the movement of a structure, wherein the movement of the structure is facilitated using screw rods and rack and pinion setup.
Discussion of the related field:
[0003] Backlash, sometimes also called as lash or play, is a clearance or lost motion in a mechanism caused by gaps between the parts. It can be defined as the maximum distance or angle through which any part of a mechanical system is moved in one direction without applying appreciable force or motion to the next part in mechanical sequence.
[0004] Backlash is also said to be present when a system fails to return to its exact starting position if its motion is reversed. Backlash also leads to unwanted motion leading to vibration, noise and diminished performance in machines.
[0005] In view of the foregoing discussion, there is a need for an improved technique for reducing backlash in machines.
SUMMARY
[0006] An embodiment provides a backlash prevention system for achieving an anti-backlash movement of a structure. The backlash prevention system comprises a first assembly and a second assembly. The first assembly comprises a screw rod to which the structure is connected, and an anti-backlash spring loaded nut. Rotation of the screw rod results in movement of the structure along a first axis. The anti-backlash spring loaded nut is received by the screw rod and is connected to the structure. The anti-backlash spring loaded nut limits backlash movement while moving the structure along the first axis. The second assembly comprises a rack and pinion setup to which the structure is connected, wherein the pinion is an anti-backlash gear. Rotation of the pinion results in movement of the structure along the first axis. Operation of the first assembly to move the structure along the first axis results in movement of the second assembly along the first axis.
BRIEF DESCRIPTION OF DRAWINGS
[0007] Embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:
[0008] FIG. 1 is an isometric view of a backlash prevention system 100, in accordance with an embodiment;
[0009] FIG. 2 is an isometric back view of the backlash prevention system 100 depicting a first assembly 104, in accordance with an embodiment;
[0010] FIG. 3A is an isometric view of a second assembly 108 of the backlash prevention system 100, in accordance with an embodiment;
[0011] FIG. 3B is an exploded view of the second assembly 108, in accordance with an embodiment;
[0012] FIG. 3C is an orthographic projection of the backlash prevention system 100, in accordance with an embodiment;
[0013] FIGs. 4A and 4B illustrate the working of the first assembly 104, in accordance with an embodiment; and
[0014] FIGs. 5A and 5B illustrate the working of the second assembly 108, in accordance with an embodiment.
DETAILED DESCRIPTION
[0015] The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show illustrations in accordance with example embodiments. These example embodiments, which may be herein also referred to as “examples” are described in enough detail to enable those skilled in the art to practice the present subject matter. However, it may be apparent to one with ordinary skill in the art, that the present invention may be practised without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to unnecessarily obscure aspects of the embodiments. The embodiments can be combined, other embodiments can be utilized, or structural, logical, and design changes can be made without departing from the scope of the claims. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope is defined by the appended claims and their equivalents.
[0016] In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one. In this document, the term “or” is used to refer to a nonexclusive “or,” such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated.
OVERVIEW
[0017] Disclosed is a backlash prevention system for achieving an anti-backlash movement of a structure. The structure may be a printhead of an additive manufacturing machine.
[0018] The backlash prevention system may comprise a first assembly and a second assembly. The first assembly may comprise a pair of screw rods, with an anti-backlash spring loaded nut screwed to each screw rod. A lateral frame extends between the two screw rods. The structure is connected to the lateral frame. As the screw rods are rotated to move the lateral frame, and along with it the structure, up or down, the anti-backlash spring loaded nut reduces the backlash in the movement.
[0019] The second assembly comprises a rack and pinion setup and a slider assembly. The pinion is an anti-backlash gear. One of track or slider of the slider assembly is connected to the structure and the other is connected to a housing, wherein the housing encompasses the structure. Rotation of the pinion moves the structure up and down and the slider assembly enables the structure to slide along an axis. The anti-backlash gear reduces the backlash during the movement of the structure.
BACKLASH PREVENTION SYSTEM
[0020] A backlash prevention system 100 is discussed as applied to an additive manufacturing machine, although those skilled in this art will understand that the principles disclosed are in no way limiting the backlash prevention system 100 to the additive manufacturing machine and that the backlash prevention system 100 is equally applicable to machines where there is a need to eliminate comparable backlash.
[0021] Referring to FIG. 1, an isometric view of a backlash prevention system 100 is shown, in accordance with an embodiment. The backlash prevention system 100 may be configured to achieve an anti-backlash movement of a structure 102. The structure 102 for illustration purposes is a printhead 102 of an additive manufacturing machine. In an embodiment, the structure 102 may be any component that is configured to be moved along an axis. The backlash prevention system 100 may comprise a first assembly 104 and a second assembly 108.
[0022] FIG. 2 is an isometric view of the backlash prevention system 100 depicting the first assembly 104, in accordance with an embodiment. The first assembly 104 may comprise a screw rod 202 and an anti-backlash spring loaded nut 204. The anti-backlash spring loaded nut 204 may be screwed to the screw rod 202.
[0023] In an embodiment, the additive manufacturing machine may comprise a pair of screw rods 202. A lateral frame 110 may extend between the two screw rods 202, wherein the printhead 102 may be connected to the lateral frame 110. As the pair of screw rods 202 are rotated, the lateral frame 110, and along with it the printhead 102, may move up or down along a first axis 106, depending on the direction of rotation of the screw rod 202. The anti-backlash spring loaded nut 204 that may be screwed to each of the screw rods 202 reduces the backlash in the screw rods 202 during the movement of the lateral frame 110 along the first axis 106. The first axis 106, as applied to an additive manufacturing machine may be an axis that is perpendicular to face of a print plate.
[0024] In an embodiment, the anti-backlash spring loaded nut 204 may be in contact with the lateral frame 110 such that the rotation of the anti-backlash spring loaded nut 204 moves the lateral frame 110, and along with it the printhead 102, up and down along the first axis 106.
[0025] In an embodiment, the first assembly 104 may further comprise a pair of sliding members 206. The sliding members 206 may enable the structure 102 to slide along the first axis 106. Each sliding member 206 may comprise a slider guide 208 and a sliding block 210. Each of the sliding members 206 may be arranged towards the end of the lateral frame 110 such that the sliding block 210 may be connected to end of the lateral frame 110 using screws or any other fasteners. The slider guide 208 may be connected to base (not shown) of the additive manufacturing machine. The sliding members 206 allows the lateral frame 110, and along with it the structure 102, to slide along the first axis 106 when the screw rod 202 rotates to move the printhead 102 along the first axis 106.
[0026] In an embodiment, the screw rod 202 enables maximum movement of the printhead 102 by a first distance. The movement of the printhead 102 along the length of the screw rod 202 may be referred to as first distance.
[0027] Referring to FIGs. 3A, 3B and 3C, the second assembly 108 is described in accordance with an embodiment. The second assembly 108 comprises a rack and pinion setup 302 and a slider assembly 306.
[0028] In an embodiment, a housing 112 may be connected to the lateral frame 110, wherein the housing 112 encompasses the printhead 102. The housing 112 provides maximum movement of the printhead 102 by a second distance. As an example, in an additive manufacturing machine comprising two printheads 102, when one of the two printheads 102 are to be extended and the other retracted, the printhead 102 is moved along the first axis 106 by a second distance.
[0029] In an embodiment, the first distance is greater than the second distance.
[0030] In an embodiment, the rack and pinion setup 302 may be connected to the printhead 102 such that the rotation of the pinion 304 results in movement of the printhead 102 along the first axis 106. A motor 314 may be configured to rotate the pinion 304 in clockwise or anti-clockwise direction depending upon the direction of movement of printhead 102 that may be desired. The motor 314 may be connected to inner surface 316 of the housing 112 using fasteners 320 that are commonly used to connect two or more components.
[0031] In an embodiment, the pinion 304 is an anti-backlash gear. The anti-backlash gear provides the printhead 102 with a movement along the first axis 106 that has reduced backlash.
[0032] In an embodiment, the slider assembly 306 comprises a track 308 and a slider 310. The slider 310 may be connected to the printhead 102 using screws 318 or any other fasteners. The track 308 may be connected to the inner surface 316 of the housing 112 using screws 318. The slider assembly 306 allows the printhead to slide along the first axis 106 when the pinion 304 rotates to move the printhead 102 along the first axis 106. Further, the slider assembly 306 provides support to the printhead 102 and slidably connects the printhead 102 to the housing 112.
[0033] In another embodiment, the track 308 may be connected to the printhead 102 and the slider 310 may be connected to the inner surface 316 of the housing 112.
[0034] In an embodiment, a structure holder 312 may be provided to support the printhead 102 (or the structure 102). The rack and pinion setup 302 may be attached to the structure holder 312 to move the printhead 102 along the first axis 106. One of the track 308 or the slider 310 of the slider assembly 306 may be connected to the structure holder 312 and the other (slider 310 or the track 308) may be connected to the housing 112.
[0035] FIGs. 4A and 4B illustrate the working of the first assembly 104, in accordance with an embodiment. To move the printhead 102 from a lower position 402 to an upper position 404, the screw rod 202 is rotated so that the lateral frame 110 moves up along the first axis 106. As the screw rod 202 is rotated, the anti-backlash spring loaded nut 204 screwed to the screw rod 202 reduces the backlash during the movement of the lateral frame 110. The operation of the first assembly 104 to move the printhead 102 up along the first axis 106 results in movement of the second assembly 108 along the first axis 106.
[0036] FIGs. 5A and 5B illustrate the working of the second assembly 108, in accordance with an embodiment. In the instant embodiment, the additive manufacturing machine uses two printheads, first printhead 502 and second printhead 504 each printhead using a different raw material than the other. When the raw material present in the first printhead 502 is to be used for printing purposes, the first printhead 502 is extended along the first axis 106 using the second assembly 108. The rack and pinion setup 302 used to move the first printhead 502 along the first axis 106 reduces backlash in the movement.
[0037] When the raw material present in the second printhead 504 is to be used for printing purposes, the first printhead 502 is retracted along the first axis 106 using the second assembly 108 and the second printhead 504 is extended along the first axis 106.
[0038] It shall be noted that the processes described above are described as sequence of steps; this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, or some steps may be performed simultaneously.
[0039] Although embodiments have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the system and method described herein. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.
[0040] Many alterations and modifications of the present invention will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. It is to be understood that the description above contains many specifications; these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the personally preferred embodiments of this invention. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents rather than by the examples given.
Listing of reference numerals
[0041] 100 – backlash prevention system; 102 – structure; 104 – first assembly; 106 – first axis; 108 – second assembly; 110 – lateral frame; 112 – housing; 202 – screw rod; 204 – anti-backlash spring loaded nut; 302 – rack and pinion setup; 304 – pinion; 306 – slider assembly; 308 – track; 310 – slider; 312 – structure holder; 314 – motor; 316 – inner surface of the housing 112; 318 – screw; 320 – fastener; 402 – lower position; 404 – upper position; 502 – first printhead; and 504 – second printhead.