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Title:
A MOTION TRANSFORMING MECHANISM
Document Type and Number:
WIPO Patent Application WO/1999/020919
Kind Code:
A1
Abstract:
A motion transforming mechanism (10) includes a plurality of serially connected links (12, 18, 26), adjacent links being connected in end-to-end relationship to form a chain. A first mounting formation (14) is defined proximate a first, free end of a first link (12) in the chain for mounting the first ink (12) to a drive means which, in use, imparts arcuate, oscillatory motion to said first link (12). A second mounting formation (32) is defined proximate a free end of a last link (26) in the chain for mounting said free end to an anchor so that, in use, the last link (26) is displaceable arcuately about its opposed end, the links (12, 18, 26) being arranged to transform arcuate, oscillatory motion at said free end of the first link (12) into cam motion to an element which, in use, is arranged at a region intermediate the free end of the first link (12) and the free end of the last link (26).

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Inventors:
BAJIC MILAN (ZA)
Application Number:
PCT/US1998/022351
Publication Date:
April 29, 1999
Filing Date:
October 22, 1998
Export Citation:
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Assignee:
METAL BOX CO SOUTH AFRICA (ZA)
HANDELMAN JOSEPH H (US)
BAJIC MILAN (ZA)
International Classes:
F16H21/44; (IPC1-7): F16H21/44
Foreign References:
US4848175A1989-07-18
US4023423A1977-05-17
US1135655A1915-04-13
US3488955A1970-01-13
Attorney, Agent or Firm:
Handelman, Joseph H. (26 West 61st Street New York, NY, US)
Download PDF:
Claims:
CLAIMS
1. A motion transforming mechanism which includes a plurality of serially connected links, adjacent links being connected in endtoend relationship to form a chain; a first mounting formation proximate a first, free end of a first link in the chain for mounting the first link to a drive means which, in use, imparts arcuate, oscillatory motion to said first link; and a second mounting formation proximate a free end of a last link in the chain for mounting said free end to an anchor so that, in use, the last link is displaceable arcuately about its opposed end, the links being arranged to transform arcuate, oscillatory motion at said free end of the first link into cam motion to an element which, in use, is arranged at a region intermediate the free end of the first link and the free end of the last link.
2. The mechanism as claimed in Claim 1 which includes three links, being the first link, the last link and an intermediate, second link, the first link and the second link each being of an effective length, L, and the last, third link being of an effective length, 0.5L.
3. The mechanism as claimed in Claim 2 in which a first end of the second link is pivotally connected to an opposed end of the first link and an opposed end of the second link is pivotally connected to a first end of the third link, an opposed end of the third link being the free end of the third link.
4. The mechanism as claimed in Claim 3 in which the effective length, L, of the first link is measured from its mounting formation to its pivotal connection to the second link, the effective length, L, of the second link is measured between its pivotal connections to the first link and the third link and the effective length, 0.5L, of the third link is measured between its pivotal connection to the second link and the mounting formation of the third link.
5. The mechanism as claimed in Claim 4 in which the first mounting formation proximate the first end of the first link is in the form of a bore extending through the link, a passage being defined proximate the opposed end of the first link with a complementary, first passage being defined proximate the first end of the second link, the passage of the first link and the first passage of the second link being in alignment with each other with a pivotaxis defining means being received through said passages.
6. The mechanism as claimed in Claim 5 in which the effective length, L, of the first link is measured as a distance between a centre line of the bore and a centre line of the passage proximate the opposed end of the first link.
7. The mechanism as claimed in Claim 5 or Claim 6 in which a second passage is defined proximate the opposed end of the second link with a complementary passage being defined proximate the first end of the third link, the second passage of the second link and the passage of the third link being in alignment with each other with a pivotaxis defining means being received through said passages.
8. The mechanism as claimed in Claim 7 in which the effective length, L, of the second link is measured as a distance between a centre line of its first passage and a centre line of its second passage.
9. The mechanism as claimed in Claim 7 or Claim 8 in which the mounting formation proximate the free end of the third link is in the form of a bore extending through the link, the effective length, 0.5L, of the third link being measured as a distance between a centre line of the passage of the third link and a centre line of the bore.
10. The mechanism as claimed in Claim 9 in which the links are mounted in use so that the centre line of the bore of the first link is maintained a fixed distance, D, from the centre line of the bore of the third link.
11. The mechanism as claimed in Claim 10 in which the distance D is 1.25L, where L is the effective length of each of the first link and the second link.
Description:
A MOTION TRANSFORMING MECHANISM THIS INVENTION relates to a motion transforming mechanism.

More particularly, the invention relates to a motion transforming mechanism for transforming arcuate, oscillatory motion into cam motion.

According to the invention, there is provided a motion transforming mechanism which includes a plurality of serially connected links, adjacent links being connected in end-to-end relationship to form a chain; a first mounting formation proximate a first, free end of a first link in the chain for mounting the first link to a drive means which, in use, imparts arcuate, oscillatory motion to said first link; and a second mounting formation proximate a free end of a last link in the chain for mounting said free end to an anchor so that, in use, the last link is displaceable arcuately about its opposed end, the links being arranged to transform arcuate, oscillatory motion at said free end of the first link into cam motion to an element which, in use, is arranged at a region intermediate the free end of the first link and the free end of the last link.

The mechanism may include three links, being the first link, the last link and an intermediate, second link, the first link and the second link

each being of an effective length, L, and the last, third link being of an effective length, 0.5L.

A first end of the second link may be pivotally connected to an opposed end of the first link and an opposed end of the second link may be pivotally connected to a first end of the third link, an opposed end of the third link being the free end of the third link.

Then, the effective length, L, of the first link may be measured from its mounting formation to its pivotal connection to the second link, the effective length, L, of the second link may be measured between its pivotal connections to the first link and the third link and the effective length, 0.5L, of the third link may be measured between its pivotal connection to the second link and the mounting formation of the third link.

The first mounting formation proximate the first end of the first link may be in the form of a bore extending through the link, a passage being defined proximate the opposed end of the first link with a complementary, first passage being defined proximate the first end of the second link, the passage of the first link and the first passage of the second link being in alignment with each other with a pivot-axis defining means being received through said passages. Then, the effective length, L, of the first link may be measured as a distance between a centre line of the bore

and a centre line of the passage proximate. the opposed end of the first link.

A second passage may be defined proximate the opposed end of the second link with a complementary passage being defined proximate the first end of the third link, the second passage of the second link and the passage of the third link being in alignment with each other with a pivot-axis defining means being received through said passages. Then, the effective length, L, of the second link may be measured as a distance between a centre line of its first passage and a centre line of its second passage.

The mounting formation proximate the free end of the third link may be in the form of a bore extending through the link, the effective length, 0.5L, of the third link being measured as a distance between a centre line of the passage of the third link and a centre line of the bore.

The mechanism may include a drive means to which the first end of the first link is connected, via the first mounting formation, and an anchor to which the opposed end of the third link is connected, via the second mounting formation. The drive means may, for example, be in the form of a drive shaft which is received in the bore of the first link and which provides arcuate, oscillatory motion to the first link. Then, the anchor may be in the form of a cam shaft which is rotatably mounted on a support structure with the cam shaft being received in the bore of the third link. By

having the drive shaft and the cam shaft mounted a predetermined distance apart and extending parallel to each other, cam motion is imparted to the assembly of links at a junction between the second link and the third link or along the third link. Then, the element may be mounted, in use, at this junction, or on the third link, which element moves in a cam-like manner, in use. By appropriate choice of element, the desired cam motion can be achieved.

To effect the cam-like motion, the links may then be mounted in use so that the centre line of the bore of the first link is maintained a fixed distance, D, from the centre line of the bore of the third link. The distance D may be 1.25L, where L is the effective length of each of the first link and the second link.

The invention is now described by way of example with reference to the accompanying diagrammatic drawings.

In the drawings, Figure 1 shows a schematic side view of a motion transforming mechanism, in accordance with the invention; and Figure 2 shows a three dimensional view of the motion transforming mechanism.

In the drawings, reference numeral 10 generally designates a motion transforming mechanism in accordance with the invention.

The motion transforming mechanism 10 comprises a first link 12 of effective length, L. The link 12 has a mounting formation in the form of a bore 14 defined at a first end 12.1 of the link 12. A passage 16 is defined at an opposed end 12.2 of the link 12.

A second link 18 has a first end 18.1 pivotally connected to the end 12.2 of the first link 12. A further passage 20 is defined at the end 18.1 of the link 18. A pivot pin 22 is received through the aligned passages 16,20 of the links 12,18 respectively, for effecting pivotal connection of the link 18 relative to the link 12. The link 18, which is also of effective length, L, has a passage 24 defined at an opposed end 18.2.

A third link 26, of effective length, 0.5L, is pivotally connected, via its first end 26.1, to the end 18.2 of the link 18. Thus, a passage 28 is defined through the first end 26.1 of the link 26, the passage 28 being aligned with the passage 24 at the end 18.2 of the link 18. A pivot pin 30 is received in the aligned passages 24,28 to effect pivotal connection of the link 26 with respect to the link 18.

A mounting formation in the form of a bore 32 is defined at an

opposed end 26.2 of the link 26.

A drive means in the form of a drive shaft 34 is received through the bore 14 in the link 12. The effective length, L, of the link 12 is measured between a centre of rotation 34.1 (on a centre line of the bore 14) of the drive shaft 34 and a centre of rotation 22.1 (on a centre line of the passages 16,20) of the pivot pin 22. Similarly, the effective length, L, of the link 18 is measured between the centre of rotation 22.1 of the pivot pin 22 and a centre of rotation 30.1 (on a centre line of the passages 24,28) of the pivot pin 30. An anchor in the form of a cam shaft 36 is received through the bore 32 in the end 26.2 of the link 26, the cam shaft 36 extending parallel to the drive shaft 34. Once again, the effective length, 0.5L, of the link 26 is measured between the centre of rotation 30.1 of the pivot pin 30 and a centre of rotation 36.1 (on a centre line of the bore 32) of the cam shaft 36.

It will be appreciated that, in use, both the drive shaft 34 and the cam shaft 36 are arranged in a fixed orientation with respect to each other. The drive shaft 34 and the cam shaft 36 are so arranged that a distance, D, between the centre of rotation 34.1 of the drive shaft 34 and the centre of rotation 36.1 of the cam shaft 36 is 1.25L. In the orientation of the mechanism 10 illustrated in Figure 1 of the drawings, the distance, D, is measured horizontally. Then, once again, referring to the orientation

of the mechanism 10 as illustrated in Figure 1 of the drawings, a vertical distance between the centre of rotation 34.1 of the drive shaft 34 and the centre of rotation 36.1 of the cam shaft 36 is L.

In use, a cam-like motion imparting element 40 is connected to the third link 26. As illustrated, the element 40 is shown connected to the end 26.1 of the link 26 but it will be appreciated that the element 40 could be connected anywhere along the length of the link 26.

The drive shaft 34 is connected to a prime mover (not shown) which drives the drive shaft 34 in an arcuate, oscillatory manner to impart arcuate, oscillatory motion to the first link 12 as illustrated by the arrows 38. Due to the connection of the links 12,18 and 26 and the positioning of the drive shaft 34 with respect to the cam shaft 36, arcuate oscillatory motion imparted to the link 12 causes cam-like motion to be imparted to the element 40 mounted on the link 26.

By appropriate selection of the element 40, accurate dwell and throw of the element 40 can be achieved for imparting a desired linear motion to a piece of equipment connected to a free end 40.1 of the element 40, the free end 40.1 of the element 40 moving in the direction of arrows 42.

It is a particular advantage of the invention that the mechanism 10 obviates the need for designing and manufacturing complex cam profiles.

It will be appreciated that the design and manufacture of such cams is time consuming and costly. Further, the applicant believes that a more accurate cam motion can be effected than with conventional cams. In addition, the need for a drive shaft which is driven through 360° is obviated, thereby also obviating the need for cam followers, or the like. Thus, with the provision of the mechanism 10, a more compact piece of equipment results than if standard cams and followers were to be used. Further, the need for cam lubricants is obviated which is an important consideration where the equipment incorporating the mechanism 10 is utilized in applications where hygienic aspects are of importance, for example, in the packaging of foodstuffs or beverages.